Nanomaterials-incorporated polymeric microneedles for wound healing applications.

There is a growing and urgent need for developing novel biomaterials and therapeutic approaches for efficient wound healing. Microneedles (MNs), which can penetrate necrotic tissues and biofilm barriers at the wound and deliver active ingredients to the deeper layers in a minimally invasive and painless manner, have stimulated the interests of many researchers in the wound-healing filed. Among various materials, polymeric MNs have received widespread attention due to their abundant material sources, simple and inexpensive manufacturing methods, excellent biocompatibility and adjustable mechanical strength. Meanwhile, due to the unique properties of nanomaterials, the incorporation of nanomaterials can further extend the application range of polymeric MNs to facilitate on-demand drug release and activate specific therapeutic effects in combination with other therapies. In this review, we firstly introduce the current status and challenges of wound healing, and then outline the advantages and classification of MNs. Next, we focus on the manufacturing methods of polymeric MNs and the different raw materials used for their production. Furthermore, we give a summary of polymeric MNs incorporated with several common nanomaterials for chronic wounds healing. Finally, we discuss the several challenges and future prospects of transdermal drug delivery systems using nanomaterials-based polymeric MNs in wound treatment application.

Green and sustainable extraction of phycocyanin from Spirulina platensis by temperature-sensitive polymer-based aqueous two-phase system and mechanism study.

In this study, a sustainable and environmentally friendly method was developed for the enrichment and purification of phycocyanin from Spirulina platensis. This was achieved by utilizing a temperature-sensitive polymer, Pluronic F68, in an aqueous two-phase solvent system. The phase behavior of the temperature-sensitive polymer-based biphasic system was evaluated. The extraction conditions were optimized by both single-factor experiments and response surface methodology. Under the optimal conditions, the upper polymer-rich phase was recycled for sustainable phycocyanin extraction, resulting in a grade of 3.23 during the third extraction cycle. Pluronic F68 could be efficiently recovered and reused during the extraction process. The interaction mechanism between Pluronic F68 and phycocyanin was systematically studied using FT-IR and fluorescence analysis. This was further complemented by static and dynamic calculation of molecular motion through molecular docking and molecular dynamics simulation, indicating that hydrophobic segment of Pluronic F68 played a key role in the binding process with phycocyanin.

Significantly enhanced enzymatic hydrolysis of waste rice hull through a novel surfactant-based deep eutectic solvent pretreatment.

The potential of green solvents, specifically deep eutectic solvents (DESs), has piqued the interest of researchers in the field of lignocellulose pretreatment. To enhance the enzymatic digestion efficiency of waste rice hull (RCH), an effective pretreatment approach was developed using the DES [AA][CATB], which was made with acetic acid (AA) and cetyltrimethylammonium bromide (CTAB). The results showed that [AA][CATB] improved enzymatic saccharification by 3.7 times compared to raw RCH and efficiently eliminated lignin and removed xylan. The improvement in enzymatic hydrolysis efficiency was then interpreted by a series of characterizations that showed a great morphological changed RCH with an obvious accessibility increase and a lignin surface area and hydrophobicity reduction. This work demonstrates that functional, and easily recoverable DESs have potential for improving the efficiency of lignocellulose pretreatment in biorefineries, providing a promising approach for developing green solvents and achieving more sustainable and efficient biorefinery processes.

Molecular dynamics study on the encapsulation and release of anti-cancer drug doxorubicin by chitosan.

Doxorubicin (DOX) is a broad-spectrum anti-tumor drug, but it has certain limitations in its therapeutic effects due to poor tumor selectivity. Chitosan-based pH-sensitive polymers drug delivery systems could improve DOX's activity and selectivity against tumor cells. Understanding the atomic interaction mechanism between chitosan and DOX at different pH levels is important in the design and application of chitosan-based drug delivery systems. In this study, molecular dynamics simulations were performed to investigate the encapsulation and release of DOX by chitosan at different pH levels. Our results show that the protonation state of amine groups of chitosan and the π-π stacking interaction between the conjugated anthraquinone ring of DOX regulate the interaction behavior between chitosan and DOX. Moreover, DOX could gradually release from chitosan at acidic pH environment in tumor tissue. These results revealed the underlying atomic interaction mechanism between DOX and chitosan at various pH levels and may provide novel ideas for the design and application of chitosan-based drug delivery system.

Graphene quantum dot assisted translocation of drugs into a cell membrane.

Graphene quantum dots (GQDs) are increasingly being recognized as anti-cancer drug carriers, e.g., doxorubicin delivery, in many experiments. In this work, the structure, thermodynamics and dynamic properties of model drugs (doxorubicin and deoxyadenosine) translocating into a POPC lipid membrane with the assistance of GQDs were investigated via MD simulation and free energy calculation. The simulation results imply that GQD19 can facilitate the permeation of model drugs into the lipid membrane on the nanosecond timescale with less deformation of the cell membrane structure. More importantly, free energy calculations further revealed that the translocation free energy of doxorubicin or deoxyadenosine permeating into the lipid bilayer could be significantly reduced with the assistance of GQD19. Our results suggest that GQDs with appropriate size may assist in the drug delivery process by reducing the translocation free energy permeating into the biomembrane. These results may promote the molecular design and application of GQD-based drug delivery systems.

Shield effect of silicate on adsorption of proteins onto silicon-doped hydroxyapatite (100) surface.

Protein adsorption-desorption on nanoscale surface plays a key role in biomaterials, cell adhesion, biosensors, biofuel cells and biomineralization. Silicate-substituted hydroxyapatite (SiHA) is one of the most interesting bioceramics in the field of bioactive hard tissue implants. In this paper, the adsorption-desorption behaviors of leucine-rich amelogenin protein (LRAP) on a series of SiHA (100) surfaces were investigated using the molecular dynamics (MD), steered molecular dynamics (SMD) simulations and density functional theory (DFT) calculations. It was found that the silicate ions on SiHA (100) surface cause a shield effect, which was composed of the charge repulsion and the steric hindrance of silicates. These findings suggest that surface engineering technologies can be potentially used to directly control/manufacture the nanoscale surface texture and the composition of material surfaces, thereby to mediate the interaction of proteins with biomaterials.

Induced stepwise conformational change of human serum albumin on carbon nanotube surfaces.

Non-covalent adsorption of proteins onto carbon nanotubes is important to understand the environmental and biological activity of carbon nanotubes as well as their potential applications in nanostructure fabrication. In this study, the adsorption dynamics and features of a model protein (the A sub-domain of human serum albumin) onto the surfaces of carbon nanotubes with different diameters were investigated out by molecular dynamics simulation. The adsorption behaviors were observed by both trajectory and quantitative analyses. During the adsorption process, the secondary structures of alpha-helices in the model protein were slightly affected. However, the random coils connecting these alpha-helices were strongly affected and this made the tertiary structure of protein change. The conformation and orientation selection of the protein were induced by the properties and the texture of surfaces indicated by the interaction curve. In addition, the stepwise adsorption dynamics of these processes are found. The mechanism of induced stepwise conformational change of protein on carbon nanotube surfaces would be helpful to better understand the protein-surface interaction at the molecular level.

Diameter selectivity of protein encapsulation in carbon nanotubes.

Biomolecular-carbon nanotube (CNT) complexes are of great importance in biological and biomedical devices, and recently spontaneous encapsulation of biomolecules into CNTs has attracted great interest. In this work, we explored the diameter selectivity of the protein encapsulation in CNTs via molecular dynamics simulations, and the free energy changes of the systems were calculated for mechanism exploration. It is proved that there is an optimal tube size which provides the most effective encapsulation for a given protein molecule, and the encapsulations in the overlarge and overcrowded tubes are hindered by different factors based on the analysis of system energy contribution. In addition, the significance of the solvents for the system is also of concern.