Investigation of physical and biological properties of polypyrrole nanotubes–chitosan nanocomposites

Recent advances of polypyrrole conducting polymer film for biomedical application: Toward a viable platform for cell-microbial interactions

Polypyrrole (PPy) is one of the most studied conductive polymers due to its electrical conductivity and biological properties, which drive the possibility of numerous applications in the biomedical area. The physical-chemical features of PPy allow the manufacture of biocompatible devices, enhancing cell adhesion and proliferation. Furthermore, owing to the electrostatic interactions between the negatively charged bacterial cell wall and the positive charges in the polymer structure, PPy films can perform an effective antimicrobial activity. PPy is also frequently associated with biocompatible agents and antimicrobial compounds to improve the biological response. Thus, this comprehensive review appraised the available evidence regarding the PPy-based films deposited on metallic implanted devices for biomedical applications. We focus on understanding key concepts that could influence PPy attributes regarding antimicrobial effect and cell behavior under in vitro and in vivo settings. Furthermore, we unravel the several agents incorporated into the PPy film and strategies to improve its functionality. Our findings suggest that incorporating other elements into the PPy films, such as antimicrobial agents, biomolecules, and other biocompatible polymers, may improve the biological responses. Overall, the basic properties of PPy, when combined with other composites, electrostimulation techniques, or surface treatment methods, offer great potential in biocompatibility and/or antimicrobial activities. However, challenges in synthesis standardization and potential limitations such as low adhesion and mechanical strength of the film must be overcome to improve and broaden the application of PPy film in biomedical devices.

Storage stability and in vitro digestion of apigenin encapsulated in Pickering emulsions stabilized by whey protein isolate–chitosan complexes

Few studies have investigated the encapsulation of apigenin in solid particle-stabilized emulsions. In this work, Pickering emulsions containing apigenin and stabilized by whey protein isolate-chitosan (WPI-CS) complexes were created to enhance the bioavailability of apigenin. Different lipids including medium-chain triglycerides (MCTs), ethyl oleate (EO), and corn oil (CO) were selected to fabricate lipid-based delivery systems. The microstructure of the Pickering emulsions, as revealed by optical and cryo-scanning electron microscopies, showed that the oil droplets were dispersed evenly and trapped by a three-dimensional network formed by the WPI-CS complexes, which was further confirmed by rheology properties. After 30 days of storage, Pickering emulsions with MCTs achieved the highest apigenin retention rate, exhibiting 95.05 ± 1.45% retention when stored under 4°C. In vitro gastrointestinal tract experiments indicated that the lipid types of the emulsions also affected the lipid digestion and release rate of apigenin. Pickering emulsions with MCTs achieved a higher bioaccessibility compared to that of the other two emulsions (p < 0.01). These results indicate that the delivery system of Pickering emulsions with MCTs stabilized by WPI-CS complexes offers good storage stability and improved bioaccessibility of apigenin.

Surface Functionalized Polyaniline Nanofibers:Chitosan Nanocomposite for Promoting Neuronal-like Differentiation of Primary Adipose Derived Mesenchymal Stem Cells and Urease Activity

Bioscaffolds having electrically conducting polymers (CPs) have become increasingly relevant in tissue engineering (TE) because of their ability to regulate conductivity and promote biological function. With this in mind, the current study shows a conducting polyaniline nanofibers (PNFs) dispersed chitosan (Ch) nanocomposites scaffold with a simple one-step surface functionalization approach using glutaraldehyde for potential neural regeneration applications. According to the findings, 4 wt % PNFs dispersion in Ch matrix is an optimal concentration for achieving desirable biological functions while maintaining required physicochemical properties as evidenced by SEM, XRD, current-voltage (I-V) measurement, mechanical strength test, and in vitro biodegradability test. Surface chemical compositional analysis using XPS and ATR FT-IR confirms the incorporation of aldehyde functionality after functionalization, which is corroborated by surface energy calculations following the Van Oss-Chaudhury-Good method. Surface functionalization induced enhancement in surface hydrophilicity in terms of the polar component of surface energy (γ_i^AB) from 6.35 to 12.54 mN m^-1 along with an increase in surface polarity from 13.61 to 22.54%. Functionalized PNF:Ch scaffolds demonstrated improvement in enzyme activity from 67 to 94% and better enzyme kinetics with a reduction of Michaelis constants (K_m) from 21.55 to 13.81 mM, indicating favorable protein-biomaterial interactions and establishing them as biologically perceptible materials. Surface functionalization mediated improved cell-biomaterial interactions led to improved viability, adhesion, and spreading of primary adipose derived mesenchymal stem cells (ADMSCs) as well as improved immunocompatibility. Cytoskeletal architecture assessment under differentiating media containing 10 ng/mL of each basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) revealed significant actin remodeling with neurite-like projections on the functionalized scaffolds after 14 days. Immunocytochemistry results showed that more than 85% of cells expressed early neuron specific β III tubulin protein on the functionalized scaffolds, whereas glial fibrillary acidic protein (GFAP) expression was limited to approximately 40% of cells. The findings point to the functionalized nanocomposites' potential as a smart scaffold for electrically stimulated neural regeneration, as they are flexible enough to be designed into microchanneled or conduit-like structures that mimic the microstructures and mechanical properties of peripheral nerves.

Influence of magnetic field on morphological structures and physiological characteristics of bEnd.3 cells cultured on polypyrrole substrates

This paper employs a spin-coated method to construct conductive polypyrrole (PPy) substrates which present superior properties for controlling the morphological structures and functions of bEnd.3 cells. The PPy substrates with a homogeneous particle size, uniform distribution and proper roughness show enhanced hydrophilic characteristics and improve cell adhesion to the substrates. The changes in the mechanical properties of cells and the responses to the designed substrates and magnetic field are also explored. Due to the synergistic effect between the magnetic field and the conductive PPy substrate, the cells cultured in such an environment exhibit applanate shapes with more branches and enhanced cell viability. In addition, the cells preferentially extend along the magnetic field direction. The mechanical characteristics of cells change significantly under varying magnetic intensity stimulations (5–16 mT). The satisfying effect on cells' morphology and outgrowth is acquired at the magnetic intensities of 9–10 mT and duration of 20 min, compared with other stimulated groups, while retaining cell viability. Moreover, the cells express higher adhesion up to 5.2 nN. The results suggest that the application of the PPy substrates and magnetic field is a promising candidate for the protection of neurovascular units and treatment of neurological diseases.

The combination of magnetic stimulation and polypyrrole (PPy) substrates regulate the bEnd.3 cells mechanical and physical characterizations.

Synthesis of silver-anchored polyaniline–chitosan magnetic nanocomposite: a smart system for catalysis

A novel and smart four component system composed of chitosan, polyaniline, magnetite and silver was exploited for catalysis.

Simultaneous inhibition of EGFR and MET receptors with phytochemical conjugated magnetic nanocarriers: in silico and in vitro study

Beta-sitosterol,dl-alpha-tocopherol and 1,3,8-P-menthatriene ofMentha piperitaconjugated superparamagnetic iron-oxide nanoparticles (SPIONs) potentially inhibit EGFR and MET expressing cancer cells.