Fabrication of novel dual thermo- and pH-sensitive poly (N-isopropylacrylamide-N-methylolacrylamide-acrylic acid) electrospun ultrafine fibres for controlled drug release

Enhanced wound healing with a bilayered multifunctional quaternized chitosan-dextran-curcumin construct

This study introduces a novel bilayer wound dressing that integrates a quaternized chitosan-polyacrylic acid (QCs-PAA) sponge as the top layer with electrospun nanofibers containing curcumin as the bottom layer. For the first time, QCs and PAA were combined in an 80:20 ratio through freeze-drying to form a porous sponge layer with ideal structural properties, including 83 ± 6 % porosity and pore diameters of 290 ± 12.5 μm. For the bottom layer, five groups of nanofibers containing PAA, dextran, and curcumin were electrospun onto the porous sponge. All wound dressings were non-toxic and exhibited exceptional antibacterial activity against S. aureus and E. coli. All groups, particularly the QP/PD0.25Cur bilayer dressing, showed significant HaCaT cell adhesion. Angiogenesis assays confirmed a remarkable increase in blood vessel number and thickness in samples containing 0.25 w/w% curcumin, with vascular density increasing from 0.32 in the single-layer sponge to 0.54 in the QP/PD0.25Cur sample, representing a 68 % enhancement. In vivo studies demonstrated that within 14 days, wound healing was accelerated with the QP/PD0.25Cur bilayer dressing, achieving 96 % closure compared to other groups. The findings revealed that all fabricated bilayer sponge-nanofiber wound dressings, particularly the 0.25 w/w% curcumin sample, can be a suitable candidate for wound management.

Engineering Multiresponsive Alginate/PNIPAM/Carbon Nanotube Nanocomposite Hydrogels as On-Demand Drug Delivery Platforms

Second near-infrared (NIR-II) responsive hydrogels have shown significant potential in biomedical applications due to their excellent remote actuation property and the high tissue penetrations of the NIR-II light. Nevertheless, hydrogels with a single NIR-II light response may not meet the diverse requirements and complex conditions of clinical applications. Here, a novel multi-responsive nanocomposite hydrogel with enhanced suitability for controlled drug release is developed. This nanocomposite hydrogel is constructed by combining alginate dialdehyde (ADA), polyethyleneimine (PEI), poly(N-isopropylacrylamide) (PNIPAM), and phenylboronic acid-modified polyethyleneimine (PBA-PEI) functionalized multi-walled carbon nanotubes (PP-CNT) through the formation of dynamic covalent bonds (i.e., imine bonds and boronate ester bonds), forming ADA/PEI/PNIPAM/PP-CNT (APN/PP-CNT) hydrogel. PNIPAM is incorporated into the hydrogel network to facilitate drug release triggered by its aggregation when subjected to the high temperatures produced by NIR-II light irradiation. The dynamic covalent bonds and CNT in the network provide the APN/PP-CNT nanocomposite hydrogels with responsiveness to multiple stimuli, including pH, hydrogen peroxide, temperature, and NIR-II light. The APN/PP-CNT nanocomposite hydrogel performs effective NIR-II light responsiveness in both in vitro and in vivo drug release, highlighting its potential as a promising drug delivery platform.

Octopus-inspired flocculant for oily wastewater decontamination: Hydrophilic-hydrophobic convertibility and auto-separation characters

Unilateral hydrophobic flocculant and unsatisfactory floc separation constrained the efficacious purification of oil-containing wastewater. Illumined by the hunting behavior of mimic octopus, a biomimetic flocculant (CNSDA) with temperature-sensitive chains (color pouch) and hollow silica cores (mantle) was manufactured to derive hydrophilic-hydrophobic convertibility and auto-separation capabilities. Physical-chemical information of CNSDA was elucidated through characterization analysis. The flocculation behaviors of temperature-sensitive chains and hollow silica cores were evaluated by flocculation experiments. Results indicated that the configuration of CNSDA molecular chains varied from extension to constriction and revealed hydrophobicity as the temperature crossed 29.6 ℃. Compared with 20 ℃, the flocculation efficiencies rocketed at 40 ℃ by CNSDA, and excess flocculants were adsorbed by as-formed flocs through nonpolar interactions (the residual was low to 2.27 % at 160 mg/L). Concomitantly, the contracted molecular chains were contributed to generating dense flocs with low moisture content that flocked into large ones and expedited the solid-liquid separation process (60 % shorter than cationic polyacrylamide) with the auxiliary of low-density cores. The hydrophobic adsorption mechanism actuated by temperature-sensitive character was the decisive factor for high-efficiency flocculation. This study can provide meaningful references for the conception and exploitation of oily wastewater disposal agents.

Molecular understanding of the self-assembly of an N-isopropylacrylamide delivery system for the loading and temperature-dependent release of curcumin

Global changes and drug abuse are forcing humanity to face various disease problems, and alternative therapies with safe natural substances have important research value. This paper combines various techniques in quantum chemical calculations and molecular simulations to provide molecular-level insight into the dynamics of the self-assembly of N-isopropylacrylamide (NIPAM) for loading curcumin (CUR). The results indicate that increasing the chain length of NIPAM molecules reduces their efficiency in encapsulating and locking CUR, and electrostatic interactions and van der Waals interactions are the main driving forces behind the evolution of system configurations in these processes. The isopropyl groups of NIPAM and the two phenolic ring planes of CUR are the main contact areas for the interaction between the two types of molecules. The thermosensitive effect of NIPAM can alter the distribution of isopropyl groups in NIPAM molecules around CUR. As a result, when the temperature rises from ambient temperature (300 K) to human characteristic temperature (310 K), the NIPAM-CUR interactions and radial distribution functions suggest that body temperature is more suitable for drug release. Our findings offer a vital theoretical foundation and practical guidance for researchers to develop temperature-sensitive drug delivery systems tailored for CUR, addressing its clinical application bottleneck.

Stimuli-responsive electrospun nanofibers for drug delivery, cancer therapy, wound dressing, and tissue engineering

The stimuli-responsive nanofibers prepared by electrospinning have become an ideal stimuli-responsive material due to their large specific surface area and porosity, which can respond extremely quickly to external environmental incitement. As an intelligent drug delivery platform, stimuli-responsive nanofibers can efficiently load drugs and then be stimulated by specific conditions (light, temperature, magnetic field, ultrasound, pH or ROS, etc.) to achieve slow, on-demand or targeted release, showing great potential in areas such as drug delivery, tumor therapy, wound dressing, and tissue engineering. Therefore, this paper reviews the recent trends of stimuli-responsive electrospun nanofibers as intelligent drug delivery platforms in the field of biomedicine.

The Formulation of Curcumin: 2-Hydroxypropyl-β-cyclodextrin Complex with Smart Hydrogel for Prolonged Release of Curcumin

Curcumin comes from the plant species Curcuma longa and shows numerous pharmacological activities. There are numerous curcumin formulations with gels or cyclodextrins in order to increase its solubility and bioavailability. This paper presents the formulation of complex of curcumin with 2-hydroxypropyl-β-cyclodextrin in a thermosensitive hydrogel, based on N-isopropylmethacrylamide and N-isopropylacrylamide with ethylene glycol dimethacrylate as a crosslinker. The product was characterized by chemical methods and also by FTIR, HPLC, DSC, SEM, XRD. The results show that synthesis was successfully done. With an increase in the quantity of crosslinker in the hydrogels, the starting release and the release rate of curcumin from the formulation of the complex with hydrogels decreases. The release rate of curcumin from the gel complex formulation is constant over time. It is possible to design a formulation that will release curcumin for more than 60 days. In order to determine the mechanism and kinetics of curcumin release, various mathematical models were applied by using the DDSolver package for Microsoft Excel application. The Korsmeyer-Peppas model best describes the release of curcumin from the gel formulation of the complex, while the values for the diffusion exponent (0.063-0.074) shows that mechanism of the release rate is based on diffusion.

Thermo-active Smart Electrospun Nanofibers

The recent burst of research on smart materials is a clear evidence of the growing interest of the scientific community, industry, and society in the field. The exploitation of the great potential of stimuli-responsive materials for sensing, actuation, logic, and control applications is favored and supported by new manufacturing technologies, such as electrospinning, that allows to endow smart materials with micro- and nano-structuration, thus opening up additional and unprecedented prospects. In this wide and lively scenario, this article systematically reviews the current advances in the development of thermo-active electrospun fibers and textiles, sorting them, according to their response to the thermal stimulus. Hence, several platforms including thermo-responsive systems, shape memory polymers, thermo-optically responsive systems, phase change materials, thermoelectric materials, and pyroelectric materials, have been described and critically discussed. The difference in active species and outputs of the aforementioned categories has been highlighted, evidencing the transversal nature of temperature stimulus. Moreover, the potential of novel thermo-active materials has been pointed out, revealing how their development could take to utmost interesting achievements. This article is protected by copyright. All rights reserved.

Superparamagnetic electrospun microrods for magnetically-guided pulmonary drug delivery with magnetic heating

Controlled pulmonary drug delivery systems employing non-spherical particles as drug carriers attract considerable attention nowadays. Such anisotropic morphologies may travel deeper into the lung airways, thus enabling the efficient accumulation of therapeutic compounds at the point of interest and subsequently their sustained release. This study focuses on the fabrication of electrospun superparamagnetic polymer-based biodegradable microrods consisting of poly(l-lactide) (PLLA), polyethylene oxide (PEO) and oleic acid-coated magnetite nanoparticles (OA·Fe₃O₄). The production of magnetite-free (0% wt. OA·Fe₃O₄) and magnetite-loaded (50% and 70% wt. Fe₃O₄) microrods was realized upon subjecting the as-prepared electrospun fibers to UV irradiation, followed by sonication. Moreover, drug-loaded microrods were fabricated incorporating methyl 4-hydroxybenzoate (MHB) as a model pharmaceutical compound and the drug release profile from both, the drug-loaded membranes and the corresponding microrods was investigated in aqueous media. In addition, the magnetic properties of the produced materials were exploited for remote induction of hyperthermia under AC magnetic field, while the possibility to reduce transport losses and enhance the targeted delivery to lower airways by manipulation of the airborne microrods by DC magnetic field was also demonstrated.