N-isopropylacrylamide Research Articles

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.

RAFT Polymer-Antibody Conjugation: Squaramide Ester Chemistry Leads to Conjugates with a Therapeutic Anti-EGFR Antibody with Full Retention of Activity and Increased Tumor Uptake In Vivo.

Covalent conjugation of a biologically stable polymer to a therapeutic protein, e.g., an antibody, holds many benefits such as prolonged plasma exposure of the protein and improved tumor uptake. Generation of defined conjugates is advantageous in many applications, and a range of site-selective conjugation methods have been reported. Many current coupling methods lead to dispersity in coupling efficiencies with subsequent conjugates of less-well-defined structure, which impacts reproducibility of manufacture and ultimately may impact successful translation to treat or image diseases. We explored designing stable, reactive groups for polymer conjugation reactions that would lead to conjugates through the simplest and most abundant residue on most proteins, the lysine residue, yielding conjugates in high purity and demonstrating retention of mAb efficacy through surface plasmon resonance (SPR), cell targeting, and in vivo tumor targeting. We utilized squaric acid diesters as coupling agents for selective amidation of lysine residues and were able to selectively conjugate one, or two, high-molecular-weight polymers to a therapeutically relevant antibody, 528mAb, that subsequently retained full binding specificity. Water-soluble copolymers of N-(2-hydroxypropyl) methacrylamide (HPMA) and N-isopropylacrylamide (NIPAM) were prepared by Reversible Addition-Fragmentation chain-Transfer (RAFT) polymerization and we demonstrated that a dual-dye-labeled antibody-RAFT conjugate (528mAb-RAFT) exhibited effective tumor targeting in model breast cancer xenografts in mice. The combination of the precise and selective squaric acid ester conjugation method, with the use of RAFT polymers, leads to a promising strategic partnership for improved therapeutic protein-polymer conjugates having a very-well-defined structure.

A novel dynamic coating medium for single stranded DNA separation in capillary electrophoresis: Thermosensitive hydrogel nanoparticles

Nowadays, research on single-stranded DNA (ssDNA) requires a quick, effective and easy operation method to separate small ssDNA fragments from the organism and ssDNA production process to realize their application in gene therapy and drug diagnosis. Herein, a novel separation matrix of thermosensitive hydrogel nanoparticles (NPs) was proposed, which has been successfully applied to the isolation of biomacromolecules such as enzymes, peptides and proteins, based on the desirable properties of various monomers and advantages, such as high sieving capacity, tunability of hydrophilic and hydrophobic performance and non-toxicity. The flexible particles were prepared by precipitation polymerization method in aqueous solution while N-isopropylacrylamide (NIPAm), acrylic acid (AAc) and N-t-butyl acrylamide (TBAm) was performed as co-monomer, which were first used as the dynamic coating to separate small fragments of ssDNA in capillary electrophoresis (CE). The synthesized NPs were bound to the inner wall of the capillary through non-covalent interactions forming stable dynamic coating to affect the electroosmotic flow and improve the separation reproducibility of ssDNA fragments. Based on the formulation design of NPs and condition optimization of electrophoresis, the running buffer TG (25 mM Tris, 192 mM glycine, pH 8.3) was modified by 4 mg·mL−1 optimized NPs aqueous suspension addition while its molar feed ratio of NIPAm /AAc /TBAm /BIS was 83/5/10/2 and particle size was about 214 nm. Both the formulation design and temperature sensitivity of hydrogel nanoparticles contributed to the DNA separation efficiency. The designed NPs with low viscosity provide an approach to increase their capability as the separation medium for small fragment DNA with important physiological functions great potential and promise.

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.

The Influence of Amphoteric Terpolymerization of Poly (N-Isopropylacrylamide) in the Optimization of the Phase Separation Temperatures

The aim of this study is to fabricate an ampholyte thermo-responsive terpolymers and explore the influence of ampholyte on the phase separation temperatures in different pH solutions. The fabrication of the ampholyte thermo-responsive terpolymers was achieved by terpolymerization of N-isopropylacrylamide (NIPAAm), DIVA (5, 10, and 15 mol.%), and acrylic acid (AA) 10 mol.%. The preparation of the cationic monomer from vanillin was achieved in a facile reaction named 2-((diisopropylamino) methyl)-4-formyl-6-methoxyphenyl acrylate (DIVA). The chemical structures of the monomers and terpolymers were evaluated successfully by 1H, 13C NMR, and FTIR. The average molecular weight and dispersity of the terpolymers were characterized using gel permeation chromatography (GPC); the glass transition temperature, crystallinity, and morphology were characterized using DSC, XRD, and SEM, respectively. The hydrophilic/hydrophobic properties of the fabricated terpolymers, at different pH conditions, were evaluated using contact angle measurements. The lower critical solution temperature (LCST) for all samples was measured using UV–vis spectrophotometer. Moreover, the LCST was tested using different Hofmeister salts in kosmotropic and chaotropic conditions. The findings of this study can be utilized in the bio-separation of biological molecules, as well as drug delivery applications.Graphical

Synthesis and characterization of PNM@IAM core-shell microgels through inverse emulsion polymerization and its application for heavy metal ions capture

In this study, thermo and pH-sensitive multifunctional poly (N-isopropylacrylamide-co- N,N’-methylenebisacrylamide, Poly(NIPAAm-co-MBA) - (N-4-amino-2-methylene-4-oxobutanoic acid, IAM) named as (PNM@IAM) core-shell microgels are synthesized by inverse microemulsion polymerization technique using two monomers, N-isopropylacrylamide (NIPAAm) and N-4-amino-2-methylene-4-oxobutanoic acid (IAM). The formation of the microgels are confirmed by 1H nuclear magnetic resonance (1H NMR) and attenuated total reflection fourier transform infrared (ATR-FTIR) spectra. The light transmittance study shows that the microgels prepared at different concentrations and pHs exhibit different physical properties. The phase transition temperature is increased with the addition of IAM. Dynamic light scattering (DLS) analysis reveals that the swelling of the microgels at basic environment is due to the deprotonation of the weak acid groups in IAM. The metal ion chelating test shows that the core-shell PNM@IAM could effectively absorb metal ions in highly basic environment. The absorption and release of heavy metal ions from aqueous solution could be controlled by adjusting the pH of the reaction environment.

Preparation and characterization of N-isopropyl acrylamide grafted polyvinyl alcohol and chitosan blend films with hydrophobic and antibacterial properties

One of Polyvinyl alcohol (PVA) films' well-recognized weaknesses is moisture sensitivity, which limits their applications. Various techniques have been employed to improve their hydrophobicity, such as blending and hydrophobic coating, but they have shown issues with compatibility and stability. In this study, a new method was proposed to modify PVA by grafting N-isopropyl acrylamide (NIPA) and blending it with chitosan (CS) to enhance its hydrophobic and antibacterial properties. The chemical structure of PVA-NIPA was characterized by FT-IR, 1H NMR, and XRD. By forming chemical bonds between PVA and NIPA through Michael's addition reaction, the moisture sensitivity of the film was significantly reduced. Additionally, the contact angle (CA) increased to 107.85° and the water vapor transmission rate (WVTR) decreased from 17.69 g / (m2h) to 6.53 g / (m2h). The PVA-NIPA/CS film also exhibited excellent mechanical properties, with Young's modulus of 303.67 MPa, tensile strength of 28.86 MPa, and elongation at break of 330.25%. Moreover, it showed better compatibility, high transparency, good UV-blocking properties, and strong antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), reducing the total colony counts by 2.53 and 3.44 logs, respectively. Thus, this work has generated new insights for expanding the application range of PVA films in packaging materials.

Preparation and characterization of a mussel-inspired and programmable PDA@MXene/PNIPAM hydrogel actuator with ultrafast temperature and NIR responsiveness

In recent years, smart hydrogels have been widely applied to various types of hydrogel actuators due to their unique stimulus responsibility, such as temperature responsiveness, near-infrared (NIR) light responsiveness, pH responsiveness, etc. Herein, segmented poly (N-isopropyl acrylamide) (PNIPAM) based hydrogel actuators with both temperature and NIR light actuation behaviors were constructed. Polydopamine (PDA) was firstly used to modify MXene nanosheets to fabricate an efficient photothermal conversion material. Then they were added into PNIPAM matrix to prepare PDA@MXene/PNIPAM hydrogels. The prepared PDA@MXene/PNIPAM hydrogels exhibited three-dimensional network structure with the tensile strength of 26.84 kPa, and they were successfully assembled into segmented hydrogel actuators. The assembled segmented hydrogel actuator exhibited high bending angle of 470° in 1.75 s in 55 °C hot water and bending angle of 203° in 15 s when irradiated by 6 W/cm2 NIR light. The segmented hydrogel actuators displayed good programmable actuation performance. Finally, they were applied as smart devices, such as hydrogel hook for grasping object, switch for controlling circuit and valve for governing fluid flow. This work provides a novel strategy for fabricating programmable hydrogel actuators and will inspire new ideas and constructions for smart soft hydrogel actuators.

Temperature-Sensitive Modified Bentonite Based on NIPAM for Drilling Fluid: Experimental and Molecular Simulation Studies.

Bentonite is an important component of drilling fluid, whose quality directly affects the safety and economic benefits of water-based drilling fluid. In order to effectively cope with temperature changes, the development of temperature-sensitive modified bentonite is of great significance. In this study, a temperature-sensitive modified bentonite based on NIPAM with excellent temperature sensitivity was developed through intercalation modification. The temperature-sensitive bentonite (CMC-B-NIPAM) was prepared by grafting N-isopropyl acrylamide (NIPAM) onto the surface of calcium bentonite through the dehydration condensation of silane coupling agent KH570 after the intercalation of sodium Carboxymethyl Cellulose (CMC). The synthesis indexes of CMC-B and CMC-B-NIPAM were optimized by the single-factor method. CMC-B-NIPAM was characterized by XRD and FTIR. The temperature sensitivity, rheology, suspensibility, and expansion capacity of CMC-B-NIPAM dispersion were investigated. The results showed that CMC-B-NIPAM had good temperature sensitivity, and the rheological properties of its dispersion showed characteristics of steady flow and temperature thickening in the range of 40-70 °C. A molecular simulation model was established to observe the microsynthesis mechanism of temperature-sensitive modified bentonite based on NIPAM. The results of this study show that CMC-B-NIPAM drilling fluid has the function of ensuring the stability of drilling fluid flow patterns compared to traditional drilling fluids.

Drug controlled releasing system based on polypyrrole modified multi-responsive hydrogel constructed from methacrylic acid and N-isopropylacrylamide

Stimuli-responsive hydrogels could effectively solve the problem that traditional drug carriers were difficult to deliver drug on-demand. However, some shortcomings such as complex preparation, single responsiveness, and narrow application still needed to be urgently overcome. In view of this situation, two kinds of hydrogels were elaborately designed in this work. In the unique ethanol/water mixed solvent, a homogeneous reaction system consisting of methacrylic acid (MAA) and N-isopropylacrylamide (NIPAM) was constructed, and a dual-responsive P(MAA-co-NIPAM) hydrogel was successfully synthesized. A near-infrared (NIR) responsive multi-functional PPy/P(MAA-co-NIPAM) hydrogel was subsequently prepared by the introduction of polypyrrole (PPy) via in-situ polymerization. NIR-responsive swelling, photodeformable, and photothermal ability of the hydrogel under NIR light irradiation were explored. It was found that rapid shape and temperature change could be achieved within 60 s for PPy/P(MAA-co-NIPAM) hydrogel. With doxorubicin as a model drug, the drug loading and in vitro controlled releasing behaviors under different conditions were comprehensively investigated. It was confirmed that the multi-responsive hydrogels had controllable drug releasing ability under different stimulations, which would realize potential targeted drug delivery in physiological environment. This work might provide a new synthetic method of hydrogel for drug releasing, which was expected to expand the potential application domain of hydrogel materials in NIR penetration targeted therapy.

L-Lysine-Modified pNIPAm-co-GMA Copolymer Hydrogel for pH- and Temperature-Responsive Drug Delivery and Fluorescence Imaging Applications.

The development of dual-stimuli-responsive hydrogels attracts much research interest owing to its unique stimuli-responsive characteristics. In this study, a poly-N-isopropyl acrylamide-co-glycidyl methacrylate-based copolymer was synthesized by incorporating N-isopropyl acrylamide (NIPAm) and a glycidyl methacrylate (GMA) monomer. The synthesized copolymer, pNIPAm-co-GMA was further modified with L-lysine (Lys) functional units and further conjugated with fluorescent isothiocyanate (FITC) to produce a fluorescent copolymer pNIPAAm-co-GMA-Lys hydrogel (HG). The in vitro drug loading and dual pH- and temperature-stimuli-responsive drug release behavior of the pNIPAAm-co-GMA-Lys HG was investigated at different pH (pH 7.4, 6.2, and 4.0) and temperature (25 °C, 37 °C, and 45 °C) conditions, respectively, using curcumin (Cur) as a model anticancer drug. The Cur drug-loaded pNIPAAm-co-GMA-Lys/Cur HG showed a relatively slow drug release behavior at a physiological pH (pH 7.4) and low temperature (25 °C) condition, whereas enhanced drug release was achieved at acidic pH (pH 6.2 and 4.0) and higher temperature (37 °C and 45 °C) conditions. Furthermore, the in vitro biocompatibility and intracellular fluorescence imaging were examined using the MDA-MB-231 cell line. Therefore, we demonstrate that the synthesized pNIPAAm-co-GMA-Lys HG system with temperature- and pH-stimuli-responsive features could be promising for various applications in biomedical fields, including drug delivery, gene delivery, tissue engineering, diagnosis, antibacterial/antifouling material, and implantable devices.

Conjugation of Candida rugosa lipase with hydrophobic polymer improves esterification activity of vitamin E in nonaqueous solvent

We described a novel polymer-lipase conjugate for high-efficient esterification of vitamin E using vitamin E and succinic anhydride as the substrates in nonaqueous media. In this work, the monomer, N-isopropylacrylamide (NIPAM), was grafted onto Candida rugosa lipase (CRL) to synthesize poly(NIPAM) (pNIPAM)-CRL conjugate by atom transfer radical polymerization via the initiator coupled on the surface of CRL. The result showed that the catalytic efficiencies of pNIPAM-CRL conjugates (19.5–30.3 L·s−1·mmol−1) were at least 7 times higher than that of free CRL (2.36 L·s−1·mmol−1) in DMSO. It was attributed to a significant increase in Kcat of the conjugates in nonaqueous media. The synthesis catalyzed by pNIPAM-CRL conjugates was influenced by the length and density of the grafted polymer, water content, solvent polarity and molar ratio of the substrates. In the optimal synthesis, the reaction time was shortened at least 7 times, and yields of vitamin E succinate by pNIPAM-g-CRL and free CRL were obtained to be 75.4% and 6.6% at 55 °C after the reaction for 1.5 h. The result argued that conjugation with pNIPAM induced conformational change of the lid on CRL based on hydrophobic interaction, thus providing a higher possibility of catalysis-favorable conformation on CRL in nonaqueous media. Moreover, pNIPAM conjugation improved the thermal stability of CRL greatly, and the stability improved further with an increase of chain length of pNIPAM. At the optimal reaction conditions (55 °C and 1.5 h), pNIPAM-g-CRL also exhibited good reusability in the enzymatic synthesis of vitamin E succinate and kept ∼70% of its catalytic activity after ten consecutive cycles. The research demonstrated that pNIPAM-g-CRL was a more competitive biocatalyst in the enzymatic synthesis of vitamin E succinate and exhibited good application potential under harsh industrial 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.

Microcontact-Imprinted Optical Sensors for Virulence Factors of Periodontal Disease.

Periodontitis (gum disease) is a common biofilm-mediated oral condition, with around 7% of the adult population suffering from severe disease with risk for tooth loss. Moreover, periodontitis virulence markers have been found in atherosclerotic plaque and brain tissue, suggesting a link to cardiovascular and Alzheimer's diseases. The lack of accurate, fast, and sensitive clinical methods to identify patients at risk leads, on the one hand, to patients being undiagnosed until the onset of severe disease and, on the other hand, to overtreatment of individuals with mild disease, diverting resources from those patients most in need. The periodontitis-associated bacterium, Porphyromonas gingivalis, secrete gingipains which are highly active proteases recognized as key virulence factors during disease progression. This makes them interesting candidates as predictive biomarkers, but currently, there are no methods in clinical use for monitoring them. Quantifying the levels or proteolytic activity of gingipains in the periodontal pocket surrounding the teeth could enable early-stage disease diagnosis. Here, we report on a monitoring approach based on high-affinity microcontact imprinted polymer-based receptors for the Arg and Lys specific gingipains Rgp and Kgp and their combination with surface plasmon resonance (SPR)-based biosensor technology for quantifying gingipain levels in biofluids and patient samples. Therefore, Rgp and Kgp were immobilized on glass coverslips followed by microcontact imprinting of poly-acrylamide based films anchored to gold sensor chips. The monomers selected were N-isopropyl acrylamide (NIPAM), N-hydroxyethyl acrylamide (HEAA) and N-methacryloyl-4-aminobenzamidine hydrochloride (BAM), with N,N'-methylene bis(acrylamide) (BIS) as the crosslinker. This resulted in imprinted surfaces exhibiting selectivity towards their templates high affinity and selectivity for the templated proteins with dissociation constants (K d) of 159 and 299 nM for the Rgp- and Kgp-imprinted, surfaces respectively. The former surface displayed even higher affinity (K d = 71 nM) when tested in dilute cell culture supernatants. Calculated limits of detection for the sensors were 110 and 90 nM corresponding to levels below clinically relevant concentrations.

Aliquots of MIL-140 and Graphene in Smart PNIPAM Mixed Hydrogels: A Nanoenvironment for a More Eco-Friendly Treatment of NaCl and Humic Acid Mixtures by Membrane Distillation.

The problem of water scarcity is already serious and risks becoming dramatic in terms of human health as well as environmental safety. Recovery of freshwater by means of eco-friendly technologies is an urgent matter. Membrane distillation (MD) is an accredited green operation for water purification, but a viable and sustainable solution to the problem needs to be concerned with every step of the process, including managed amounts of materials, membrane fabrication procedures, and cleaning practices. Once it is established that MD technology is sustainable, a good strategy would also be concerned with the choice of managing low amounts of functional materials for membrane manufacturing. These materials are to be rearranged in interfaces so as to generate nanoenvironments wherein local events, conceived to be crucial for the success and sustainability of the separation, can take place without endangering the ecosystem. In this work, discrete and random supramolecular complexes based on smart poly(N-isopropyl acrylamide) (PNIPAM) mixed hydrogels with aliquots of ZrO(O2C-C10H6-CO2) (MIL-140) and graphene have been produced on a polyvinylidene fluoride (PVDF) sublayer and have been proven to enhance the performance of PVDF membranes for MD operations. Two-dimensional materials have been adhered to the membrane surface through combined wet solvent (WS) and layer-by-layer (LbL) spray deposition without requiring further subnanometer-scale size adjustment. The creation of a dual responsive nanoenvironment has enabled the cooperative events needed for water purification. According to the MD's rules, a permanent hydrophobic state of the hydrogels together with a great ability of 2D materials to assist water vapor diffusion through the membranes has been targeted. The chance to switch the density of charge at the membrane-aqueous solution interface has further allowed for the choice of greener and more efficient self-cleaning procedures with a full recovery of the permeation properties of the engineered membranes. The experimental evidence of this work confirms the suitability of the proposed approach to obtain distinct effects on a future production of reusable water from hypersaline streams under somewhat soft working conditions and in full respect to environmental sustainability.

Effect of Poly(Vinyl Alcohol) Concentration and Chain Length on Polymer Nanogel Formation in Aqueous Dispersion Polymerization.

Nanotechnology has attracted increasing interest in various research fields for fabricating functional nanomaterials. In this study, we investigated the effect of poly(vinyl alcohol) (PVA) addition on the formation and thermoresponsive properties of poly(N-isopropyl acrylamide)-based nanogels in aqueous dispersion polymerizations. During dispersion polymerization, PVA appears to play three roles: (i) it bridges the generated polymer chains during polymerization, (ii) it stabilizes the formed polymer nanogels, and (iii) it regulates the thermoresponsive properties of the polymer nanogels. By regulating the bridging effect of PVA via changing the PVA concentration and chain length, the size of the obtained polymer gel particles was maintained in the nanometer range. Furthermore, we found that the clouding-point temperature increased when using low-molecular weight PVA. We believe that the knowledge gained in this study regarding the effect of PVA concentration and chain length on nanogel formation will aid in the future fabrication of functional polymer nanogels.

Copolymerization of zwitterionic sulfobetaine and hydrophobic acrylamide based antifouling electrochemical biosensors for detection of CA125 in clinical serum samples

It is crucial to construct antifouling electrochemical biosensors with long-term stability and high sensitivity for the detection of biomarkers in complex biological environments to prevent the unspecific adsorption of proteins and other biomolecules. Herein, a glassy carbon electrode electropolymerization with polyaniline (PANI/GCE) was further modified with a copolymerization (PSN) of zwitterionic sulfobetaine methacrylate (SBMA) and hydrophobic N-isopropyl acrylamide (NIPAM) by simple hydrophobic interaction to construct an antifouling biosensor. PSN forms a stable self-assembled monolayer on the PANI/GCE surface and exhibits good antifouling performance in serum due to the advantages of hydrophobic anchoring and the antifouling performance of zwitterionic polymers. Ascribe to the large specific surface area and excellent conductivity, the present biosensor can detect CA125 in undiluted samples in the range of 0.01–1000 U mL−1 with a limit of detection of 2.7 mU mL−1 (3σ/k). Both with good biocompatibility and biological stability, PSN modified sensing surface realizes a long-term antifouling for 15 days in a buffer solution. The present work provides a simple strategy for the direct analysis of CA125 in human serum without a complicated construction of biosensors, indicating the potential application in clinical diagnosis.

In situ preparation of PNIPAM biphasic hydrogels

N-isopropylacrylamide (NIPAM) monomer undergoes phase separation in water at very high concentrations, which offers striking opportunities to engineer biphasic hydrogel systems. However, this is a metastable state and NIPAM evolves to crystallize. Besides, the concentration of NIPAM in the lower phase is very small. In this work we show that the aforementioned limitations can be overcome by the incorporation of selected components. Thus, the addition of acrylic acid enables accessing remarkably stable biphasic NIPAM-water systems, as corroborated by DSC (absence of NIPAM crystallization). The addition of a third monomer, diallyldimethylammonium chloride (DDAC), further allows modifying NIPAM partition notably. The phase-distribution of the components for different monomer mixtures was gauged by 1H NMR. Subsequent polymerization leads to the formation of biphasic hydrogels systems in a single step, whose phase morphology and temperature response (swelling response) has been characterized by SEM. This methodology also permits adjusting the crosslinker partition as a function of its nature, which can be used to tune the swelling behaviour of each phase for a certain composition.

3D printed thermo-responsive electroconductive hydrogel and its application for motion sensor

Stimulus-responsive hydrogels with excellent conductivity have been widely used in electrical, electrochemical, biomedical, and other fields. It is still a challenge to prepare gels with high conductivity. In this paper, poly (N-isopropyl acrylamide) is 3D printed by changing the rheological properties of the printing solution with clay. By forming phytic acid cross-linked polyaniline conductive polymer network in situ on the poly (N-isopropyl acrylamide) matrix, 3D printing of thermally responsive conductive hybrid hydrogels was realized. The interpenetrating polymer network structure provides an electron transport path for hydrogels. The hydrogels have high porosity, strong interaction, high electrical conductivity, high thermal response sensitivity, and significant mechanical enhancement. The results show that the swelling and mechanical properties of the gel are influenced by soaking in different concentrations. The application scenario of the hydrogel was confirmed by a temperature-sensitive switch and finger motion detection.

Facile construction of irinotecan loaded mesoporous nano-formulation with surface-initiated polymerization to improve stimuli-responsive drug delivery for breast cancer therapy

This work uses rice husk to fabricate mesoporous silica nanoparticles (D-RMN) for breast cancer therapy. The biocompatible dual-responsive (DAN-RMN) was developed by polymerizing acrylic acid (AA) and n-isopropyl acrylamide (NIPAM) on the DV-RMN surface monomeric ratio to increase drug delivery efficiency after vinyl groups were added to the surface of nanoparticles (DAN-RMN). Various analytical and spectroscopical methods characterized the fabricated nanoparticles. Additionally, further encapsulation with SN-38 into the DAN-RMN enhances anticancer efficiency. The in-vitro controlled SN-38 release displayed remarkable temperature and pH response. The MTT assay established the biocompatibility and cytotoxicity of natural sources of silica and DAN-RMN. The fabricated SN-38@DAN-RMN nanoparticles effectively killed the MDA-MB-231 and 4T1 cancerous cells, confirmed by the MTT assay. The IC50 values of SN-38@DAN-RMN in MDA-MB-231 and 4T1 for 1.8 μg/mL and 1.7 μg/mL, respectively. In addition, acridine orange-ethidium bromide (AO-EB) dual staining methods were used to determine morphological changes of cell shrinkage and fragmentation. Nuclear staining methods confirmed the nuclear fragmentation and condensation of the cells. Further, the cell death was examined using dual staining Annexin V-FITC/PI in flow cytometric analyses to assess apoptosis in the MDA-MB-231 and 4T1 cell lines. The apoptotic cell ratio of SN-38@DAN-RMN in MDA-MB-231 and 4T1 for 27.8 and 32.8, respectively. Since there is no drug leakage in the blood while the carrier is in circulation, the DAN-RMN nanocarrier may be used for targeted and stimuli-responsive administration using ultrasound imaging.