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Introduction Emergence of antibiotic resistance in bacteria is a complicated issue, especially when treating infectious immunodeficiency related diseases. In recent years, when compared to bulk materials, nanomaterials (NMs) with specific antibacterial activities have played a novel role in treating bacterial infections. Among NMs, quantum dots (QDs), specifically carbon containing QDs including graphene oxide QD (GOQD), graphene QD (GQD), and carbon QD (CQD), have demonstrated bacteriostatic and bactericidal activities via photodynamic (PD) effects against antibiotic resistant bacteria under a certain wavelength of light. Area covered In this mini-review, recent advances and challenges related to antibacterial and biocompatibility activities of modified GQD, GOQD, CQD, and carbon nanotubes (CNTs) are discussed. Expert opinion Lower stability and biocompatibility of QDs at higher doses in physiological conditions are major disadvantages. In this regard, functionalization of these QDs can result in appropriate bactericidal, biocompatibility, and biodegradability properties. In the case of CNTs including single-wall carbon nanotube (SWCNTs) and multiwall carbon nanotube (MWCNTs), aspect ratio (AR) is a determinant factor for the antibacterial value. Moreover, MWCNTs show a lower antibacterial ability compared to SWCNTs, which can be improved by modifying their surface.

Given the great demand for biopolymer and protein-based products from renewable resources, synthesis of a keratin-based hydrogel is presented herein. In this work, a novel hydrogel of poly(γ-glutamic acid) (γ-PGA) and keratin was synthesized through facile EDC·HCl/HOBt chemistry. Since keratin main chain is rich in amino side groups, carboxyl groups in γ-PGA were crosslinked with multi terminated amine groups in keratin. In the following, the hydrogel characteristics, including swelling ratio (2010% at molar ratio of HOBt/EDC = 0.105), in vitro degradation and mass loss (about 20% at day 21 for the aforementioned sample), chemical decomposition and the rheological properties were investigated. The chemical activator agents, enhanced the elastic modulus of swollen hydrogel from around 1000 to 4000 Pa by increasing the crosslinking degree. Despite good biocompatibility for cell growth, some kind of self-assembled keratin hydrogels are not suitable for microscopic observation while the γ-PGA-Keratin hydrogel in our study is transparent. The γ-PGA-Keratin hydrogels possess significant features of rapid hydrogel formation in seconds, maximum swelling ratio of about 2500% maximum elastic modulus (stiffness) of about 4.5 kPa (for the swollen sample) with controllable matrix pore size. For further application, the biocompatibility of the γ-PGA-Keratin hydrogel was assessed by live/dead assay. Recent studies have demonstrated the effect of hydrogel porosity, water absorbing and stiffness on cell spreading, proliferation and differentiation of mesenchymal stem cells. Bone marrow mesenchymal stem cells could be differentiated into various cell fates depending on the elastic modulus of materials they are cultured on. We carried out a statistical study (to skip the cell work labor) to predetermine the proper working span in which we can gain a hydrogel to cover all features needed to be applied for some application like cartilage repair.

This paper examines the relationship between rheology and the qualitative appearance of dried, mica-based paint coatings used in the aerospace industry. The goal is to identify key rheological characteristics indicative of poor coating visual appearance, providing a screening tool to identify unsatisfactory paint formulations. Four mica paints were studied, having coating visual appearances ranging from very poor to very good. Strain sweeps indicated that the poor-quality paints have a smaller % strain midpoint in the linear visco-elastic range; while the good-quality paints have a lower G’/G” cross-over point in frequency sweeps. Thixotropy experiments utilizing single and multiple-loop hysteresis cycles plotting shear stress as a function of shear rate showed that the base mica paints with good appearance had nearly constant, reversible profiles in the forward and the backward directions; while the mica paints with poor appearance were irreversible with a noticeable gradual change in shear stress as more loops are run. The difference in area between the forward and the reverse curves was determined, leading to a quantifiable criterion that can differentiate good paints from poor paints with significance testing. This work would establish the first rheology model using hysteresis loops to predict the visual properties of mica-based paints.

International audience; Threading intercalators are a novel class of materials that carry two substituents along the diagonal positions of an aromatic ring. When bound to DNA, these substituents project out in DNA grooves. Tetranuclear complexes appear to be promising threading intercalators for developing therapeutics against cancer and viral infections that require high nucleic acid binding affinity. The objective of this work was to prepare the thiosemicarbazone scaffold ligand [4-ClC6H4CHN=NC(S)NHPh] and tetranuclear cyclopalladated complex [Pd(4-ClC6H4CHN=NC(S)NHPh)4] and to characterize the compounds by elemental analysis, 1D and 2D NMR, HRMS, and IR spectroscopy. The calf thymus DNA (CT-DNA) binding properties of the compounds were investigated in vitro under simulated physiological conditions using UV-vis spectroscopy, emission spectral titration, methylene blue competitive binding, circular dichroism, DNA thermal denaturation, DNA binding, and coronavirus interactions using molecular simulation. The compounds showed cytotoxic effect against both human breast (MCF-7) and colorectal (HCT116) cancer cells in a dose-dependent manner. We demonstrated that the compounds are promising for DNA threading intercalation binders with large DNA binding constants on the order of 107 M1 magnitude.

Cancer stem cells (CSCs) are a subpopulation of cells that can initiate, self-renew, and sustain tumor growth. CSCs are responsible for tumor metastasis, recurrence, and drug resistance in cancer therapy. CSCs reside within a niche maintained by multiple unique factors in the microenvironment. These factors include hypoxia, excessive levels of angiogenesis, a change of mitochondrial activity from aerobic aspiration to aerobic glycolysis, an upregulated expression of CSC biomarkers and stem cell signaling, and an elevated synthesis of the cytochromes P450 family of enzymes responsible for drug clearance. Antibodies and ligands targeting the unique factors that maintain the niche are utilized for the delivery of anticancer therapeutics to CSCs. In this regard, nanomaterials, specifically nanoparticles (NPs), are extremely useful as carriers for the delivery of anticancer agents to CSCs. This review covers the biology of CSCs and advances in the design and synthesis of NPs as a carrier in targeting cancer drugs to the CSC subpopulation of cancer cells. This review includes the development of synthetic and natural polymeric NPs, lipid NPs, inorganic NPs, self-assembling protein NPs, antibody-drug conjugates, and extracellular nanovesicles for CSC targeting.

This work describes the synthesis of a novel organic–inorganic nanocomposite membrane via an efficient one-pot approach of co-deposition of octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA–POSS) and polyoxometalate (POSS–Mo36) onto a support membrane. The structure and morphology of the thin film nanocomposite (TFN) membranes were characterized by FT-IR spectroscopy, atomic force microscopy (AFM), energy-dispersive X-ray analysis (EDX), and scanning electron microscopy (SEM). In addition, the effect of POSS–Mo36 on the performance of the thin film nanocomposite (TFN) membranes was investigated in a forward osmosis (FO) process. Experimental results demonstrate the enhanced desalination performance of the synthesized as compared to thin-film composite (TFC) polyamide membranes.

Scar formation is a common consequence of skin injuries that lead to a wide range of adverse effects including physical deformities and psychological disorders. Studies demonstrate that mammalian fetal skin in early gestation is capable of regenerating itself after injury without any scar formation. A number of potential therapies have been developed to reduce scar formation in cutaneous wounds based on differences between the process of adult and fetal wound healing. The ideal approach to eliminate scar formation after skin injury is to use a pro-regenerative matrix along with growth factors and cell types that induce regeneration rather than repair. This work provides a comprehensive review of engineering approaches to scar-free wound healing with emphasis on the use of pro-regenerative biomaterials to minimize scar formation in skin injuries. IMPACT STATEMENT: Millions of people every year develop scars in response to skin injuries after surgery, trauma, or burns with significant undesired physical and psychological effects. This review provides an update on engineering strategies for scar-free wound healing and discusses the role of different cell types, growth factors, cytokines, and extracellular components in regenerative wound healing. The use of pro-regenerative matrices combined with engineered cells with less intrinsic potential for fibrogenesis is a promising strategy for achieving scar-free skin tissue regeneration.

Octavinyl polyhedral oligomeric silsesquioxane (POSS) was polymerized on the surface of Fe3O4 nanoparticles (NPs) and then the NPs were functionalized with carboxylic acid groups using thiol-ene click reactions with thioglycolic acid. The as-prepared Fe3O4@POSS-COOH magnetic hybrid NPs had mesoporous structures with an average particle diameter of 15 nm and a relatively high specific surface area of 447 m2·g−1. Experimental results showed that 4 mg of Fe3O4@POSS-COOH NPs efficiently adsorbed and removed methylene blue from water at 5 min. This is due to the presence of both carboxylic acid and pendant vinyl groups on the Fe3O4@POSS-COOH NPs. These NPs could be easily withdrawn from water within a few seconds under moderate magnetic field and showed high stability in acid and alkaline aqueous mediums.

A green and simple process for preparing the polyethylene glycol passivated fluorescent carbon dots (CDs-PEG) have been studied by a microwave pyrolysis method, using gelatin and PEG as starting materials. This method is very effective for development of carbon-based quantum dots from gelatin with high quantum yield (QY). The synthesized CDs-PEG were found to emit blue photoluminescence (PL) with a maximum QY of 34%. At the following research, we investigated the effect of the presence of PEG on PL intensity, and the result showed that CDs-PEG becomes stronger PL properties than pure CDs from gelatin. The synthesized CDs-PEG were characterized by FTIR, TEM, UV-vis, PL, zeta potential and XRD analyses. The anticancer performance of developed CDs-PEG was evaluated by in vitro tests such as MTT assay and fluorescence microscopy analyses. The examination of CDs-PEG as an anti-cancer drug nanocarrier for methotrexate (MTX) illustrated a better antitumor efficacy than free MTX due to its enhanced nuclear delivery in vitro, which resulting in highly effective tumour growth inhibition and improving targeted cancer therapy in clinical medicine.

Engineering approaches that mimic the process of fetal development have the potential to regenerate the zonal organization of articular cartilage. The objective of this study was to investigate the effect of sequential addition of zone-specific growth factors such as bone morphogenetic protein (BMP)-7, insulin-like growth factor (IGF)-1, and Indian hedgehog (IHH) to transforming growth factor (TGF)-β1-supplemented chondrogenic medium on zonal differentiation of human mesenchymal stem cells (hMSCs) encapsulated in an articular cartilage-derived matrix. First, fetal or adult bovine articular cartilage was decellularized, digested, and methacrylate functionalized to produce an injectable macromer (CarMa, f-CarMa for fetal, a-CarMa for adult) for encapsulation of hMSCs. Next, the optimum matrix source and initial cell density for chondrogenic differentiation of hMSCs to the superficial and calcified zone phenotypes were determined by encapsulation of the cells in CarMa hydrogel and incubated in chondrogenic medium/TGF-β1 supplemented with BMP-7 and IHH, respectively. Then, the encapsulated hMSCs were preexposed to BMP-7-supplemented chondrogenic medium/TGF-β1 and the effect of sequential addition of IGF-1 and IHH to the medium on the expression of zone-specific markers was investigated. According to the results, f-CarMa and high cell density enhanced differentiation of the encapsulated hMSCs to the superficial zone phenotype, whereas a-CarMa and low cell density enhanced differentiation to the calcified zone. The addition of IGF-1 to the chondrogenic medium/TGF-β1 stimulated differentiation of the encapsulated hMSCs, preexposed to BMP-7, to the middle zone phenotype. The addition of IHH to the chondrogenic medium/TGF-β1 stimulated maturation of the encapsulated hMSCs, preexposed to BMP-7 and IGF-1, to the calcified zone phenotype. The results are potentially useful for engineering injectable, cellular hydrogels for regeneration of full-thickness articular cartilage. IMPACT STATEMENT: The higher regenerative capacity of fetal articular cartilage compared with the adult is rooted in differences in cell density and matrix composition. We hypothesized that the zonal organization of articular cartilage can be engineered by encapsulation of mesenchymal stem cells in a single superficial zone-like matrix followed by sequential addition of zone-specific growth factors within the matrix, similar to the process of fetal cartilage development. The results demonstrate that the zonal organization of articular cartilage can potentially be regenerated using an injectable, monolayer cell-laden hydrogel with sequential release of growth factors.

IntroductionThe objective was to create multilayer cellular constructs using fetal or adult, decellularized articular cartilage in particulate form as microcarriers for expansion and fusion of mesenchymal stem cells (MSCs) to regenerate the stratified structure of articular cartilage.MethodsPorous microparticles (CMPs) generated from decellularized fetal or adult bovine articular cartilage were used as microcarriers for expansion of human MSCs. The CMP expanded MSCs (CMP-MSCs) were used to generate injectable hydrogels or preformed multilayer constructs for articular cartilage regeneration. In the injectable approach, CMP-MSCs were suspended in alginate gel, crosslinked with calcium chloride, and incubated in chondrogenic medium to generate an injectable regenerative construct. In the preformed approach, fetal or adult CMP-MSCs were suspended in a culture medium, allowed to settle sequentially by the force of gravity, and fused by incubation in chondrogenic medium to generate multilayer cell sheets. The constructs were characterized with respect to compressive modulus, cellularity, and expression of chondrogenic markers.ResultsHuman MSCs expanded on fetal or adult CMPs in basal medium maintained the expression of mesenchymal markers. The injectable CMP-MSCs hydrogels had significantly higher expression of chondrogenic markers and compressive modulus after four weeks incubation in chondrogenic medium compared to MSCs directly encapsulated in alginate gel; preformed CMP-MSCs cell sheets had significantly higher compressive modulus and expression of chondrogenic markers compared to MSCs in the pellet culture.ConclusionThe preformed cell sheet approach is potentially useful for creating multilayer constructs by sequential gravitational settling of CMP-MSCs to mimic the stratified structure of articular cartilage.Insight, Innovation, IntegrationThis work described a novel approach to recreate the zonal structure of articular cartilage. Human MSCs were expanded on porous microcarrier beads generated from decellularized fetal or adult bovine articular cartilage. The cell-seeded microbeads were fused by gravitational settling to form mono- or bi-layer cell sheets. The cell sheets were cultured in chondrogenic medium to regenerate the articular cartilage tissue. The in vitro regenerated tissue had higher compressive modulus and expression of chondrogenic markers compared to the MSC pellet culture.

© 2021 Elsevier B.V.Polyphenol-based materials have attracted wide-spread interest from academic and industrial communities because of their unique structure and physicochemical properties. Tannic acid (TA), as a polyphenolic phytochemical with high level of galloyl groups, interacts with various substances (proteins, polysaccharides, and metals) through several modes including hydrogen bonding, hydrophobic and electrostatic interactions. Such hybrid or hybrid-like systems allow the preparation of various advanced materials with promising applications in medicine. In this review, we highlight the recent advances of TA-incorporated materials in medical applications including drug delivery, tissue engineering, treatment of infections, cancer therapy and biosensing. We believe that this review provides further investigation and development of TA as a promising natural compound to design new versatile architectures in the field of materials science.

Regeneration of bone tissue requires novel load bearing, biocompatible materials that support adhesion, spreading, proliferation, differentiation, mineralization, ECM production and maturation of bone-forming cells. Polycaprolactone (PCL) has many advantages as a biomaterial for scaffold production including tuneable biodegradation, relatively high mechanical toughness at physiological temperature. Electrospinning produces nanofibrous porous matrices that mimic many properties of natural tissue extracellular matrix with regard to surface area, porosity and fibre alignment. The biocompatibility and hydrophilicity of PCL nanofibres can be improved by combining PCL with other biomaterials to form composite scaffolds for bone regeneration. This work reviews the most recent research on synthesis, characterization and cellular response to nanofibrous PCL scaffolds and the composites of PCL with other natural and synthetic materials for bone tissue engineering.

Nanogels, or nanostructured hydrogels, are one of the most interesting materials in biomedical engineering. Nanogels are widely used in medical applications, such as in cancer therapy, targeted delivery of proteins, genes and DNAs, and scaffolds in tissue regeneration. One salient feature of nanogels is their tunable responsiveness to external stimuli. In this review, thermosensitive nanogels are discussed, with a focus on moieties in their chemical structure which are responsible for thermosensitivity. These thermosensitive moieties can be classified into four groups, namely, polymers bearing amide groups, ether groups, vinyl ether groups and hydrophilic polymers bearing hydrophobic groups. These novel thermoresponsive nanogels provide effective drug delivery systems and tissue regeneration constructs for treating patients in many clinical applications, such as targeted, sustained and controlled release.

Condensed polyhedral oligomeric silsesquioxane (POSS) family of materials are very attractive as a nanoscale drug delivery system in cancer therapy. This work describes a novel method for conjugation of poorly soluble anticancer drug paclitaxel (PTX) to octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt nanoparticles (OA-POSS NPs). The synthesized nanoconjugate of PTX and OA-POSS NPs (PTXn-OA-POSS8-n prodrug) was fully soluble in aqueous solution as compared to the free PTX.

Studies on nano-sized particles have been the range for the past 10–15 years. With rapid growth of metal oxide nanotechnologies during the last decades, the application of this material in the field of catalysis has become a substantial research area. In the past decades, the utilization of transition metal oxide nanoparticle catalysts for industrial application in the synthesis of important chemical intermediates has been investigated by industrial and academic communities. Compared to other catalysts, one of the outstanding properties of metal oxide nanoparticles in catalysis is represented by the high selectivity which allows discrimination within chemical groups and geometrical positions, favoring high yields of the desired product. This review is devoted to dealing with the application of transition metal oxide nanoparticles as catalyst for oxidations of sulfides, alcohols, olefins, and alkanes toward the synthesis of a variety of organic compounds, such as sulfoxides, aldehydes and ketones, carboxylic acids, epoxides and alcohols.

A combination of elastic poly(butylene succinate-co-ethylene terephthalate) and rigid nano-hydroxyapatite were used to prepare an in-situ synthesized nanocomposite mimicing bone structure. The microstructure, morphology and dispersion of nanoparticles in the nanocomposites were studied using 1H-NMR, SEM and TEM, respectively. Then, electrospinning method was used to produce nanofiber matrix with lowest fiber diameter. Presence of chemical bonds among nanoparticles and polymer leads to the excellent particle dispersion and solution phase stability. SEM results show that continuous and bead-free nanofibers were produced and incorporating nanoparticle slightly increased fibers diameter. Elastic modulus, tensile strength, crystallinity, hydrophilicity and hydrolytic degradability of resulted nanofiber increased with nanoparticle but elongation at break slightly decreased. Proliferation and osteogenic differentiation of human mesenchymal stem cell significantly improved by introducing nanoparticle which indicate that electrospun nanofibers could be used as scaffolds for bone tissue engineering. This article is protected by copyright. All rights reserved.

Clinically usable tissue-engineered constructs are currently limited due to their inability of forming microvascular networks necessary for adequate cellular oxygen and nutrient supply upon implantation. The aim of this study is to investigate the conditions necessary for microvascularization in a tissue-engineered construct using vascular endothelial growth factor (VEGF). The construct was made of gelatin methacrylate (GelMA) based cell-laden hydrogel system, which was then covalently linked with VEGF-mimicking peptide (AcQK), using human umbilical vein endothelial cells (HUVECs) as the model cell. The results of the mechanics and gene expression analysis indicated significant changes in mechanical properties and upregulation of vascular-specific genes. The major finding of this study is that the increased expression of vascular-specific genes could be achieved by employing AcQK in the GelMA based hydrogel system, leading to accelerated microvascularization. We conclude that GelMA with covalently-linked angiogenic peptide is a useful tissue engineered construct suitable for microvascularization. STATEMENT OF SIGNIFICANCE: (1) This study reports the conditions necessary for microvascularization in a tissue-engineered construct using vascular endothelial growth factor (VEGF). (2) The construct was made of gelatin methacrylate based cell-laden hydrogel system. (3) There is a significant change observed in mechanical properties and upregulation of vascular-specific genes, in particular CD34, when AcQK is used. (4) The major finding of this study is that the increased expression of vascular-specific genes, i.e., CD34 could be achieved by employing AcQK in the GelMA based hydrogel system, leading to accelerated microvascularization.

Palladium nanoparticles supported on Incompletely Condensed Polyhedral Oligomeric Silsesquioxane (IC-POSS) based poly (Acrylamide-co-Hydroxy ethyl methacrylate) as a novel nanohybrid catalyst were synthesized and characterized. This catalyst was found to be an efficient and reusable heterogeneous catalyst for the Heck reaction using water as the solvent in the absence of a phosphine ligand and phase transfer catalyst.

The objective of this work was to engineer self-assembled nanoparticles (NPs) for on-demand release of bone morphogenetic protein-2 (BMP2) and vascular endothelial growth factor (VEGF) in response to enzymes secreted by the migrating human mesenchymal stem cells (hMSCs) and human endothelial colony forming cells (ECFCs) to induce osteogenesis and vasculogenesis. Gene expression profiling experiments revealed that hMSCs and ECFCs, encapsulated in osteogenic/vasculogenic hydrogels, expressed considerable levels of plasminogen, urokinase plasminogen activator and its receptor uPAR, and tissue plasminogen activator. Therefore, the plasmin-cleavable lysine-phenylalanine-lysine-threonine (KFKT) was used to generate enzymatically cleavable NPs. The acetyl-terminated, self-assembling peptide glycine-(phenylalanine)3GFFF-ac and the plasmin-cleavable GGKFKTGG were reacted with the cysteine-terminated CGGK(Fmoc/MTT) peptide through the MTT and Fmoc termini, respectively. The difunctional peptide was conjugated to polyethylene glycol diacrylate (PEGDA) with molecular weights (MW) ranging from 0.5 to 7.5 kDa, and the chain ends of the PEG-peptide conjugate were terminated with succinimide groups. After self-assembly in aqueous solution, BMP2 was grafted to the self-assembled, plasmin-cleavable PEG-based (PxSPCP) NPs for on-demand release. The NPs' stability in aqueous solution and that of the grafted BMP2 were strongly dependent on PEG MW. P2SPCP NPs showed high particle size stability, BMP2 grafting efficiency, grafted protein stability, and high extent of osteogenic differentiation of hMSCs. The localized and on-demand release of BMP2 from PxSPCP NPs coencapsulated with hMSCs in the linear polyethylene glycol-co-lactide acrylate patterned hydrogel with microchannels encapsulating hMSCs + ECFCs and VEGF-conjugated nanogels resulted in the highest extent of osteogenic and vasculogenic differentiation of the encapsulated cells compared to directly added BMP2/VEGF. The on-demand release of BMP2 from PxSPCP NPs not only enhances osteogenesis and vasculogenesis but also potentially reduces many undesired side effects of BMP2 therapy in bone regeneration.

Nowadays, polymer reaction engineers seek robust and effective tools to synthesize complex macromolecules with well-defined and desirable microstructural and architectural characteristics. Over the past few decades, several promising approaches, such as controlled living (co)polymerization systems and chain-shuttling reactions have been proposed and widely applied to synthesize rather complex macromolecules with controlled monomer sequences. Despite the unique potential of the newly developed techniques, tailor-making the microstructure of macromolecules by suggesting the most appropriate polymerization recipe still remains a very challenging task. In the current work, two versatile and powerful tools capable of effectively addressing the aforementioned questions have been proposed and successfully put into practice. The two tools are established through the amalgamation of the Kinetic Monte Carlo simulation approach and machine learning techniques. The former, an intelligent modeling tool, is able to model and visualize the intricate inter-relationships of polymerization recipes/conditions (as input variables) and microstructural features of the produced macromolecules (as responses). The latter is capable of precisely predicting optimal copolymerization conditions to simultaneously satisfy all predefined microstructural features. The effectiveness of the proposed intelligent modeling and optimization techniques for solving this extremely important &lsquo, inverse&rsquo, engineering problem was successfully examined by investigating the possibility of tailor-making the microstructure of Olefin Block Copolymers via chain-shuttling coordination polymerization.

Resveratrol is a small molecule produced by various plants with a remarkable range of beneficial functions in animals. One of these is stimulating signaling pathways in adipose tissue that protect against obesity. Unfortunately, resveratrol suffers from poor bioavailability that inhibits its accumulation in target tissues, including fat, thus hindering the realization of its therapeutic potential. To address this, we are developing biodegradable microparticles as drug depots for controlled release of resveratrol within fat. In this study, resveratrol was encapsulated into poly(lactide-co-glycolide) microparticles using an oil-in-water emulsion/solvent evaporation technique. The oil phase consisted of resveratrol and poly(lactide-co-glycolide) dissolved in a mixture of dichloromethane and ethanol; meanwhile, the aqueous phase contained poly(vinyl alcohol) as the emulsifier. Increasing ethanol’s volume ratio increased resveratrol’s solubility in the oil phase and particle drug loading. The maximal loading achieved was 65 µg/mg (6.5%) and occurred when the ethanol to dichloromethane ratio was 1:3. Under these conditions, particles exhibited ruffled surfaces, which resulted in variable drug release over the first three days of a six-week release assay. By decreasing resveratrol and ethanol in the oil phase and increasing poly(vinyl alcohol) in the aqueous phase, smooth particles were achieved, but they suffered a 15–25-fold decrease in drug loading depending on size. Small particles exhibited higher drug loading and burst drug release compared to larger particles because of their higher specific surface area. Utilizing mild chemistry, we functionalized poly(vinyl alcohol) with fluorescein isothiocyanate and demonstrated that encapsulation of resveratrol in the particle decreases the amount of fluorescent polymer on the particle surface, suggesting resveratrol displaces the emulsifier during particle formation. Taken together, resveratrol can be encapsulated into poly(lactide-co-glycolide) microparticles, but it accumulates at the particle surface impacting drug loading, surface roughness, and drug release.

The objective of this work was to fabricate a rigid, resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone. Aligned peptide-functionalize nanofiber microsheets were generated with calcium phosphate (CaP) content similar to that of the natural cortical bone. Next, the CaP-rich fibrous microsheets were wrapped around a microneedle to form a laminated microtube mimicking the structure of an osteon. Then, a set of the osteon-mimetic microtubes were assembled around a solid rod and the assembly was annealed to fuse the microtubes and form a shell. Next, an array of circular microholes were drilled on the outer surface of the shell to generate a cortical bone-like scaffold with an interconnected network of Haversian- and Volkmann-like microcanals. The CaP content, porosity and density of the bone-mimetic microsheets were 240 wt%, 8% and 1.9 g/ml, respectively, which were close to that of natural cortical bone. The interconnected network of microcanals in the fused microtubes increased permeability of a model protein in the scaffold. The cortical scaffold induced osteogenesis and vasculogenesis in the absence of bone morphogenetic proteins upon seeding with human mesenchymal stem cells and endothelial colony-forming cells. The localized and timed-release of morphogenetic factors significantly increased the extent of osteogenic and vasculogenic differentiation of human mesenchymal stem cells and endothelial colony-forming cells in the cortical scaffold. The cortical bone-mimetic nature of the cellular construct provided balanced rigidity, resorption rate, osteoconductivity and nutrient diffusivity to support vascularization and osteogenesis.

There is a need to develop biodegradable polymers with tunable physical, mechanical, and biochemical properties. The objective of this work was to investigate the effect of chain microstructure and fumarate content on material properties of poly(butylene succinate-co-fumarate) (PBS-BF) copolymers synthesized by a three-step method of separate esterification of succinic acid (SA) and fumaric acid (FA) with butylene glycol (BG) followed by polycondensation of bis(4-hydroxy butyl) succinate (BS) and bis(4-hydroxy butyl) fumarate (BF) pre-homopolyesters. The material properties of the synthesized PBS-BF were compared with those of PBSF copolymers synthesized by a two-step method of esterification of SA and FA with BG followed by polycondensation. The synthesized copolymers were pressed and slowly or rapidly cooled into sheets and crosslinked with UV irradiation. The molecular and microstructure of the copolymers were characterized by 1H NMR, viscometry, and wide-angle x-ray diffraction. For a given fumarate fraction, the degree of randomness of PBS-BF copolymers was less than PBSF but PBS-BF degree of randomness increased with polycondensation reaction time of PBS and PBF pre-homopolyesters. The crosslinked copolymers were characterized with respect to gelation, thermal and mechanical properties, and degradation. Melting (Tm) and crystalline (Tc) temperatures of poly(butylene succinate) (PBS) increased by copolymerization with BF and the increase was proportional to the copolymer fumarate fraction. The rapidly-cooled and crosslinked PBS-BF30 copolymer with 30% fumarate fraction had highest modulus of 393 MPa and lowest elongation at break of 1.3% among all copolymers whereas the rapidly-cooled and uncrosslinked PBSF10 copolymer with 10% fumarate fraction had lowest modulus of 303 MPa and highest elongation at break of 160%. The uncrosslinked PBS polymer had 31% weight loss after 24 weeks whereas the slowly-cooled and crosslinked PBS-BF30 copolymer with 30% fumarate fraction had

Cell-laden hydrogels can regenerate lost, damaged or malfunctioning tissues. Clinical success of such hydrogels is strongly dependent on the ability to tune their chemical, physico-mechanical, and biological properties to a specific application. In particular, mimicking the intricate arrangement of cell-interactive ligands of natural tissues is crucial to proper tissue function. Natural extracellular matrix elements represent a unique source for generating such interactions. A plethora of extracellular matrix-based approaches have been explored to augment the regenerative potential of hydrogels. These efforts include the development of matrix-like hydrogels, hydrogels containing matrix-like molecules, hydrogels containing decellularized matrix, hydrogels derived from decellularized matrix, and decellularized tissues as reimplantable matrix hydrogels. Here we review the evolution, strengths and weaknesses of these developments from the perspective of creating tissue regenerating hydrogels., National Science Foundation (U.S.) (NSF Grant DMR1049381), National Science Foundation (U.S.) (NSF Grant Grant Nos. IIP- 1357109), National Science Foundation (U.S.) (NSF Grant CBET1403545), National Institutes of Health (U.S.) (NIH Grant No. AR063745), Pew Charitable Trusts, National Institutes of Health (U.S.) (NIH Grant No. 1R03EB017402-01), Fonds voor Wetenschappelijk Onderzoek--Vlaanderen (FWO) (Grant No. 1208715N), National Science Foundation (U.S.) (Grant No. 1208715N), National Science Foundation (U.S.) (NSF Grant IMMODGEL (602694)), National Institutes of Health (U.S.) (EB012597), National Institutes of Health (U.S.) (NIH grant AR057837), National Institutes of Health (U.S.) (NIH grant DE021468), National Institutes of Health (U.S.) (NIH grant HL099073), National Institutes of Health (U.S.) (NIH grant AI105024)

The azide–alkyne cycloaddition reaction was investigated under catalytic conditions involving a copper(II)—polyhedral oligomeric silsesquioxane (POSS)—bridged Schiff base. This material demonstrated a high catalytic activity in organic synthesis of 1,4-triazoles. No additive such as a base or a reductant was required. Finally, recoverability and reusability of the POSS-bridged Schiff base–Cu(II) catalyst was analyzed.

International audience; Traditional computational methods simulate the microstructure of polymer chains from input reaction conditions, but a need exists for predicting optimum reaction conditions in a computationally demanding multivariable space leading to the synthesis of predesigned microstructures and architectures. Herein, the intelligent Monte Carlo (IMC) approach, able to predict optimum reaction conditions for synthesizing copolymers with predefined, complex microstructures as input is introduced. This is rendered possible by a combination of kinetic Monte Carlo (KMC) simulation with artificial intelligence concepts, which enables a reasonably enhanced convergence to optimum reactions conditions. Chain shuttling polymerization is chosen as a first test case due to its complexity and the intricate multiblock microstructures that are formed; whose tailoring requires multiple parameters. The IMC approach locates optimum reaction conditions for the synthesis of olefinic multiblock copolymers with specific microstructures. This approach provides a new platform for identifying complex reaction conditions to “produce” and “tailor‐make” materials with precisely predefined microstructures and facilitates the development of meaningful structure‐property relationships.