Glass Transition in Crosslinked Nanocomposite Scaffolds of Gelatin/Chitosan/Hydroxyapatite

Water-soluble chitosan-g-PMAm (PMAA)-Bodipy probes prepared by RAFT methods for the detection of Fe3+ ion

It is a challenge to achieve the fully water-soluble chitosan. In this work, water-soluble chitosan-based probes were obtained by the following steps: boron-dipyrrolemethene (BODIPY)-OH was synthesized, and then BODIPY-OH was halogenated to BODIPY-Br. Afterwards, BODIPY-Br reacted with carbon disulfide and mercaptopropionic acid to obtain BODIPY-disulfide. BODIPY-disulfide was introduced to chitosan via amidation reaction to obtain fluorescent chitosan-thioester (CS-CTA); it is employed as the macro-initiator. Methacrylamide (MAm) was grafted onto chitosan fluorescent thioester through reversible addition-fragmentation chain transfer (RAFT) polymerization method. Thus, a water-soluble macromolecular probe (CS-g-PMAm) with chitosan as the main chain and PMAm as long-branched chains was obtained. It greatly improved the solubility in pure water. The thermal stability was reduced slightly, and the stickiness was greatly reduced and the samples displayed the characteristics of liquid. CS-g-PMAm could detect Fe³⁺ in pure water. By the same method, CS-g-PMAA (CS-g-Polymethylacrylic acid) was synthesized and investigated as well.

Drug release study of the chitosan-based nanoparticles

Recently, multifunctional drug delivery systems (DDSs) have been designed to provide a comprehensive approach with multiple functionalities, including diagnostic imaging, targeted drug delivery, and controlled drug release. Chitosan-based drug nanoparticles (CSNPs) systems are employed as diagnostic imaging and delivering the drug to particular targeted sites in a regulated manner. Drug release is an important factor in ensuring high reproducibility, stability, quality control of CSNPs, and scientific-based for developing CSNPs. Several factors influence drug release from CSNPs, including composition, composition ratio, ingredient interactions, and preparation methods. Early, CSNPs were used for improving drug solubility, stability, pharmacokinetics, and pharmacotherapeutics properties. Chitosan has been developed toward a multifunctional drug delivery system by exploring positively charged properties and modifiable functional groups. Various modifications to the polymer backbone, charge, or functional groups will undoubtedly affect the drug release from CSNPs. The drug release from CSNPs has a significant influence on its therapeutic actions. Our review's objective was to summarize and discuss the relationship between the modification in CSNPs as multifunctional delivery systems and drug release properties and kinetics of the drug release model. Kinetic models help describe the release rate, leading to increased efficiency, accuracy, the safety of the dose, optimizing the drug delivery device's design, evaluating the drug release rate, and improvement of patient compatibility. In conclusion, almost all CSNPs showed bi-phasic release, initial burst release drug in a particular time followed controlled manner release in achieving the expected release, stimuli external can be applied. CSNPs are a promising technique for multifunctional drug delivery systems.

Polyetheretherketone and Its Composites for Bone Replacement and Regeneration

In this article, recent advances in the development, preparation, biocompatibility and mechanical properties of polyetheretherketone (PEEK) and its composites for hard and soft tissue engineering are reviewed. PEEK has been widely employed for fabricating spinal fusions due to its radiolucency, chemical stability and superior sterilization resistance at high temperatures. PEEK can also be tailored into patient-specific implants for treating orbital and craniofacial defects in combination with additive manufacturing process. However, PEEK is bioinert, lacking osseointegration after implantation. Accordingly, several approaches including surface roughening, thin film coating technology, and addition of bioactive hydroxyapatite (HA) micro-/nanofillers have been adopted to improve osseointegration performance. The elastic modulus of PEEK is 3.7-4.0 GPa, being considerably lower than that of human cortical bone ranging from 7-30 GPa. Thus, PEEK is not stiff enough to sustain applied stress in load-bearing orthopedic implants. Therefore, HA micro-/nanofillers, continuous and discontinuous carbon fibers are incorporated into PEEK for enhancing its stiffness for load-bearing applications. Among these, carbon fibers are more effective than HA micro-/nanofillers in providing additional stiffness and load-bearing capabilities. In particular, the tensile properties of PEEK composite with 30wt% short carbon fibers resemble those of cortical bone. Hydrophobic PEEK shows no degradation behavior, thus hampering its use for making porous bone scaffolds. PEEK can be blended with hydrophilic polymers such as polyglycolic acid and polyvinyl alcohol to produce biodegradable scaffolds for bone tissue engineering applications.

Synthesis of biogenic chitosan-functionalized 2D layered MoS2 hybrid nanocomposite and its performance in pharmaceutical applications: In-vitro antibacterial and anticancer activity

A bacterial and viral infection causes life threatening diseases owing to the abuse of antibiotics and the development of antibiotic resistance microbes. Currently, biopolymers have been considered as the most promising materials in the medical field. Herein, the biogenic chitosan-functionalized MoS₂ nanocomposite was prepared by the hydrothermal method with the liquid exfoliation process. The X-ray diffraction (XRD) results of chitosan-MoS₂ hybrid nanocomposite revealed that MoS₂ nanoparticle was found to be 42 nm with a hexagonal crystal structure. FTIR and Raman spectrum revealed that the nitrogen functionalities in the chitosan interacted with MoS₂ to form the nanocomposite. The XPS spectrum of chitosan-MoS₂ nanocomposite confirms that C, N, O, Mo, and S exist in the nanocomposite. Thermal gravimetric analysis (TGA) and Differential thermal analysis (DTA) analysis showed that the chitosan-MoS₂ nanocomposite has higher thermal stability up to 600 °C. In the antibacterial application the chitosan-MoS₂ hybrid nanocomposite shows zones of inhibition against S. aureus as 22, 28, and 32 mm, and against E. coli as 26, 30, and 35 mm. In the anticancer analysis, chitosan-MoS₂ hybrid nanocomposites showed a maximum cell inhibition of 65.45% at 100 μg/mL^-1, resulting in the most significant MCF-7 cell inhibition.