Poly N-isopropylacrylamide Research Articles

Tillandsia-Inspired Ultra-Efficient Thermo-Responsive Hygroscopic Nanofibers for Solar-Driven Atmospheric Water Harvesting.

Sorption-based atmospheric water harvesting (SAWH) is a promising approach for supplying water in off-grid arid regions. However, it is difficult to improve the SAWH efficiency because water undergoes multiple phase transformations, such as water vapor-water (desorption and condensation) in the desorption phase. To address this issue, an ultrahygroscopic temperature-responsive hydrogel nanofiber inspired by Tillandsia is developed, comprising poly N-isopropylacrylamide, poly N-dimethylacetamide, and carbon nanotubes and impregnated with lithium chloride (PCP@LiCl). The hydrophobicity of the nanofiber membrane is enhanced with increasing temperature, facilitating water separation from the hydrogel in liquid form. Moreover, PCP@LiCl exhibits unique kinetics at 25 °C and 15%-30% relative humidity, capable of adsorbing moisture to saturation within 2h, and oozing liquid water within 5min under sunlight. Through global potential modeling, it is demonstrated that PCP@LiCl has potential applications in arid and semiarid regions. This study provides new insights into the design of high-performance composites for solar-powered atmospheric water harvesting.

A phosphate glass reinforced composite acrylamide gradient scaffold for osteochondral interface regeneration

The bone-cartilage interface is defined by a unique arrangement of cells and tissue matrix. Injury to the interface can contribute to the development of arthritic joint disease. Attempts to repair osteochondral damage through clinical trials have generated mixed outcomes. Tissue engineering offers the potential of integrated scaffold design with multiregional architecture to assist in tissue regeneration, such as the bone-cartilage interface. Challenges remain in joining distinct materials in a single scaffold mass while maintaining integrity and avoiding delamination. The aim of the current work is to examine the possibility of joining two closely related acrylamide derivatives such as, poly n-isopropyl acrylamide (pNIPAM) and poly n‑tert‑butyl acrylamide (pNTBAM). The target is to produce a single scaffold unit with distinct architectural regions in the favour of regenerating the osteochondral interface. Longitudinal phosphate glass fibres (PGFs) with the formula 50P2O5.30CaO.20Na2O were incorporated to provide additional bioactivity by degradation to release ions such as calcium and phosphate which are considered valuable to assist the mineralization process. Polymers were prepared via atom transfer radical polymerization (ATRP) and solutions cast to ensure the integration of polymers chains. Scaffold was characterized using scanning electron microscope (SEM) and Fourier transform infra-red (FTIR) techniques. The PGF mass degradation pattern was inspected using micro computed tomography (µCT). Biological assessment of primary human osteoblasts (hOBs) and primary human chondrocytes (hCHs) upon scaffolds was performed using alizarin red and colorimetric calcium assay for mineralization assessment; alcian blue staining and dimethyl-methylene blue (DMMB) assay for glycosaminoglycans (GAGs); immunostaining and enzyme-linked immunosorbent assay (ELISA) to detect functional proteins expression by cells such as collagen I, II, and annexin A2. FTIR analysis revealed an intact unit with gradual transformation from pNIPAM to pNTBAM. SEM images showed three distinct architectural regions with mean pore diameter of 54.5 µm (pNIPAM), 16.5 µm (pNTBAM) and 118 µm at the mixed interface. Osteogenic and mineralization potential by cells was observed upon the entire scaffold's regions. Chondrogenic activity was relevant on the pNTBAM side of the scaffold only with minimal evidence in the pNIPAM region. PGFs increased mineralization potential of both hOBs and hCHs, evidenced by elevated collagens I, X, and annexin A2 with reduction of collagen II in PGFs scaffolds. In conclusion, pNIPAM and pNTBAM integration created a multiregional scaffold with distinct architectural regions. Differential chondrogenic, osteogenic, and mineralized cell performance, in addition to the impact of PGF, suggests a potential role for phosphate glass-incorporated, acrylamide-derivative scaffolds in osteochondral interface regeneration.

Synthesis of Responsive Membranes for Water Recovery through Desalination of Saline Industrial Effluents

Polysulfone (PSF) and smart polymers (SRPs)—including polyacrylic acid (AAc), poly N-isopropylacrylamide (NIPA), and sulfonated poly(1,4-phenylene ether-ether-sulfone) (SPEES)—were used in the synthesis of responsive membranes (PSF-SRP) for application in sustainable desalination processes involving food industry effluents for water recovery and recycling. With the inclusion of SRPs, PSF-SRP membranes showed different characteristics when compared to the PSF membrane. AAc caused fibers to occur in the surface structure, increasing the MWCO of the PSF membrane, whereas NIPA and SPEES diminished the MWCO, resulting in ultrafiltration and nanofiltration membranes. Furthermore, NIPA and SPEES provided high mechanical and thermal resistance when incorporated into the PSF membrane. The performance of the membranes also showed important changes. In comparison with only PSF, PSF-SPEES and PSF-NIPA increased the water flux and salt rejection percentage by 20–30%. In addition, the highest membrane fouling resistance was observed with PSF-NIPA, while PSF-AAc and PSF-NIPA-AAc presented the lowest resistances. Therefore, PSF-NIPA and PSF-SPEES resulted in membrane improvement, including stimuli-responsive properties, allowing for effective saline effluent treatment.

When thermochromic material meets shape memory alloy: A new smart window integrating thermal storage, temperature regulation, and ventilation

Traditional windows have poor thermal insulation performance, resulting in significant indoor heat loss in winter and outdoor heat entry in summer. Thermochromic smart windows can effectively block solar radiant heat by automatically adjusting light transmittance, thereby reducing air conditioning loads and leading to significant energy savings. In this study, the poly N-isopropyl acrylamide (PNIPAm)-based thermochromic hydrogel, modified MXene nanoparticles, and NiTi shape memory alloy (SMA) are integrated to endow the smart window with heat storage, temperature control, and ventilation. The smart window achieves 88.6% visible light transmission and 70% solar modulation. The inclusion of MXene nanoparticles further enhances photothermal response efficiency, while the ventilation system ensures efficient and fresh indoor air circulation. Compared to the common glass, the smart window reduces the indoor temperature by 8 °C, demonstrating its excellent temperature regulation ability. Simulation results indicate that in Shanghai, Cairo, Singapore, and Kuwait, the employment of thermochromic smart windows can reduce heating, ventilation, and air conditioning energy consumption (HVAC) by 32.6%, 49.9%, 42.7%, and 34.1%, respectively. This versatile thermochromic smart window is expected to significantly improve building efficiency and occupant comfort, offering a sustainable solution for future building designs.

Water Confinement on Polymer Coatings Dictates Proton-Electron Transfer on Metal-Catalyzed Hydrogenation of Nitrite.

Enzymes can precisely control the speed and selectivity of chemical reactions by modifying locally the solvent-reactant interactions. To extrapolate these attributes to heterogeneous catalysts, we have employed thermoresponsive poly n-isopropylacrylamide (p-NIPAM) brushes bonded to silica spheres containing palladium. These polymers can form hydrogen bonds with water molecules at low temperatures (<32 °C) allowing the polymer to stay swollen. Detailed reaction kinetics of nitrite hydrogenation showed that p-NIPAM decreases the apparent activation barrier by a factor of 3 at low temperatures. Diffusion-ordered spectroscopy nuclear magnetic resonance and ab initio molecular dynamics simulations showed that when p-NIPAM is present, water molecules near the surface are less mobile. This confinement perturbs the water interaction with the metal, reducing the barrier for the proton-electron transfer reduction of nitrite. Notably, this enhancement vanishes at high temperature as the polymer collapses on itself exposing the Pd to unconfined water. The fully reversible nature of this process opens the door for creating homeostatic catalysts with controlled water-confinement.

Antibacterial and Osteogenic Doxycycline Imprinted Bioglass Microspheres to Combat Bone Infection.

Currently, postoperative infection is a significant challenge in bone and dental surgical procedures, demanding the exploration of innovative approaches due to the prevalence of antibiotic-resistant bacteria. This study aims to develop a strategy for controlled and smart antibiotic release while accelerating osteogenesis to expedite bone healing. In this regard, temperature-responsive doxycycline (DOX) imprinted bioglass microspheres (BGMs) were synthesized. Following the formation of chitosan-modified BGMs, poly N-isopropylacrylamide (pNIPAm) was used for surface imprinting of DOX. The temperature-responsive molecularly imprinted polymers (MIPs) exhibited pH and temperature dual-responsive adsorption and controlled-release properties for DOX. The temperature-responsive MIP was optimized by investigating the molar ratio of N,N'-methylene bis(acrylamide) (MBA, the cross-linker) to NIPAm. Our results demonstrated that the MIPs showed superior adsorption capacity (96.85 mg/g at 35 °C, pH = 7) than nonimprinted polymers (NIPs) and manifested a favorable selectivity toward DOX. The adsorption behavior of DOX on the MIPs fit well with the Langmuir model and the pseudo-second-order kinetic model. Drug release studies demonstrated a controlled release of DOX due to imprinted cavities, which were fitted with the Korsmeyer-Peppas kinetic model. DOX-imprinted BGMs also revealed comparable antibacterial effects against Staphylococcus aureus and Escherichia coli to the DOX (control). In addition, MIPs promoted viability and osteogenic differentiation of MG63 osteoblast-like cells. Overall, the findings demonstrate the significant potential of DOX-imprinted BGMs for use in bone defects. Nonetheless, further in vitro investigations and subsequent in vivo experiments are warranted to advance this research.

Thermally and magnetically responsive single layer bioinspired soft actuator with patterned structure obtained by direct ink writing

Multi-stimuli hydrogels are an important class of soft actuators, as they allow to expand the range of possible movements and responses by more closely mimicking living matter. Here we report the fabrication of thermally- and magnetically-responsive single layer hydrogel nanocomposite obtained by direct ink writing. Two types of inks, namely, thermosensitive based on poly(N-isopropylacrylamide) (PNIPAM), and magnetically-sensitive based on magnetite particles, were distributed according to a certain pattern, forming a single-layer hydrogel sheet. Thermally-responsive inks due to “coil-to-globule” transformation of PNIPAM at temperatures above 32°C in aqueous solutions generate local internal stresses which lead to the transformation of the hydrogel’s shape. Magnetically sensitive ink allows to move the hydrogel in the space by attracting it to a magnet. Inks' formulations have been optimized to achieve thixotropic properties for the application of direct ink writing. The proposed hydrogel system represents a powerful platform for the development of biomedical soft robots because it consists of biocompatible components and operates in a temperature range close to the human body.

The Influence of Initiators, Particle Size and Composition on the Electrokinetic Potential of N-(Isopropyl)acrylamide Derivatives.

The aim of this study was to characterize and compare the zeta potential of particles sensitive to external thermal stimuli. Poly N-(isopropyl) acrylamide (PNIPA) was selected as the thermosensitive polymer with a volume phase transition temperature (VPTT) between 32 and 33 °C. The hydrodynamic diameter (DH) of the nanoparticles was measured by dynamic light scattering. Zeta potential (ZP) measurements were performed with the same instrument used for DH measurements. ZP measurements allow the prediction of the stability of colloidal systems in aqueous solutions. These measurements were combined with a pH study before and after the purification process of the particles. The ZP was measured to determine the electrostatic interactions between the particles, which can lead to particle aggregation and decrease their colloidal stability. The effect of the composition of the synthesized particles on the ZP was assessed. One of the most important factors influencing ZP is pH, especially in aqueous solutions. The initiator did not significantly affect the DH of the particles, but it did significantly affect the ZP. The synthesized particles were subjected to a visible radiation absorption study in the selected temperature range to determine the VPTT.

Regenerated silk fibroin coating stable liquid metal nanoparticles enhance photothermal antimicrobial activity of hydrogel for wound infection repair

The integration of liquid metal (LM) and regenerated silk fibroin (RSF) hydrogel holds great potential for achieving effective antibacterial wound treatment through the LM photothermal effect. However, the challenge of LM's uncontrollable shape-deformability hinders its stable application. To address this, we propose a straightforward and environmentally-friendly ice-bath ultrasonic treatment method to fabricate stable RSF-coated eutectic gallium indium (EGaIn) nanoparticles (RSF@EGaIn NPs). Additionally, a double-crosslinked hydrogel (RSF-P-EGaIn) is prepared by incorporating poly N-isopropyl acrylamide (PNIPAAm) and RSF@EGaIn NPs, leading to improved mechanical properties and temperature sensitivity. Our findings reveal that RSF@EGaIn NPs exhibit excellent stability, and the use of near-infrared (NIR) irradiation enhances the antibacterial behavior of RSF-P-EGaIn hydrogel in vivo. In fact, in vivo testing demonstrates that wounds treated with RSF-P-EGaIn hydrogel under NIR irradiation completely healed within 14 days post-trauma infection, with the formation of new skin and hair. Histological examination further indicates that RSF-P-EGaIn hydrogel promoted epithelialization and well-organized collagen deposition in the dermis. These promising results lay a solid foundation for the future development of drug release systems based on photothermal-responsive hydrogels utilizing RSF-P-EGaIn.

Solution critical temperature through Excess-entropy-Diffusivity lens

Poly-N-isopropyl acrylamide (PNIPAM) is a widely studied thermo-responsive polymer with unique properties and numerous applications, including cell engineering and protein attachment. However, quantifying the responsive behavior of such polymers is challenging due to the vast configurational space. Existing methods for quantification are either focused on dynamic properties or structural properties, but the changes in structural parameters are small, while those in dynamic properties are significantly larger. This study proposes a new computational method considering non-equilibrium-activity-driven segregation to quantify responsive behaviors using structure (excess entropy) and dynamic (diffusivity) properties. We have calculated the Lower Critical Solution Temperature (LCST) for the N-Isopropyl propionamide (NIPPAm) -water system for different solute fractions by scaling excess entropy with diffusivity obtained by performing all-atom Molecular Dynamics simulations. Our method can precisely reproduce the LCST temperature in the 0.17–0.25 mol fraction concentration range. This approach can be used to study the responsive behavior of other polymers at different stimuli and improve our understanding of their applications.

A DNA-polymer hybrid nanocomplex based bi-adjuvant vaccine for tumor immunotherapy

The immunosuppressive tumor microenvironment (TME) seriously impedes the cancer immunotherapy; Toll-like receptors (TLRs) agonists combination is emerging as vaccine adjuvant in reprogramming tumor immune microenvironment. Herein, we develop a supramolecular DNA-polymer hybrid nanocomplex-based bi-adjuvant vaccine for tumor immunotherapy. In the nanocomplex, the co-assembly of TLR9 agonist (CpG) and TLR7 agonist (loxoribine) was achieved via dynamic DNA assembly and boron chemistry. Poly-N-isopropyl acrylamide (PNIPAM) served as the framework of the nanocomplex, and meanwhile, designer DNA sequences were introduced as cross-linkers in the nanoframework to trigger the hybridization chain reaction (HCR)-based assembly of CpG sequences containing hairpins. The polymer framework was decorated with phenylboronic acid to capture and release loxoribine via reversible formation of cyclic boric acid ester. A lipid shell was coated on the outside of the CpG and loxoribine co-loaded nanocomplex to prevent the leakage of loxoribine in plasma. After intravenous injection, the nanocomplex was internalized by the tumor-associated immune cells via lysosomal related pathways. CpG and loxoribine synergistically stimulated TLR9 and TLR7 receptors, thus leading to the conversion of suppressive M2 macrophage to active M1 macrophage, maturation of dendritic cells, and activation of T cells. The dual activation of TLR9 and TLR7 effectively reprogramed tumor immune microenvironments in vivo, wherein robust CD8+ T cell response and efficient tumor regression were achieved. This work provides a unique design concept for the TLR agonists combination-based nanovaccine for tumor immunotherapy.

Construction of a Dual-Mode Immune Platform Based on the Photothermal Effect of AgCo@NC NPs for the Detection of α-Fetoprotein.

Compared with the accuracy of a single signal and the limitation of environmental applicability, the application value of dual-mode detection is gradually increasing. To this end, based on the photothermal effect of Ag/Co embedded N-rich mesoporous carbon nanomaterials (AgCo@NC NPs), we designed a dual-mode signal response system for the detection of α-fetoprotein (AFP). First, AgCo@NC NPs act as a photothermal immunoprobe that converts light energy into heat driven by a near-infrared (NIR) laser and obtains temperature changes corresponding to the analyte concentration on a hand-held thermal imager. In addition, this temperature recognition system can significantly improve the efficiency of Fenton-like reactions. AgCo@NC NPs act as peroxidase mimics to initiate the generation of poly N-isopropylacrylamide (PNIPAM, resistance enhancer) by cascade catalysis and the degradation of methylene blue (MB), thus enabling electrochemical testing. The dual-mode assay ranges from 0.01 to 100 and 0.001-10 ng/mL, with lower limits of detection (LOD) of 3.2 and 0.089 pg/mL, respectively, and combines visualization, portability, and high efficiency, opening new avenues for future clinical diagnostics and inhibitor studies.

Multifunctional hollow silica carriers with spiny structure for enhanced foliar adhesion and triple-responsive pesticide delivery

Intelligent responsive pesticide formulations hold great promise for enhancing foliage retention and effective utilization. Herein, hollow silica (S-HS) nanocarriers with spiny structure were constructed for pesticide delivery. The S-HS nanocarriers presented homogeneous spiny spheres with an average size of 220 nm. This spiny structure can achieve effective retention on foliage by the “hanger-hat” topology effect. For constructing the responsive layer, the S-HS nanocarriers were further functionalized with surface vinyl groups. After loading imidacloprid (IMI), the temperature sensitive poly N-isopropylacrylamide (pNIPAm) and tannic acid–Fe complexes (TA-Fe) were introduced to encapsulate pesticides (IMI@S-HS-pNT). The TA-Fe complex layer served as a wall material and photothermal agent. The S-HS-pNT carriers achieved a loading capacity for IMI (26.6 %), high photothermal conversion effect (η = 36.1 %), and good biocompatibility. Except for excellent photostability and foliar adhesion property, the IMI@S-HS-pNT exhibited pH, temperature and near infrared (NIR) responsive release behavior. Moreover, the S-HS nanocarriers could be effectively transported to various parts of tobacco plants under the root immerse or foliar spray. The IMI@S-HS-pNT showed the high control efficacy against Plutella xylostella. Overall, this work provides insight into improving the efficiency of utilization and prolonging pesticide retention on plant leaves.

Modifying reaction rates and stimulus-responsive behavior of polymer-coated catalysts using aprotic solvents

The impact of solvent composition on the reaction rates and apparent activation barriers for the reduction of nitrobenzene on Pd has been investigated by changing the solvent from pure water to mixtures with increasing concentrations of 1-methyl-2-pyrrolidone (NMP). When using pure NMP as the solvent, the activity was negligible and a high activation energy barrier was observed. Surprisingly, switching to water led to faster reaction rates and lower apparent barriers. Considering that previous research has demonstrated that water molecules near the catalyst surface facilitate the hydrogen insertion on R-NO* and R-HNO* surface species via proton-electron transfer, it is possible to link the herein observed trends in activity for the nitrobenzene hydrogenation to the ability of the reaction media to shuttle protons during the reaction. Furthermore, the polymer-induced solvation effects were investigated using thermo-responsive Pd/SiO2-p-NIPAM catalyst. Here, we observed that the utilization of NMP inhibits the thermo-responsive behaviour of poly N-isopropylacrylamide (p-NIPAM). This explains the constant particle size of Pd/SiO2-p-NIPAM catalyst observed at different temperatures during dynamic light scatting characterization (DLS). We speculate that this non-responsive behaviour of the p-NIPAM in the presence of NMP is the cause of the constant activation energy barrier at temperatures above and below the lower critical solution temperature (LCST) of the polymer (32 °C). When the reaction was conducted in pure water, the polymer-coated catalyst showed significant changes in both the apparent enthalpy and entropy of activation for temperatures below and above the LCST. This suggests that the microenvironment induced by the polymer can significantly influence the reaction rate.

Hydrogel Micropillar Array for Temperature Sensing in Fluid.

Localized temperature sensing and control on a micron-scale have diverse applications in biological systems. We present a micron-sized hydrogel pillar array as potential temperature probes and actuators by exploiting sensitive temperature dependence of their volume change. Soft lithography-based molding processes were presented to fabricate poly N-isopropyl acrylamide (p-NIPAAm)-based hydrogel pillar array on a glass substrate. Au nanorods as light-induced heating elements were embedded within the hydrogel pillars, and near-infrared (NIR) light was used to modulate temperature in a local area. First, static responses of the micro-pillar array were characterized as a function of its temperature. It was shown that the hydrogel had a sensitive volume transition near its low critical solution temperature (LCST). Furthermore, we showed that LCST could be readily adjusted by utilizing copolymerizing with acrylamide (AAM). To demonstrate the feasibility of spatiotemporal temperature mapping and modulation using the presented pillar array, pulsed NIR light was illuminated on a local area of the hydrogel pillar array, and its responses were recorded. Dynamic temperature change in water was mapped based on the abrupt volume change characteristics of the hydrogel pillar, and its potential actuation using NIR light was successfully demonstrated. Considering that the structure can be arrayed in a two-dimensional pixel format with high spatial resolution and high sensitive temperature characteristics, the presented method and the device structure can have diverse applications to change and sense local temperatures in liquid. This is particularly useful in biological systems, where their physiological temperature can be modulated and mapped with high spatial resolution.

The advanced polymer composite coated fabrics as an anode electrode and photocatalytic glucose micro fuel cell design

At present, poly N-isopropyl acrylamide (PNIPAM) polymer composites containing titanium dioxide (TiO2) and carbon-TiO2 (C-TiO2) were designed for photocatalytic glucose electrooxidation by coating the textile fabric surface such as wool blended fabrics called Sign Cocana (SC), Valencia (VC), Dante (DT), and Broadway (BW). C-TiO2 was obtained from TiO2 in a furnace under hexane gas with a certain temperature and time. Polymer synthesis was realized by a polymerization method. The surface analyses of these polymer composite fabric electrodes were characterized by scanning electron microscopy-energy dispersive X-Ray (SEM-EDX) and mapping analysis. In addition, tear and breaking strengths were examined. Photocatalytic activity of the polymer composite electrodes was examined by cyclic voltammetry (CV). The C-TiO2-graft(g)-PNIPAM/SC electrode exhibited the best photocatalytic activity under UV illumination with a specific activity of 2.80 mA/cm2 both in the dark and compared to other fabric electrodes. In addition, it was observed that it exhibited the best stability and resistance by chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) analyses. It could be a promising anode electrode for photocatalytic fuel cells and wearable electronics.

Selective in situ dynamic motion stay and recover under single NIR light in soft actuator by triggered Shape-Memory and phase transition of hydrogel

Inspired by nature, hydrogel actuators are important for designing soft robots and become one of the most essential components of intelligent research. However, classical actuation method, such as Near-Infrared (NIR) light stimulates the actuator to complete the motions then it automatically recovers original state when the light is off, cannot provide continuous in situ dynamic motion stay and recovery under one NIR light. In this study, a novel network-polycaprolactone (Net-PCL)-poly N-isopropylacrylamide (PNIPAM) hydrogel actuator (Net-PCL-Gel) is proposed through a layer-by-layer stacking technology, leading to the co-existence of Net-PCL with photoinduced shape memory capability and PNIPAM hydrogel segments showing de-swelling/swelling phase transition. Owing to the shape memory property of Net-PCL, the Net-PCL-Gel exhibits in situ dynamic bending and recovering stay behavior in response to NIR irradiation with the active force of PNIPAM. Different from the conventional hydrogel system, the Net-PCL-Gel also displayed remarkable decryption performance in information reading and hiding, while retaining excellent accuracy and stability. Due to its simplicity, this strategy shows great potential for the biomimetic operation of soft grippers and multifunctional actuators.

Synthesis, Thermogravimetric Analysis, and Kinetic Study of Poly-N-Isopropylacrylamide with Varied Initiator Content.

The thermal decomposition and kinetic parameters of four polymers, PN-1, PN-05, PN-01, and PN-005, were determined by thermogravimetry (TGA/DTG) under non-isothermal conditions. N-isopropylacrylamide (NIPA)-based polymers were synthesized by the surfactant-free precipitation polymerization (SFPP) with different concentrations of the anionic initiator potassium persulphate (KPS). Thermogravimetric experiments were carried out in the temperature range of 25-700 °C at four heating rates, 5, 10, 15, and 20 °C min-1, under a nitrogen atmosphere. Poly NIPA (PNIPA) showed three stages of mass loss during the degradation process. The thermal stability of the test material was determined. Activation energy values were estimated using Ozawa, Kissinger, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman (FD) methods.

Synthesis and Characterization of Gelatin/Poly N-Isopropylacryl Amide Nanocomposite Hydrogels by Response Surface Methodology

In this study, after producing Poly N-isopropylacryl amide (PNIPAAm) nanoparticles by a novel method including a combination of the UV photopolymerization technique and the liposomal nanoreactors approach, which resulted in homogenous, nanosized PNIPAAm nanoparticles, gelatin/PNIPAAm hydrogels were prepared. An investigation of the effect of monomer, crosslinking agent, and nanoparticle concentrations to gelatin weight percent on the morphology, size, structure, phase transition temperature, swelling, and biodegradability of the nanocomposite hydrogels were carried out. The response surface method (RSM) was used to develop models for predicting and optimizing the hydrogels. Fourier-transform infrared spectroscopy (FTIR) spectra of the monomer, polymers, and nanocomposites indicated the incorporation of the poly N-isopropylacrylamid (PNIPAAm) nanoparticles and gelatin in the structure. Based on scanning electron microscope (SEM) images and dynamic light scattering (DLS) results, the size of the nanoparticles was 250–300 nm which were dispersed well in the gelatin hydrogel. In addition, the nanocomposites showed 80–110% swelling in water, a phase transition temperature (LCST) around 32.5 °C and a biodegradation capability under physiological conditions.

Multifunctional thermosensitive hydrogel based on alginate and P(NIPAM-co-HEMIN) composites for accelerated diabetic wound healing

Non-healing wounds in patients with diabetes are a concerning issue associated with amputation and a high mortality rate. These wounds are exacerbated by oxidative stress and microbial infections resulting from hyperglycemia. Therefore, advanced materials for repairing wound beds must be identified urgently. This paper introduces a topically applicable composite hydrogel with thermosensitive properties and presents the antibacterial and antioxidant activities in mice with diabetes-induced wounds. This composite is developed by combining poly N-isopropyl acrylamide (NIPAM)-copolymerized HEMIN (NIPAM-co-HEMIN) and amine-modified alginate (ALG-EDA) biomaterials, with Ag nanoparticles (AgNPs) incorporated into the system as an antibacterial agent. Results of antibacterial tests show that the p(NIPAM-co-HEMIN)/ALG-EDA/AgNP composite system is effective against E. coli and S. aureus. Additionally, the AgNP composite exhibits low cellular toxicity in NIH3T3 and CT-2A cell lines. The wounds in diabetic mice treated with the composite system healed in <12 days, and the composite system accelerated the healing process by increasing collagen synthesis. In conclusion, the biocomposite reported herein is highly promising for repairing diabetic skin wounds and treating infections caused by bacterial microbes.