Search Results (393)

Background/Objectives. Efficient nucleic acid delivery into target cells remains a critical challenge in gene therapy. Due to its advantages in biocompatibility and safety, recent research has increasingly focused on non-viral gene delivery. Methods. A series of copolymers—synthesized by integrating thermally sensitive poly(N-isopropylacrylamide) (PNIPAm), hydrophilic poly(ethylene glycol) (PEG) grafts, and a polycationic poly(L-lysine) (PLL) block of varying lengths ((PNIPAm)₇₇-graft-(PEG)₉-block-(PLL)_z, z = 10–65)—were investigated. Plasmid DNA complexation with the copolymers was achieved through temperature-modulated methods. The resulting polyplexes were characterized by evaluating complex strength, particle size, zeta potential, plasmid DNA loading capacity, resistance to anionic stress, stability in serum, and lysosomal membrane destabilization assay. The copolymers’ potential for plasmid DNA delivery was assessed through cytotoxicity and transfection studies in cancer cell lines. Results. Across all complexation methods, the copolymers effectively condensed plasmid DNA into stable polyplexes. Particle sizes (60–90 nm) ranged with no apparent correlation to copolymer type, complexation method, or N/P ratio, whereas zeta potentials (+10–+20 mV) and resistance to polyanionic stress were dependent on the PLL length and N/P ratio. Cytotoxicity analysis revealed a direct correlation between PLL chain length and cell viability, with all copolymers demonstrating minimal cytotoxicity at concentrations required for efficient transfection. PNL-20 ((PNIPAm)₇₇-graft-(PEG)₉-block-(PLL)₂₀) exhibited the highest transfection efficiency among the tested formulations while maintaining low cytotoxicity. Conclusions. The study highlights the promising potential of (PNIPAm)₇₇-graft-(PEG)₉-block-(PLL)_z copolymers for effective plasmid DNA delivery to cancer cells. It reveals the importance of attaining the right balance between polyplex tightness and plasmid release to achieve improved biocompatibility and transfection efficiency. Full article

Curcumin is widely recognized for its various pharmacological properties, including antioxidant, anti-inflammatory, and anti-tumor activities. Nevertheless, the development of curcumin as a therapeutic agent is impeded by its limited oral bioavailability, which stems from its chemical instability, poor aqueous solubility, and rapid degradation. This study aimed to develop granule formulations incorporating poly(N-isopropylacrylamide)-grafted hyaluronic acid or HA-g-pNIPAM to enhance dissolution and protect curcumin from degradation. Three formulations were developed: F10 (HA-g-pNIPAM physically mixed with curcumin), F10 Encap (curcumin encapsulated within HA-g-pNIPAM), and F11 (curcumin granules without HA-g-pNIPAM). The stability results showed that F10 Encap effectively maintained curcumin content throughout the study period, retaining approximately 94% of its initial concentration by day 30, compared to 70% from F11 (p < 0.05) at 30 °C and 75% relative humidity. All dried curcumin granules exhibited excellent flowability, as determined by the angle of repose measurements. All three formulations exhibited a consistent particle size distribution across replicates, with a peak in the 150–180 μm size range. The sustained release observed for F10 Encap and F10 after the initial burst suggested that the HA-g-pNIPAM provided a controlled release mechanism, ensuring continuous curcumin dissolution over 240 min in gastric and intestinal conditions. These findings suggested that HA-g-pNIPAM improved dissolution and stability of curcumin. Full article

Osteoarthritis and metastatic bone cancers create pathological oxidative environments characterized by elevated reactive oxygen species (ROS). ROS impair bone regeneration by degrading the scaffold and suppressing mineralization. To address these challenges, we fabricated thermoresponsive scaffolds based on poly(N-isopropylacrylamide) (PNIPAAm) incorporating in situ-grown nanohydroxyapatite on graphene oxide nanoscrolls (nHA-GONS) using stereolithography (SLA). Three scaffold formulations were studied: pure PNIPAAm (PNP), PNIPAAm with 5 wt.% nHA-GONS (P5G), and PNIPAAm with 5 wt.% nHA-GONS reinforced with polycaprolactone (PCL) microspheres (PN5GP). Each scaffold was evaluated for (i) swelling and lower critical solution temperature (LCST) using differential scanning calorimetry (DSC); (ii) oxidative degradation assessed using Fourier-transform infrared spectroscopy (FTIR), mass loss, and antioxidant assays; and (iii) mineralization and morphology via immersion in simulated body fluid followed by microscopy. The PN5GP and P5G scaffolds demonstrated reversible swelling, sustained antioxidant activity, and enhanced calcium deposition, which enable redox stability and mineralization under oxidative environments, critical for scaffold functionality in bone repair. PNP scaffolds exhibited copper accumulation, while PN5GP suffered from accelerated mass loss driven by the PCL phase. These findings identify the P5G formulation as a promising scaffold. This study introduces a quantitative framework that enables the predictive design of oxidation-resilient scaffolds. Full article

Carbon dots (CDs), a class of carbon-based fluorescent nanomaterials, have garnered significant attention due to their tunable optical properties and functional versatility. In this study, we developed a hybrid material by grafting pH- and temperature-responsive copolymers onto CDs via reversible addition-fragmentation chain-transfer (RAFT) polymerization. Triamino-tetraphenylethylene (ATPE) and N-isopropylacrylamide (NIPAM) were copolymerized at varying ratios and covalently linked to CDs, forming a dual-responsive system. Structural characterization using FTIR, ¹H NMR, and TEM confirmed the successful grafting of the copolymers onto CDs. The hybrid material exhibited pH-dependent fluorescence changes in acidic aqueous solutions, with emission shifting from 450 nm (attributed to CDs) to 500 nm (aggregation-induced emission, AIE, from ATPE) above a critical pH threshold. Solid films of the hybrid material demonstrated reversible fluorescence quenching under HCl vapor and recovery/enhancement under NH₃ vapor, showing excellent fatigue resistance over multiple cycles. Temperature responsiveness was attributed to the thermosensitive poly(NIPAM) segments, with fluorescence intensity increasing above 35 °C due to polymer chain collapse and ATPE aggregation. This work provides a strategy for designing multifunctional hybrid materials with potential applications in recyclable optical pH/temperature sensors. Full article

It is widely recognized that fine surface structures found in nature contribute to surface functionality, and studies on the design of functional materials based on biomimetics have been actively conducted. In this study, polymer thin films with hierarchically ordered surface structure were prepared by combining both nanoimprinting using anodically oxidized porous alumina (AAO) as a template and surface-initiated atom transfer radical polymerization (SI-ATRP). To prepare such polymer films, we designed a new copolymer (poly{[2-(4-methyl-2-oxo-2H-chromen-7-yloxy)ethyl methacrylate]-co-[2-(2-bromo-2-methylpropionyloxy)ethyl methacrylate]}; poly(MCMA-co-HEMABr)) with coumarin moieties and α-haloester moieties in the pendants. The MCMA repeating units function to fix the pillar structure by photodimerization, and the HEMABr ones act as the polymerization initiation sites for SI-ATRP on the pillar surfaces. Surface structures consisting of vertically oriented multiple pillars were fabricated on the spin-coated poly(MCMA-co-HEMABr) thin films by nanoimprinting using an AAO template. Then, the coumarin moieties inside each pillar were crosslinked by UV light irradiation to fix the pillar structure. SEM observation confirmed that the internally crosslinked pillar structures were maintained even when immersed in organic solvents such as 1,2-dichloroethane and anisole, which are employed as solvents under SI-ATRP conditions. Finally, poly(2,2,2-trifluoroethyl methacrylate) and poly(N-isopropylacrylamide) chains were grafted onto the thin film by SI-ATRP, respectively, to prepare the hierarchically ordered surface structure. Furthermore, in this study, the surface properties as well as the thermoresponsive hydrophilic/hydrophobic switching of the obtained polymer films were investigated. The surface morphology and chemistry of the films with and without pillar structures were compared, especially the interfacial properties expressed as wettability. Grafting poly(TFEMA) increased the static contact angle for both flat and pillar films, and the con-tact angle of the pillar film surface increased from 104° for the flat film sample to 112°, suggesting the contribution of the pillar structure. Meanwhile, the pillar film surface grafted with poly(NIPAM) brought about a significant change in wettability when changing the temperature between 22 °C and 38 °C. Full article

Despite the promising natural origin, biocompatibility, and biodegradability of chitosan for biomedical applications, developing biodegradable nanocarriers with controllable sizes and precise drug delivery targeting remains a significant challenge, hindering its integration into precision medicine. To address this, we synthesized gold nanocage (AuNCs)/poly-(N-isopropylacrylamide-co-carboxymethyl chitosan) core-shell multifunctional composite nanospheres (CPAu) through a two-step one-pot method. The resulting CPAu nanospheres (~146 nm in size) exhibited multi-sensitive release properties, excellent biocompatibility, and potent photothermal therapy (PTT) activity. These nanospheres effectively encapsulated diverse antitumor drugs while demonstrating triple responsiveness (thermo-, reduction-, and PTT-triggered) for targeted tumor cell delivery, thereby achieving enhanced antitumor efficacy in combinatorial chemotherapy. Full article

Thermosensitive Poly(N-isopropylacrylamide) (PNIPAm) films were synthesized via atmospheric pressure dielectric barrier discharge (APDBD) plasma polymerization. In order to control the thickness of the films, a spin coating technique was used during the deposition of N-isopropylacrylamide (NIPAM) monomer solution onto several glass substrates. We used the coefficient of determination (R-square value) in linear regression to investigate the significance and optimize spin coating parameters during the fabrication of NIPAM coatings before exposure to APDBD plasma to ensure reproducible and uniform film properties. The spin coating parameters investigated in this study include spin speed, spin time, and NIPAM solution concentration with R-square values of 0.978, 0.946, and 0.944, respectively. Also, as a result of the thermosensitive nature of NIPAM, the spin coating operating conditions of temperature and humidity were maintained at 39.0 °C and 15%, respectively. During the APDBD plasma polymerization, argon was used as the discharge gas, and the distance between the two parallel electrodes and plasma frequency were maintained at 5.0 mm and 17 kHz, respectively. The plasma exposure time required for polymerization of PNIPAm coatings was optimized to 60 s. Also, the results showed that a coating with minimal defects had an optimal thickness of 5.18 μm, fabricated under conditions of 90 wt.% NIPAM concentration, spin speed of 4000 rpm, and total spin time of 7 s. Full article

Background/Objectives: Photothermal therapy (PTT) is an emerging minimally invasive strategy in biomedicine that converts near-infrared (NIR) light into localized heat for the targeted inactivation of pathogens and tumor cells. Methods and Results: In this study, we report the synthesis and characterization of thermoresponsive nanogels composed of poly (N-isopropylacrylamide-co-N-isopropylmethylacrylamide) (PNIPAM-co-PNIPMAM) semi-interpenetrated with polypyrrole (PPy), yielding monodisperse particles of 377 nm diameter. Spectroscopic analyses—including ¹H-NMR, FTIR, and UV-Vis—confirmed successful copolymer formation and PPy incorporation, while TEM images revealed uniform spherical morphology. Differential scanning calorimetry established a volumetric phase transition temperature of 38.4 °C, and photothermal assays demonstrated a ΔT ≈ 10 °C upon 10 min of 850 nm NIR irradiation. In vitro antimicrobial activity tests against Pseudomonas aeruginosa (ATCC 15692) showed a dose-time-dependent reduction in bacterial viability, with up to 4 log CFU/mL. Additionally, gentamicin-loaded nanogels achieved 38.7% encapsulation efficiency and exhibited stimulus-responsive drug release exceeding 75% under NIR irradiation. Conclusions: Combined photothermal and antibiotic therapy yielded augmented bacterial killing, underscoring the potential of PPy-interpenetrated nanogels as smart, dual-mode antimicrobials. Full article

Hydrogels are three-dimensional network structures composed of hydrophilic polymers that can swell in water and are very similar to soft tissues such as connective tissue or the extracellular matrix. DNA hydrogels are particularly notable for biomedical applications due to their high biocompatibility, physiological stability, molecular recognition, biodegradability, easy functionalization, and low immunogenicity. Based on these advantages, stimuli-responsive DNA hydrogels that have the property of reversibly changing their structure in response to various microenvironments or molecules are attracting attention as smart nanomaterials that can be applied to biosensing and material transfer, such as in the case of cells and drugs. As DNA nanotechnology advances, DNA can be hybridized with a variety of nanomaterials, from inorganic nanomaterials such as gold nanoparticles (AuNPs) and quantum dots (QDs) to synthetic polymers such as polyacrylamide (PAAm) and poly(N-isopropylacrylamide) (pNIPAM). These hybrid structures exhibit various optical and chemical properties. This review discusses recent advances and remaining challenges in biomedical applications of stimuli-responsive smart DNA hydrogel-based systems. It also highlights various types of hybridized DNA hydrogel, explores various response mechanism strategies of stimuli-responsive DNA hydrogel, and provides insights and prospects for biomedical applications such as biosensing and drug delivery. Full article

Access to clean water remains a critical global challenge, exacerbated by population growth, industrial activity, and climate change. In response, this study presents the development and characterization of thermo-responsive and salt-adaptive ultrafiltration membranes functionalized with a poly(N-isopropylacrylamide)–co-poly(dimethylacrylamide) (PNIPAM-co-PDMAC) copolymer. By combining the thermo-responsive properties of PNIPAM with the hydrophilic characteristics of PDMAC, these membranes exhibit dual-stimuli responsiveness to temperature and ionic strength, allowing for precise control of permeability and fouling resistance. The experimental results demonstrated that the copolymer’s hydration state and dynamic pore size modulation are sensitive to changes in salinity and temperature, with sodium chloride (NaCl) significantly influencing the transition behavior. Preliminary fouling tests confirmed the antifouling capabilities of these membranes, with salt-triggered hydration transitions effectively reducing irreversible fouling and extending membrane durability. The membranes’ reversible properties and adaptability to dynamic operating conditions highlight their potential to enhance the efficiency and sustainability of water treatment processes. Future investigations will focus on scaling up the fabrication process and assessing the long-term stability of these membranes under real-world conditions. This study underscores the promise of smart membrane systems for advancing global water sustainability. Full article

This study employs Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations to investigate interactions between water molecules and Poly(N-isopropylacrylamide) (PNIPAM). DFT reveals preferential water binding sites, with enhanced binding energy observed in the linker zone. Quantum Theory of Atoms in Molecules (QTAIM) and electron localization function (ELF) analyses highlight the roles of hydrogen bonding and steric hindrance. MD simulations unveil temperature-dependent hydration dynamics, with structural transitions marked by changes in the radius of gyration (Rg) and the radial distribution function (RDF), aligning with DFT findings. Our work goes beyond prior studies by combining a DFT, QTAIM and MD simulations approach across different PNIPAM monomer-to-30mer structures. It introduces a systematic quantification of pseudo-saturation thresholds and explores water clustering dynamics with structural specificity, which have not been previously reported in the literature. These novel insights establish a more complete molecular-level picture of PNIPAM hydration behavior and temperature responsiveness, emphasizing the importance of amide hydrogen and carbonyl oxygen sites in hydrogen bonding, which weakens above the lower critical solution temperature (LCST), resulting in increased hydrophobicity and paving the way for understanding water sorption mechanisms, offering guidance for future applications such as dehumidification and atmospheric water harvesting. Full article

Cultural Heritage is a vital socioeconomic driver that must contend with works of art continuously exposed to degradation processes, which are further exacerbated by climate change. Aged coatings, varnishes, and soil can compromise the appearance of artworks, preventing their preservation and valorization. In response, soft matter and colloidal systems, such as nanostructured cleaning fluids (NCFs), have proved to be valuable solutions for safely and effectively cleaning works of art. Here, a novel cleaning system is proposed, for the first time employing microgels of poly(N-isopropylacrylamide) (PNIPAM) with surface chains of oligoethylene glycol methyl ether methacrylate (OEGMA) to favor shear deformation by lubrication. These microgels are loaded with NCFs featuring “green” solvents and different kinds of bio-derived or petroleum-based surfactants (non-ionic, zwitterionic). Rheological characterization of the combined systems highlighted a sharp transition from solid to liquid-like state in the 21–24 °C range when the zwitterionic surfactant dodecyldimethylamine oxide was used; the system displays a solid-like behavior at rest but flows easily at intermediate strains. At slightly higher temperature (>24 °C), an inversion of the G′, G″ values was observed, leading to a system that behaves as a liquid. Such control of rheological behavior is significant for feasible and complete removal of soiled polymer coatings from textured ceramic surfaces, which are difficult to clean with conventional gels, without leaving residues. These results position the PNIPAM-OEGMA microgels as promising cleaning materials for the conservation of Cultural Heritage, with possible applications also in fields where gelled systems are of interest (pharmaceutics, cosmetics, detergency, etc.). Full article

N-isopropylacrylamide and methacrylic acid were copolymerized by a free radical polymerized mechanism. The obtained hydrogel poly(N-isopropylacrylamide-co-methacrylic acid) hydrogels, poly(NIPAM-co-MAA), were utilized as sorbent material for removal Cr(VI), Mn(II), and Pb(II) ions from simulated aqueous solutions. Hydrogel structures before and after heavy metal sorption are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The swelling results indicate that poly(NIPAM-co-MAA) hydrogels are pH- and temperature-sensitive and have high swelling reversibility through three swelling/contraction cycles. The studied parameters of heavy metal sorption include the effect of pH, the initial concentration of heavy metal, the effect of temperature, and the desorption of metal ions. The maximum sorption capacities of poly(NIPAM-co-MAA) hydrogels were determined at pH 4.5 and 25 °C, and they are, for Cr(VI), Mn(II), and Pb(II) ions, 289.35 mg/g, 190.59 mg/g, and 349.71 mg/g, respectively. The pseudo-second-order model and the Langmuir adsorption isotherm best describe the sorption of heavy metal ions onto hydrogels. The removal of heavy metals is an exothermic reaction, and the interaction mechanism between the metal and the hydrogel is primarily physical in nature. Results of three sorption/desorption cycles show a good desorption ratio and sorption capacity of poly(NIPAM-co-MAA) hydrogels. Full article

Poly(N-isopropylacrylamide) (PNIPAm) undergoes a sharp phase transition in aqueous solutions at around 32 °C, which is called the lower critical solution temperature; the tuning of the LCST of PNIPAm could be achieved by the copolymerization of N-isopropylacrylamide (NIPAm) with other hydrophilic/hydrophobic monomers to regulate the solvation state of PNIPAm and meet the requirements of possible applications. Herein, a hydrophilic monomer, 2,3-dihydroxypropyl methacrylate (DHPMA), w introduced to regulate the phase transition behavior of PNIPAm via free radical copolymerization. A series of poly(N-isopropylacrylamide-co-2,3-dihydroxypropyl methacrylate) (P(NIPAm-co-DHPMA)) was synthesized and characterized. The reaction kinetics were investigated in detail. In this copolymerization, the reactivity ratios of DHPMA and NIPAm were found to be 3.09 and 0.11, suggesting that DHPMA had greater preference for homopolymerization than for copolymerization, while NIPAm had greater preference for copolymerization than for homopolymerization. The phase transition temperature of P(NIPAm-co-DHPMA) copolymers varied from 31 to 42 °C by controlling the content of DHPMA in the copolymers from 0 to 58 mol%. Finally, the good cytocompatibility of P(NIPAm-co-DHPMA) was confirmed. These results provide insights into designing thermo-responsive polymers with suitable responsive behaviors that meet the requirements of different applications. Full article

In this study, novel triblock copolymers, including poly(N-isopropylacrylamide)-block-poly(ε-caprolactone)-block-poly(N-isopropylacrylamide) (PNIPAM-b-PCL-b-PNIPAM), poly(N-vinyl-pyrrolidone)-block-poly(ε-caprolactone)-block-poly(N-vinyl-pyrrolidone) (PNVP-b-PCL-b-PNVP), poly(N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate)-block-poly(ε-caprolactone)-block-poly(N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate) (P(DMAEMA-co-NIPAM)-b-PCL-b-P(NIPAM-co-DMAEMA)), and poly(N,N-dimethylacrylamide)-block-poly(ε-caprolactone)-block-poly(N,N-dimethylacrylamide) (PDMA-b-PCL-b-PDMA), were synthesized via a combination of ring-opening polymerization (ROP) and reversible addition–fragmentation chain transfer (RAFT) polymerization. The synthesis was performed using novel bifunctional PCL-based RAFT macro chain transfer agents (macroCTAs; MXTPCL-X1 and MXTPCL-X2) with a m-xylene-bis(2-mercaptoethyloxy) core. Initially, m-xylene-bis(1-hydroxy-3-thia-propane) (MXTOH), which has not previously been used in lactone polymerization, was synthesized via the reaction of α,α′-dibromo-m-xylene with 2-mercaptoethanol in the presence of sodium in ethanol. Subsequently, Sn(Oct)₂-catalyzed ROP of ε-caprolactone (ε-CL) using MXTOH as an initiator yielded PCL-diol (MXTPCLOH). The resulting PCL-diol underwent further functionalization through esterification and substitution reactions, leading to the formation of PCL-based RAFT macroCTAs. Triblock copolymers were synthesized using these macroCTAs with AIBN as an initiator. The synthesized products, along with their intermediates, were characterized using FTIR and ¹H NMR spectroscopy. The number average molecular weight (M_n) and polydispersity index (Ð) of PCL-based macroCTAs were determined by using GPC analysis. The sensor capabilities of the synthesized novel triblock copolymers were investigated on the determination of syringic acid and it was determined that the most sensitive polymer was PNVP-b-PCL-b-PNVP (MXTP2). The working range was between 1.5 µg/mL and 15 µg/mL and the limit of detection (LOD) was found to be 0.44 µg/mL using DPV on MXTP2 polymer sensor. Full article