Electrodynamic assisted self-assembled fibrous hydrogel microcapsules: a novel 3D in vitro platform for assessment of nanoparticle toxicity

Chitin Nanofibrils Enabled Core-Shell Microcapsules of Alginate Hydrogel

An engineered 3D architectural network of the biopolymeric hydrogel can mimic the native cell environment that promotes cell infiltration and growth. Among several bio-fabricated hydrogel structures, core-shell microcapsules inherit the potential of cell encapsulation to ensure the growth and transport of cells and cell metabolites. Herein, a co-axial electrostatic encapsulation strategy is used to create and encapsulate the cells into chitin nanofibrils integrated alginate hydrogel microcapsules. Three parameters that are critical in the electrostatic encapsulation process, hydrogel composition, flow rate, and voltage were optimized. The physicochemical characterization including structure, size, and stability of the core-shell microcapsules was analyzed by scanning electron microscope (SEM), FTIR, and mechanical tests. The cellular responses of the core-shell microcapsules were evaluated through in vitro cell studies by encapsulating NIH/3T3 fibroblast cells. Notably, the bioactive microcapsule showed that the cell viability was found excellent for more than 2 weeks. Thus, the results of this core-shell microcapsule showed a promising approach to creating 3D hydrogel networks suitable for different biomedical applications such as in vitro tissue models for toxicity studies, wound healing, and tissue repair.

Incorporating nanoconfined chitin-fibrils in poly (ε-caprolactone) membrane scaffolds improves mechanical and chemical properties for biomedical application

Engineered composite scaffolds composed of natural and synthetic polymers exhibit cooperation at the molecular level that closely mimics tissue extracellular matrix's (ECM) physical and chemical characteristics. However, due to the lack of smooth intermix capability of natural and synthetic materials in the solution phase, bio-inspired composite material development has been quite challenged. In this research, we introduced new bio-inspired material blending techniques to fabricate nanofibrous composite scaffolds of chitin nanofibrils (CNF), a natural hydrophilic biomaterial and poly (ɛ-caprolactone) (PCL), a synthetic hydrophobic-biopolymer. CNF was first prepared by acid hydrolysis technique and dispersed in trifluoroethanol (TFE); and second, PCL was dissolved in TFE and mixed with the chitin solution in different ratios. Electrospinning and spin-coating technology were used to form nanofibrous mesh and films, respectively. Physicochemical properties, such as mechanical strength, and cellular compatibility, and structural parameters, such as morphology, and crystallinity, were determined. Toward the potential use of this composite materials as a support membrane in blood-brain barrier application (BBB), human umbilical vein endothelial cells (HUVECs) were cultured, and transendothelial electrical resistance (TEER) was measured. Experimental results of the composite materials with PCL/CNF ratios from 100/00 to 25/75 showed good uniformity in fiber morphology and suitable mechanical properties. They retained the excellent ECM-like properties that mimic synthetic-bio-interface that has potential application in biomedical fields, particularly tissue engineering and BBB applications.

Single-Micelle-Templated Synthesis of Hollow Barium Carbonate Nanoparticle for Drug Delivery

A laboratory-synthesized triblock copolymer poly(ethylene oxide-b-acrylic acid-b-styrene) (PEG-PAA-PS) was used as a template to synthesize hollow BaCO3 nanoparticles (BC-NPs). The triblock copolymer was synthesized using reversible addition–fragmentation chain transfer radical polymerization. The triblock copolymer has a molecular weight of 1.88 × 104 g/mol. Transmission electron microscopy measurements confirm the formation of spherical micelles with a PEG corona, PAA shell, and PS core in an aqueous solution. Furthermore, the dynamic light scattering experiment revealed the electrostatic interaction of Ba2+ ions with an anionic poly(acrylic acid) block of the micelles. The controlled precipitation of BaCO3 around spherical polymeric micelles followed by calcination allows for the synthesis of hollow BC-NPs with cavity diameters of 15 nm and a shell thickness of 5 nm. The encapsulation and release of methotrexate from hollow BC-NPs at pH 7.4 was studied. The cell viability experiments indicate the possibility of BC-NPs maintaining biocompatibility for a prolonged time.