Mark W. Grinstaff is the William Fairfield Warren Distinguished Professor, and a Professor of Biomedical Engineering, Chemistry, Materials Science and Engineering, and Medicine at Boston University
Electrospun non-woven poly(ε-caprolactone) (PCL) microfiber meshes are described as biodegradable... more Electrospun non-woven poly(ε-caprolactone) (PCL) microfiber meshes are described as biodegradable, mechanically robust, and reusable polymeric oil sorbents capable of selectively retrieving oil from simulated oil spills in both fresh and seawater scenarios. Hydrophobic PCL meshes have >99.5% (oil over water) oil selectivity and oil absorption capacities of ~10 grams of oil per gram of sorbent material, which is shown to be a volumetrically driven process. Both the oil selectivity and absorption capacity remained constant over several oil absorption and vacuum assisted retrieval cycles when removing crude oil or mechanical pump oil from deionized water or simulated seawater mixtures. Finally, when challenged with surfactant stabilized water-in-oil emulsions, the PCL meshes continued to show selective oil absorption. These studies add to the knowledge base of synthetic oil sorbents highlighting a need for biodegradable synthetic oil sorbents which balance porosity and mechanical integrity enabling reuse, allowing for the efficient recovery of oil after an accidental oil spill. Electronic Supplementary Information (ESI) available: Additional figures and experimental protocols. See
This work demonstrates a facile fabrication method to produce superhydrophobic coatings on chemic... more This work demonstrates a facile fabrication method to produce superhydrophobic coatings on chemically distinct materials using the electrospraying process. Coatings are mechanically robust, three-dimensional, and formed using a single fabrication step. Interest continues to evolve in superhydrophobic surfaces, where the unique property of having a permanent or semi-permanent air layer at a material surface can lead to improved material performance in specific applications. 1-15 Superhydrophobicity is achieved by trapping air at the material-water interface by adding sufficient surface roughness to a low energy material using one of a variety of microfabrication, surface modification, or surface coating techniques. 16-25 Fabricating a surface with superhydrophobicity has become a relatively straightforward procedure, but a number of complexities arise with the usage of such surfaces for practical application. 16 Producing a superhydrophobic surface that meets all of the following design criteria represents a significant challenge: 1) use of readily available hydrophobic materials which can be fabricated with sufficient surface roughness to promote superhydrophobicity; 2) selection of a one-step fabrication technique that is easily scalable for industrial use, utilizes relatively mild processing conditions, and can be coated over large areas; and 3) sufficient mechanical integrity of the surface for its intended application.
We describe an electrochemical strategy to transduce allosteric transcription factor (aTF) bindin... more We describe an electrochemical strategy to transduce allosteric transcription factor (aTF) binding affinity to sense steroid hormones. Our approach utilizes square wave voltammetry (SWV) to monitor changes in current output as a progesterone (PRG) specific aTF (SRTF1) unbinds from the cognate DNA sequence in the presence of PRG. The sensor detects PRG in artificial urine samples with sufficient sensitivity suitable for clinical applications. Our results highlight the capability of using aTFs as the biorecognition elements to develop electrochemical point-of-care biosensors for detection of small molecule biomarkers and analytes.
*This paper highlights and contextualizes research findings presented at an IUPAC-sponsored works... more *This paper highlights and contextualizes research findings presented at an IUPAC-sponsored workshop entitled DNA Supramolecular Assemblies, held in Avignon, France on 5-6 May 2004. Special topic coverage in Pure and Applied Chemistry aims to highlight topical themes and offer critical insight into new and emerging concepts in chemical sciences.
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. High lev... more Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. High levels of free fatty acids in the liver impair hepatic lysosomal acidification and reduce autophagic flux. We investigate whether restoration of lysosomal function in NAFLD recovers autophagic flux, mitochondrial function, and insulin sensitivity. Here, we report the synthesis of novel biodegradable acid-activated acidifying nanoparticles (acNPs) as a lysosome targeting treatment to restore lysosomal acidity and autophagy. The acNPs, composed of fluorinated polyesters, remain inactive at plasma pH, and only become activated in lysosomes after endocytosis. Specifically, they degrade at pH of ~6 characteristic of dysfunctional lysosomes, to further acidify and enhance the function of lysosomes. In established in vivo high fat diet mouse models of NAFLD, re-acidification of lysosomes via acNP treatment restores autophagy and mitochondria function to lean, healthy levels. This restoration, conc...
Solid stress, one of the physical hallmarks of cancer, affects trafficking and infiltration of im... more Solid stress, one of the physical hallmarks of cancer, affects trafficking and infiltration of immune cells, promotes metastasis and tumorigenic pathways, and impedes therapeutic delivery. Despite these clinical ramifications, questions remain regarding the origins and consequences of solid stresses and the differential response of tumor versus normal cells to solid stresses. Answering these fundamental questions requires probing solid stresses at the cellular scale, where biological and immunological responses manifest, as well as in vivo, where the complexities of the tumor microenvironment are present. Here, we report the first in vivo and multi-scale measurements of solid stress in mouse models of breast cancer using multi-modal intravital microscopy of deformable hydrogels complemented with mathematical modeling. Utilizing the capabilities of these methods, such as the high-resolution, longitudinal, and 3-D measurements of local solid stress, we measure and compare solid stress...
Cationic computed tomography contrast agents are more sensitive for detecting cartilage degenerat... more Cationic computed tomography contrast agents are more sensitive for detecting cartilage degeneration than anionic or non‐ionic agents. However, osteoarthritis‐related loss of proteoglycans and increase in water content contrarily affect the diffusion of cationic contrast agents, limiting their sensitivity. The quantitative dual‐energy computed tomography technique allows the simultaneous determination of the partitions of iodine‐based cationic (CA4+) and gadolinium‐based non‐ionic (gadoteridol) agents in cartilage at diffusion equilibrium. Normalizing the cationic agent partition at diffusion equilibrium with that of the non‐ionic agent improves diagnostic sensitivity. We hypothesize that this sensitivity improvement is also prominent during early diffusion time points and that the technique is applicable during contrast agent diffusion. To investigate the validity of this hypothesis, osteochondral plugs (d = 8 mm, N = 33), extracted from human cadaver (n = 4) knee joints, were imme...
Myeloid-derived suppressor cells (MDSCs) are immune suppressive cells that massively accumulate u... more Myeloid-derived suppressor cells (MDSCs) are immune suppressive cells that massively accumulate under pathological conditions to suppress T cell immune response. Dysregulated cell death contributes to MDSC accumulation, but the molecular mechanism underlying this cell death dysregulation is not fully understood. In this study, we report that neutral ceramidase (N-acylsphingosine amidohydrolase [ASAH2]) is highly expressed in tumor-infiltrating MDSCs in colon carcinoma and acts as an MDSC survival factor. To target ASAH2, we performed molecular docking based on human ASAH2 protein structure. Enzymatic inhibition analysis of identified hits determined NC06 as an ASAH2 inhibitor. Chemical and nuclear magnetic resonance analysis determined NC06 as 7-chloro-2-(3-chloroanilino)pyrano[3,4-e][1,3]oxazine-4,5-dione. NC06 inhibits ceramidase activity with an IC50 of 10.16–25.91 μM for human ASAH2 and 18.6–30.2 μM for mouse Asah2 proteins. NC06 induces MDSC death in a dose-dependent manner, an...
Bioengineering of the human auricle remains a significant challenge, where the complex and unique... more Bioengineering of the human auricle remains a significant challenge, where the complex and unique shape, the generation of high-quality neocartilage, and shape preservation are key factors. Future regenerative medicine-based approaches for auricular cartilage reconstruction will benefit from a smart combination of various strategies. Our approach to fabrication of an ear-shaped construct uses hybrid bioprinting techniques, a recently identified progenitor cell population, previously validated biomaterials, and a smart scaffold design. Specifically, we generated a 3D-printed polycaprolactone (PCL) scaffold via fused deposition modeling, photocrosslinked a human auricular cartilage progenitor cell-laden gelatin methacryloyl (gelMA) hydrogel within the scaffold, and cultured the bioengineered structure in vitro in chondrogenic media for 30 days. Our results show that the fabrication process maintains the viability and chondrogenic phenotype of the cells, that the compressive properties of the combined PCL and gelMA hybrid auricular constructs are similar to native auricular cartilage, and that biofabricated hybrid auricular structures exhibit excellent shape fidelity compared with the 3D digital model along with deposition of cartilage-like matrix in both peripheral and central areas of the auricular structure. Our strategy affords an anatomically enhanced auricular structure with appropriate mechanical properties, ensures adequate preservation of the auricular shape during a dynamic in vitro culture period, and enables chondrogenically potent progenitor cells to produce abundant cartilage-like matrix throughout the auricular construct. The combination of smart scaffold design with 3D bioprinting and cartilage progenitor cells holds promise for the development of clinically translatable regenerative medicine strategies for auricular reconstruction.
Immobilization of biosensors on surfaces is a key step toward development of devices for real‐wor... more Immobilization of biosensors on surfaces is a key step toward development of devices for real‐world applications. Here the preparation, characterization, and evaluation of a surface‐bound transcription factor–nucleic acid complex for analyte detection as an alternative to conventional systems employing aptamers or antibodies are described. The sensor consists of a gold surface modified with thiolated Cy5 fluorophore‐labeled DNA and an allosteric transcription factor (TetR) linked to a quantum dot (QD). Upon addition of anhydrotetracycline (aTc)—the analyte—the TetR‐QDs release from the surface‐bound DNA, resulting in loss of the Förster resonance energy transfer signal. The sensor responds in a dose‐dependent manner over the relevant range of 0–200 µm aTc with a limit of detection of 80 nm. The fabrication of the sensor and the subsequent real‐time quantitative measurements establish a framework for the design of future surface‐bound, affinity‐based biosensors using allosteric trans...
Reported here is the first aqueous ring‐opening polymerization (ROP) of N‐carboxyanhydrides (NCAs... more Reported here is the first aqueous ring‐opening polymerization (ROP) of N‐carboxyanhydrides (NCAs) using α‐amino‐poly(ethylene oxide) as a macroinitiator to protect the NCA monomers from hydrolysis through spontaneous in situ self‐assembly (ISA). This ROPISA process affords well‐defined amphiphilic diblock copolymers that simultaneously form original needle‐like nanoparticles.
Early degenerative changes of articular cartilage are detected using contrast-enhanced computed t... more Early degenerative changes of articular cartilage are detected using contrast-enhanced computed tomography (CT) with a cationic contrast agent (CA). However, cationic CA diffusion into degenerated cartilage decreases with proteoglycan depletion and increases with elevated water content, thus hampering tissue evaluation at early diffusion time points. Furthermore, the contrast at synovial fluid-cartilage interface diminishes as a function of diffusion time hindering accurate cartilage segmentation. For the first time, we employ quantitative dual-energy CT (QDECT) imaging utilizing a mixture of three CAs (cationic CA4+ and non-ionic gadoteridol which are sensitive to proteoglycan and water contents, respectively, and bismuth nanoparticles which highlight the cartilage surface) to simultaneously segment the articulating surfaces and determine of the cartilage condition. Intact healthy, proteoglycan-depleted, and mechanically injured bovine cartilage samples (n = 27) were halved and ima...
An accessible method to produce a click chemistry-ready, zwitterionic polymer from commercially a... more An accessible method to produce a click chemistry-ready, zwitterionic polymer from commercially available reagents facilitates efficient DNA grafting to quantum dots.
Six fungal metabolites, of which five were new, including one (1) with a dioxa[4.3.3]propellane r... more Six fungal metabolites, of which five were new, including one (1) with a dioxa[4.3.3]propellane ring system, were discovered, identified, and structurally elucidated from Neosetophoma sp. (strain MSX50044); these compounds are similar to the bis-tropolone, eupenifeldin. Three of the meroterpenoids are potent cytotoxic agents against breast, ovarian, mesothelioma, and lung cancer cells with nanomolar IC 50 values while not inducing mitochondrial toxicity at 12.5 μM.
Despite the presence of CTLs in the tumor microenvironment, the majority of immunogenic human col... more Despite the presence of CTLs in the tumor microenvironment, the majority of immunogenic human colon cancer does not respond to immune checkpoint inhibitor immunotherapy, and microsatellite instable (MSI) tumors are not naturally eliminated. The molecular mechanism underlying the inactivity of tumor-infiltrating CTLs is unknown. We report here that CTLs were present in both MSI and microsatellite stable colon tumors. The expression of the H3K9me3-specific histone methyltransferase SUV39H1 was significantly elevated in human colon carcinoma compared with normal colon tissues. Using a mouse colon carcinoma model, we further determined that tumor-infiltrating CTLs in the colon tumor microenvironment have high expression of SUV39H1. To target SUV39H1 in the tumor microenvironment, a virtual chemical library was screened on the basis of the SET (suppressor of variegation 3–9, enhancer of zeste and trithorax) domain structure of the human SUV39H1 protein. Functional enzymatic activity assa...
Oligonucleotide-based agents have the potential to treat or cure almost any disease, and are one ... more Oligonucleotide-based agents have the potential to treat or cure almost any disease, and are one of the key therapeutic drug classes of the future. Bioconjugated oligonucleotides, a subset of this class, are emerging from basic research and being successfully translated to the clinic. In this review, we first briefly describe two approaches for inhibiting specific genes using oligonucleotides-antisense DNA (ASO) and RNA interference (RNAi)followed by a discussion on delivery to cells. We then summarize and analyze recent developments in bioconjugated oligonucleotides including those possessing GalNAc, cell penetrating peptides, αtocopherol, aptamers, antibodies, cholesterol, squalene, fatty acids, or nucleolipids. These novel conjugates provide a means to enhance tissue targeting, cell internalization, endosomal escape, target binding specificity, resistance to nucleases, and more. We next describe those bioconjugated oligonucleotides approved for patient use or in clinical trials. Finally, we summarize the state of the field, describe current limitations, and discuss future prospects. Bioconjugation chemistry is at the centerpiece of this therapeutic oligonucleotide revolution, and significant opportunities exist for development of new modification chemistries, for mechanistic studies at the chemical-biology interface, and for translating such agents to the clinic.
Solid-state nanopores are an emerging biosensor for nucleic acid and protein characterization. Fo... more Solid-state nanopores are an emerging biosensor for nucleic acid and protein characterization. For use in a clinical setting, solid-state nanopore sensing requires sample preparation and purification, fluid handling, a heating element, electrical noise insulators, and an electrical readout detector, all of which hamper its translation to a point-of-care diagnostic device. A standalone microfluidic-based nanopore device is described that combines a bioassay reaction/purification chamber with a solid-state nanopore sensor. The microfluidic device is composed of the high-temperature/solvent resistance Zeonex plastic, formed via micromachining and heat bonding, enabling the use of both a heat regulator and a magnetic controller. Fluid control through the microfluidic channels and chambers is controlled via fluid port selector valves and allows up to eight different solutions. Electrical noise measurements and DNA translocation experiments demonstrate the integrity of the device, with performance comparable to a conventional stand-alone nanopore setup. However, the microfluidic-nanopore setup is superior in terms of ease of use. To showcase the utility of the device, single molecule detection of a DNA polymerase chain reaction product, after magnetic bead DNA separation, is accomplished on-chip.
The translation of biomaterial based and regenerative therapies from the laboratory to patients i... more The translation of biomaterial based and regenerative therapies from the laboratory to patients involves multiple challenges. One of the most pressing challenges is the educational one: to train a cohort of scientists and engineers capable of translating their discoveries from bench to market to clinic. To meet this need, translational training programs are being implemented globally at universities and as partnerships between universities and corporations. In this perspective, we describe two translational NIH T32 graduate and postgraduate training programs that augment the traditional approach to training early stage scientists and engineers. At the graduate level, Boston University developed and implemented the Translational Research in Biomaterials (TRB) predoctoral training program. At the postgraduate level, Rutgers, The State University of New Jersey, developed and implemented the Translational Research in Regenerative Medicine (TRRM) program for postdoctoral training. These programs are motivated by the need for training in translational research in the biomedical field, by young scientists' requests for such training, and by the fundamental challenges facing future discovery and clinical implementation of biomaterialbased technologies. The TRB program immerses trainees in the concept of translating an idea from the research laboratory to the clinic, introduces them to the challenges of such an endeavor, provides discussions with relevant faculty (for example, with businesses, patient care, or clinical trial experience), and educates them in the critical areas required for their future careers. Similarly, the TRRM program emphasizes translational research and the concept of "training without borders," which enables collaborations across several geographically dispersed institutions so as to make regional experts accessible regardless of where they are located physically. Both programs promote interdisciplinary research, expose young scientists and engineers to challenges outside of their specialty, and build interpersonal skills for cross-disciplinary communication. The TRB program focuses on quantitative science and engineering courses, together with translation-based courses in clinical trials and business. The TRRM program focuses on broadening the horizon of its trainees through exposure to a wider network of mentors than traditional postdoctoral *
A guidebook and reference for detecting and characterizing proteins at the single-molecule level ... more A guidebook and reference for detecting and characterizing proteins at the single-molecule level using nanopores.
Electrospun non-woven poly(ε-caprolactone) (PCL) microfiber meshes are described as biodegradable... more Electrospun non-woven poly(ε-caprolactone) (PCL) microfiber meshes are described as biodegradable, mechanically robust, and reusable polymeric oil sorbents capable of selectively retrieving oil from simulated oil spills in both fresh and seawater scenarios. Hydrophobic PCL meshes have >99.5% (oil over water) oil selectivity and oil absorption capacities of ~10 grams of oil per gram of sorbent material, which is shown to be a volumetrically driven process. Both the oil selectivity and absorption capacity remained constant over several oil absorption and vacuum assisted retrieval cycles when removing crude oil or mechanical pump oil from deionized water or simulated seawater mixtures. Finally, when challenged with surfactant stabilized water-in-oil emulsions, the PCL meshes continued to show selective oil absorption. These studies add to the knowledge base of synthetic oil sorbents highlighting a need for biodegradable synthetic oil sorbents which balance porosity and mechanical integrity enabling reuse, allowing for the efficient recovery of oil after an accidental oil spill. Electronic Supplementary Information (ESI) available: Additional figures and experimental protocols. See
This work demonstrates a facile fabrication method to produce superhydrophobic coatings on chemic... more This work demonstrates a facile fabrication method to produce superhydrophobic coatings on chemically distinct materials using the electrospraying process. Coatings are mechanically robust, three-dimensional, and formed using a single fabrication step. Interest continues to evolve in superhydrophobic surfaces, where the unique property of having a permanent or semi-permanent air layer at a material surface can lead to improved material performance in specific applications. 1-15 Superhydrophobicity is achieved by trapping air at the material-water interface by adding sufficient surface roughness to a low energy material using one of a variety of microfabrication, surface modification, or surface coating techniques. 16-25 Fabricating a surface with superhydrophobicity has become a relatively straightforward procedure, but a number of complexities arise with the usage of such surfaces for practical application. 16 Producing a superhydrophobic surface that meets all of the following design criteria represents a significant challenge: 1) use of readily available hydrophobic materials which can be fabricated with sufficient surface roughness to promote superhydrophobicity; 2) selection of a one-step fabrication technique that is easily scalable for industrial use, utilizes relatively mild processing conditions, and can be coated over large areas; and 3) sufficient mechanical integrity of the surface for its intended application.
We describe an electrochemical strategy to transduce allosteric transcription factor (aTF) bindin... more We describe an electrochemical strategy to transduce allosteric transcription factor (aTF) binding affinity to sense steroid hormones. Our approach utilizes square wave voltammetry (SWV) to monitor changes in current output as a progesterone (PRG) specific aTF (SRTF1) unbinds from the cognate DNA sequence in the presence of PRG. The sensor detects PRG in artificial urine samples with sufficient sensitivity suitable for clinical applications. Our results highlight the capability of using aTFs as the biorecognition elements to develop electrochemical point-of-care biosensors for detection of small molecule biomarkers and analytes.
*This paper highlights and contextualizes research findings presented at an IUPAC-sponsored works... more *This paper highlights and contextualizes research findings presented at an IUPAC-sponsored workshop entitled DNA Supramolecular Assemblies, held in Avignon, France on 5-6 May 2004. Special topic coverage in Pure and Applied Chemistry aims to highlight topical themes and offer critical insight into new and emerging concepts in chemical sciences.
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. High lev... more Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. High levels of free fatty acids in the liver impair hepatic lysosomal acidification and reduce autophagic flux. We investigate whether restoration of lysosomal function in NAFLD recovers autophagic flux, mitochondrial function, and insulin sensitivity. Here, we report the synthesis of novel biodegradable acid-activated acidifying nanoparticles (acNPs) as a lysosome targeting treatment to restore lysosomal acidity and autophagy. The acNPs, composed of fluorinated polyesters, remain inactive at plasma pH, and only become activated in lysosomes after endocytosis. Specifically, they degrade at pH of ~6 characteristic of dysfunctional lysosomes, to further acidify and enhance the function of lysosomes. In established in vivo high fat diet mouse models of NAFLD, re-acidification of lysosomes via acNP treatment restores autophagy and mitochondria function to lean, healthy levels. This restoration, conc...
Solid stress, one of the physical hallmarks of cancer, affects trafficking and infiltration of im... more Solid stress, one of the physical hallmarks of cancer, affects trafficking and infiltration of immune cells, promotes metastasis and tumorigenic pathways, and impedes therapeutic delivery. Despite these clinical ramifications, questions remain regarding the origins and consequences of solid stresses and the differential response of tumor versus normal cells to solid stresses. Answering these fundamental questions requires probing solid stresses at the cellular scale, where biological and immunological responses manifest, as well as in vivo, where the complexities of the tumor microenvironment are present. Here, we report the first in vivo and multi-scale measurements of solid stress in mouse models of breast cancer using multi-modal intravital microscopy of deformable hydrogels complemented with mathematical modeling. Utilizing the capabilities of these methods, such as the high-resolution, longitudinal, and 3-D measurements of local solid stress, we measure and compare solid stress...
Cationic computed tomography contrast agents are more sensitive for detecting cartilage degenerat... more Cationic computed tomography contrast agents are more sensitive for detecting cartilage degeneration than anionic or non‐ionic agents. However, osteoarthritis‐related loss of proteoglycans and increase in water content contrarily affect the diffusion of cationic contrast agents, limiting their sensitivity. The quantitative dual‐energy computed tomography technique allows the simultaneous determination of the partitions of iodine‐based cationic (CA4+) and gadolinium‐based non‐ionic (gadoteridol) agents in cartilage at diffusion equilibrium. Normalizing the cationic agent partition at diffusion equilibrium with that of the non‐ionic agent improves diagnostic sensitivity. We hypothesize that this sensitivity improvement is also prominent during early diffusion time points and that the technique is applicable during contrast agent diffusion. To investigate the validity of this hypothesis, osteochondral plugs (d = 8 mm, N = 33), extracted from human cadaver (n = 4) knee joints, were imme...
Myeloid-derived suppressor cells (MDSCs) are immune suppressive cells that massively accumulate u... more Myeloid-derived suppressor cells (MDSCs) are immune suppressive cells that massively accumulate under pathological conditions to suppress T cell immune response. Dysregulated cell death contributes to MDSC accumulation, but the molecular mechanism underlying this cell death dysregulation is not fully understood. In this study, we report that neutral ceramidase (N-acylsphingosine amidohydrolase [ASAH2]) is highly expressed in tumor-infiltrating MDSCs in colon carcinoma and acts as an MDSC survival factor. To target ASAH2, we performed molecular docking based on human ASAH2 protein structure. Enzymatic inhibition analysis of identified hits determined NC06 as an ASAH2 inhibitor. Chemical and nuclear magnetic resonance analysis determined NC06 as 7-chloro-2-(3-chloroanilino)pyrano[3,4-e][1,3]oxazine-4,5-dione. NC06 inhibits ceramidase activity with an IC50 of 10.16–25.91 μM for human ASAH2 and 18.6–30.2 μM for mouse Asah2 proteins. NC06 induces MDSC death in a dose-dependent manner, an...
Bioengineering of the human auricle remains a significant challenge, where the complex and unique... more Bioengineering of the human auricle remains a significant challenge, where the complex and unique shape, the generation of high-quality neocartilage, and shape preservation are key factors. Future regenerative medicine-based approaches for auricular cartilage reconstruction will benefit from a smart combination of various strategies. Our approach to fabrication of an ear-shaped construct uses hybrid bioprinting techniques, a recently identified progenitor cell population, previously validated biomaterials, and a smart scaffold design. Specifically, we generated a 3D-printed polycaprolactone (PCL) scaffold via fused deposition modeling, photocrosslinked a human auricular cartilage progenitor cell-laden gelatin methacryloyl (gelMA) hydrogel within the scaffold, and cultured the bioengineered structure in vitro in chondrogenic media for 30 days. Our results show that the fabrication process maintains the viability and chondrogenic phenotype of the cells, that the compressive properties of the combined PCL and gelMA hybrid auricular constructs are similar to native auricular cartilage, and that biofabricated hybrid auricular structures exhibit excellent shape fidelity compared with the 3D digital model along with deposition of cartilage-like matrix in both peripheral and central areas of the auricular structure. Our strategy affords an anatomically enhanced auricular structure with appropriate mechanical properties, ensures adequate preservation of the auricular shape during a dynamic in vitro culture period, and enables chondrogenically potent progenitor cells to produce abundant cartilage-like matrix throughout the auricular construct. The combination of smart scaffold design with 3D bioprinting and cartilage progenitor cells holds promise for the development of clinically translatable regenerative medicine strategies for auricular reconstruction.
Immobilization of biosensors on surfaces is a key step toward development of devices for real‐wor... more Immobilization of biosensors on surfaces is a key step toward development of devices for real‐world applications. Here the preparation, characterization, and evaluation of a surface‐bound transcription factor–nucleic acid complex for analyte detection as an alternative to conventional systems employing aptamers or antibodies are described. The sensor consists of a gold surface modified with thiolated Cy5 fluorophore‐labeled DNA and an allosteric transcription factor (TetR) linked to a quantum dot (QD). Upon addition of anhydrotetracycline (aTc)—the analyte—the TetR‐QDs release from the surface‐bound DNA, resulting in loss of the Förster resonance energy transfer signal. The sensor responds in a dose‐dependent manner over the relevant range of 0–200 µm aTc with a limit of detection of 80 nm. The fabrication of the sensor and the subsequent real‐time quantitative measurements establish a framework for the design of future surface‐bound, affinity‐based biosensors using allosteric trans...
Reported here is the first aqueous ring‐opening polymerization (ROP) of N‐carboxyanhydrides (NCAs... more Reported here is the first aqueous ring‐opening polymerization (ROP) of N‐carboxyanhydrides (NCAs) using α‐amino‐poly(ethylene oxide) as a macroinitiator to protect the NCA monomers from hydrolysis through spontaneous in situ self‐assembly (ISA). This ROPISA process affords well‐defined amphiphilic diblock copolymers that simultaneously form original needle‐like nanoparticles.
Early degenerative changes of articular cartilage are detected using contrast-enhanced computed t... more Early degenerative changes of articular cartilage are detected using contrast-enhanced computed tomography (CT) with a cationic contrast agent (CA). However, cationic CA diffusion into degenerated cartilage decreases with proteoglycan depletion and increases with elevated water content, thus hampering tissue evaluation at early diffusion time points. Furthermore, the contrast at synovial fluid-cartilage interface diminishes as a function of diffusion time hindering accurate cartilage segmentation. For the first time, we employ quantitative dual-energy CT (QDECT) imaging utilizing a mixture of three CAs (cationic CA4+ and non-ionic gadoteridol which are sensitive to proteoglycan and water contents, respectively, and bismuth nanoparticles which highlight the cartilage surface) to simultaneously segment the articulating surfaces and determine of the cartilage condition. Intact healthy, proteoglycan-depleted, and mechanically injured bovine cartilage samples (n = 27) were halved and ima...
An accessible method to produce a click chemistry-ready, zwitterionic polymer from commercially a... more An accessible method to produce a click chemistry-ready, zwitterionic polymer from commercially available reagents facilitates efficient DNA grafting to quantum dots.
Six fungal metabolites, of which five were new, including one (1) with a dioxa[4.3.3]propellane r... more Six fungal metabolites, of which five were new, including one (1) with a dioxa[4.3.3]propellane ring system, were discovered, identified, and structurally elucidated from Neosetophoma sp. (strain MSX50044); these compounds are similar to the bis-tropolone, eupenifeldin. Three of the meroterpenoids are potent cytotoxic agents against breast, ovarian, mesothelioma, and lung cancer cells with nanomolar IC 50 values while not inducing mitochondrial toxicity at 12.5 μM.
Despite the presence of CTLs in the tumor microenvironment, the majority of immunogenic human col... more Despite the presence of CTLs in the tumor microenvironment, the majority of immunogenic human colon cancer does not respond to immune checkpoint inhibitor immunotherapy, and microsatellite instable (MSI) tumors are not naturally eliminated. The molecular mechanism underlying the inactivity of tumor-infiltrating CTLs is unknown. We report here that CTLs were present in both MSI and microsatellite stable colon tumors. The expression of the H3K9me3-specific histone methyltransferase SUV39H1 was significantly elevated in human colon carcinoma compared with normal colon tissues. Using a mouse colon carcinoma model, we further determined that tumor-infiltrating CTLs in the colon tumor microenvironment have high expression of SUV39H1. To target SUV39H1 in the tumor microenvironment, a virtual chemical library was screened on the basis of the SET (suppressor of variegation 3–9, enhancer of zeste and trithorax) domain structure of the human SUV39H1 protein. Functional enzymatic activity assa...
Oligonucleotide-based agents have the potential to treat or cure almost any disease, and are one ... more Oligonucleotide-based agents have the potential to treat or cure almost any disease, and are one of the key therapeutic drug classes of the future. Bioconjugated oligonucleotides, a subset of this class, are emerging from basic research and being successfully translated to the clinic. In this review, we first briefly describe two approaches for inhibiting specific genes using oligonucleotides-antisense DNA (ASO) and RNA interference (RNAi)followed by a discussion on delivery to cells. We then summarize and analyze recent developments in bioconjugated oligonucleotides including those possessing GalNAc, cell penetrating peptides, αtocopherol, aptamers, antibodies, cholesterol, squalene, fatty acids, or nucleolipids. These novel conjugates provide a means to enhance tissue targeting, cell internalization, endosomal escape, target binding specificity, resistance to nucleases, and more. We next describe those bioconjugated oligonucleotides approved for patient use or in clinical trials. Finally, we summarize the state of the field, describe current limitations, and discuss future prospects. Bioconjugation chemistry is at the centerpiece of this therapeutic oligonucleotide revolution, and significant opportunities exist for development of new modification chemistries, for mechanistic studies at the chemical-biology interface, and for translating such agents to the clinic.
Solid-state nanopores are an emerging biosensor for nucleic acid and protein characterization. Fo... more Solid-state nanopores are an emerging biosensor for nucleic acid and protein characterization. For use in a clinical setting, solid-state nanopore sensing requires sample preparation and purification, fluid handling, a heating element, electrical noise insulators, and an electrical readout detector, all of which hamper its translation to a point-of-care diagnostic device. A standalone microfluidic-based nanopore device is described that combines a bioassay reaction/purification chamber with a solid-state nanopore sensor. The microfluidic device is composed of the high-temperature/solvent resistance Zeonex plastic, formed via micromachining and heat bonding, enabling the use of both a heat regulator and a magnetic controller. Fluid control through the microfluidic channels and chambers is controlled via fluid port selector valves and allows up to eight different solutions. Electrical noise measurements and DNA translocation experiments demonstrate the integrity of the device, with performance comparable to a conventional stand-alone nanopore setup. However, the microfluidic-nanopore setup is superior in terms of ease of use. To showcase the utility of the device, single molecule detection of a DNA polymerase chain reaction product, after magnetic bead DNA separation, is accomplished on-chip.
The translation of biomaterial based and regenerative therapies from the laboratory to patients i... more The translation of biomaterial based and regenerative therapies from the laboratory to patients involves multiple challenges. One of the most pressing challenges is the educational one: to train a cohort of scientists and engineers capable of translating their discoveries from bench to market to clinic. To meet this need, translational training programs are being implemented globally at universities and as partnerships between universities and corporations. In this perspective, we describe two translational NIH T32 graduate and postgraduate training programs that augment the traditional approach to training early stage scientists and engineers. At the graduate level, Boston University developed and implemented the Translational Research in Biomaterials (TRB) predoctoral training program. At the postgraduate level, Rutgers, The State University of New Jersey, developed and implemented the Translational Research in Regenerative Medicine (TRRM) program for postdoctoral training. These programs are motivated by the need for training in translational research in the biomedical field, by young scientists' requests for such training, and by the fundamental challenges facing future discovery and clinical implementation of biomaterialbased technologies. The TRB program immerses trainees in the concept of translating an idea from the research laboratory to the clinic, introduces them to the challenges of such an endeavor, provides discussions with relevant faculty (for example, with businesses, patient care, or clinical trial experience), and educates them in the critical areas required for their future careers. Similarly, the TRRM program emphasizes translational research and the concept of "training without borders," which enables collaborations across several geographically dispersed institutions so as to make regional experts accessible regardless of where they are located physically. Both programs promote interdisciplinary research, expose young scientists and engineers to challenges outside of their specialty, and build interpersonal skills for cross-disciplinary communication. The TRB program focuses on quantitative science and engineering courses, together with translation-based courses in clinical trials and business. The TRRM program focuses on broadening the horizon of its trainees through exposure to a wider network of mentors than traditional postdoctoral *
A guidebook and reference for detecting and characterizing proteins at the single-molecule level ... more A guidebook and reference for detecting and characterizing proteins at the single-molecule level using nanopores.
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Papers by Mark Grinstaff