Sensitive Poly Research Articles

Phase transition in polymer hydrogels investigated by swelling, DSC, FTIR and NMR

AbstractThe swelling and thermal behavior of single (SN) and double network (DN) hydrogels containing polyacrylamide (PAAm) and temperature sensitive poly(N, N-diethylacrylamide) (PNNDEAAm) were investigated by gravimetry and differential scanning calorimetry (DSC). Changes of the hydration of carbonyl groups and mobility of polymer network chains in the hydrogels with temperature were studied by Fourier-transformed infrared and proton nuclear magnetic resonance (1H NMR) spectroscopy. The enthalpy of dissociation of the hydrophobic interaction, minimum and maximum numbers of water molecules per monomer unit in PNNDEAAm SN hydrogel involved in the hydrophobic hydration were determined by DSC. The volume phase transition accompanied by expulsion/uptake of water and heat absorption/release in heating/cooling was exhibited by all DN hydrogels containing PNNDEAAm. In these hydrogels, above the phase transition temperature, the population of hydrated carbonyls is enriched with the free and single hydrated ones in the same way as in the aqueous solution of linear PNNDEAAm and mobility of the PNNDEAAm chains is strongly reduced. Presence of the PAAm network does not influence the phase transition temperature but strongly reduces the enthalpy of the phase transition, promotes higher degrees of hydration of carbonyls, and increases mobility of the PNNDEAAm chains in the mixed hydrogels above the phase transition temperature.

X-ray Activated Nanoprodrug for Visualization of Cortical Microvascular Alterations and NIR-II Image-Guided Chemo-Radiotherapy of Glioblastoma.

The permeability of the highly selective blood-brain barrier (BBB) to anticancer drugs and the difficulties in defining deep tumor boundaries often reduce the effectiveness of glioma treatment. Thus, exploring the combination of multiple treatment modalities under the guidance of second-generation near-infrared (NIR-II) window fluorescence (FL) imaging is considered a strategic approach in glioma theranostics. Herein, a hybrid X-ray-activated nanoprodrug was developed to precisely visualize the structural features of glioma microvasculature and delineate the boundary of glioma for synergistic chemo-radiotherapy. The nanoprodrug comprised down-converted nanoparticle (DCNP) coated with X-ray sensitive poly(Se-Se/DOX-co-acrylic acid) and targeted Angiopep-2 peptide (DCNP@P(Se-DOX)@ANG). Because of its ultrasmall size and the presence of DOX, the nanoprodrug could easily cross BBB to precisely monitor and localize glioblastoma via intracranial NIR-II FL imaging and synergistically administer antiglioblastoma chemo-radiotherapy through specific X-ray-induced DOX release and radiosensitization. This study provides a novel and effective strategy for glioblastoma imaging and chemo-radiotherapy.

Temperature modulated sustainable on/off photosynthesis switching of microalgae towards hydrogen evolution.

Despite great progress in the active interfacing between various abiotic materials and living organisms, the development of a smart polymer matrix with modulated functionality of algae towards the application of green bioenergy is still rare. Herein, we design a thermally sensitive poly(N-isopropylacrylamide)-co-poly(butyl acrylate) with an LCST (ca. 25 °C) as a chassis, which could co-assemble with algal cells based on hydrophobic interaction to generate a new type of robust hybrid hydrogel living material. By modulating the temperature to 30 °C, the volume of the polymer matrix is shrunk by 9 times, which allows the formation of physical shading and metabolism changing of the algae, and then triggers the functionality switching of the algae from photosynthetic oxygen production to hydrogen production. By contrast, by decreasing the temperature to 20 °C, the hybrid living materials go into a sol state where the algae behave normally with photosynthetic oxygen production. In particular, due to the proliferation of the algae in living materials, a long-term and exponential enhancement in the amount of hydrogen produced is achieved. Overall, it is anticipated that our investigations could provide a new paradigm for the development of polymer/living organism-based hybrid living materials with synergistic functionality boosting green biomanufacturing.

Glycine recalibrates iron homeostasis of lens epithelial cells by blocking lysosome-dependent ferritin degradation

One of the major pathological processes in cataracts has been identified as ferroptosis. However, studies on the iron metabolism mechanism in lens epithelial cells (LECs) and the methods of effectively alleviating ferroptosis in LECs are scarce. Along these lines, we found that in the ultraviolet radiation b (UVB) induced cataract model in vitro and in vivo, the ferritin of LECs is over-degraded by lysosomes, resulting in the occurrence of iron homeostasis disorder. Glycine can affect the ferritin degradation through the proton-coupled amino acid transporter (PAT1) on the lysosome membrane, further upregulating the content of nuclear factor erythrocyte 2 related factor 2 (Nrf2) to reduce the damage of LECs from two aspects of regulating iron homeostasis and alleviating oxidative stress. By co-staining, we further demonstrate that there is a more sensitive poly-(rC)-binding protein 2 (PCBP2) transportation of iron ions in LECs after UVB irradiation. Additionally, this study illustrated the increased expression of nuclear receptor coactivator 4 (NCOA4) in NRF2-KO mice, indicating that Nrf2 may affect ferritin degradation by decreasing the expression of NCOA4. Collectively, glycine can effectively regulate cellular iron homeostasis by synergistically affecting the lysosome-dependent ferritin degradation and PCBP2-mediated ferrous ion transportation, ultimately delaying the development of cataracts.

Highly sensitive self-powered piezoelectric poly(vinylidene fluoride)-based nanofibrous mat containing microporous metal–organic framework nanostructures for energy harvesting applications

Highly sensitive self-powered piezoelectric poly(vinylidene fluoride)-based nanofibrous mat containing microporous metal–organic framework nanostructures for energy harvesting applications

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.

Highly Selective Uricase-Based Quantification of Uric Acid Using Hydrogen Peroxide Sensitive Poly-(vinylpyrrolidone) Templated Copper Nanoclusters as a Fluorescence Probe

We reported on uric acid (UA) detection using a new fluorescence-based assay: poly-(vinylpyrrolidone) templated copper nanoclusters (PVP-CuNCs) with uricase in an aqueous medium, such as human urine with uricase. These nanoclusters were synthesized in a simple wet chemical method and their morphological and optical properties were examined with the aid of high-resolution transmission electron microscopy and optical absorbance/emission spectroscopy. The PVP-CuNCs acted as the fluorescence indicators that used the enzyme-catalyzed oxidation of UA with uricase. Adding UA into the hybrid PVP-CuNCs/uricase solution caused enzyme-catalyzed oxidation to occur, producing hydrogen peroxide (H2O2), allantoin, and carbon dioxide. The fluorescence intensity of PVP-CuNCs is decreased by this biocatalytically generated H2O2, and this decrease is proportional to the UA level. A calibration plot showed the linear relationship with the negative slope between fluorescence intensity and UA in the range of 5–100 × 10−7 mol/L. The limit of detection (LOD) of UA was estimated as 113 × 10−9 mol/L. This fluorescent probe turned out to be highly specific for UA over other biologically relevant molecules. The demonstrated capability of the PVP-CuNCs as the nanoprobes for quantification of the UA levels in human urine samples could potentially pave the way toward medical applications where a super-sensitive, cost-effective, and UA-specific diagnosis was required.

Synthesis of a temperature sensitive graft carbon dioxide‐based copolymer and its evaluation as a nano drug carrier

AbstractIn this study, a temperature sensitive graft carbon dioxide‐based copolymer, poly (propylene oxide‐co‐carbon dioxide‐co‐allyl glycidyl ether)‐poly (N‐isopropylacrylamide)‐polyethylene glycol monomethyl ether (PPAG‐PNIPAm‐mPEG) was synthesized by “Click Chemistry”. The hydrophobic main chain, PPAG, was prepared by the copolymerization of propylene oxide (PO) and allyl glycidyl ether (AGE). The branch chains include hydrophilic mPEG and temperature sensitive poly (N‐isopropylacrylamide). The structure of the polymer was characterized by 1H NMR and IR spectroscopy. Avermectin (AVE) was loaded into the nanoparticles to form PPAG‐PNIPAm‐mPEG@AVE nanoparticles. PPAG‐PNIPAm‐mPEG could self‐assemble into nano‐sized micelles in aqueous solution. And the size, zeta potential, critical micelle concentration (CMC) of PPAG‐PNIPAm‐mPEG nanoparticles can be altered by changing the lengths of the PNIPAm segments. The loading rate and encapsulation rate of PPAG‐PNIPAm‐mPEG@AVE were 36.98% and 89.98% respectively. The temperature sensitiveness of the nanomaterials was confirmed by DLS. The results show that temperature has a certain effect on the AVE release rate of PPAG‐PNIPAm‐mPEG@AVE in vitro. With the decrease of PNIPAm chain length, the AVE release rate decreases, and the contact angle of PPAG‐PNIPAm‐mPEG@AVE decreases compared with that of water.

Electrochemical detection and quantification of catechol based on a simple and sensitive poly(riboflavin) modified carbon nanotube paste electrode

In the present research work, selective and sensitive catechol (CT) detection and quantification were shown in the presence of resorcinol (RS) in 0.2 M phosphate buffer (PB) solution by preparing a low-cost, simple, and green carbon nanotube paste electrode (CNTPE) surface activated with electropolymerized riboflavin (PRF). The morphological, conductivity, and electrochemical features of the modified electrode (PRFMCNTPE) and bare carbon nanotube paste electrode (BCNTPE) materials were analyzed using electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The PRF-activated electrode displays outstanding sensitivity, stability, selectivity, reproducibility, and repeatability for the redox feature of CT with improved electrochemical current and declined electrochemical potential compared to BCNTPE. The peak currents of CT are correlated to the different CT concentrations (CV method: 6.0–60.0 μM & DPV method: 0.5–7.0 μM), and the obtained detection limit (DL) and quantification limit (QL) are found to be 0.025 μM and 0.085 μM (CV method) and 0.0039 μM and 0.0132 μM (DPV method), respectively. The prepared PRFMCNTPE material was advantageous for the examination of CT in environmentally important tap water sample as a real-time application.

Acidity/carbon dioxide-sensitive triblock polymer-grafted photoactivated vesicles for programmed release of chemotherapeutic drugs against glioblastoma.

Controllable release of chemotherapeutic drugs in tumor sites remains a big challenge for precision therapy. Herein, we developed acidity/carbon dioxide (H+/CO2)-sensitive poly (ethylene glycol)-b-poly (2-(diisopropylamino) ethyl methacrylate)-b-polystyrene triblock polymer (PEG-b-PDPA-b-PS) grafted photoactivated vesicles for programmed release of chemotherapeutic drugs against glioblastoma. In brief, gold nanoparticles (GNPs) were firstly tethered with the H+/CO2-sensitive PEG-b-PDPA-b-PS polymer. Next, the CO2 precursor (ammonium bicarbonate, NH4HCO3) and doxorubicin (DOX) were loaded during self-assembly process of PEG-b-PDPA-b-PS-tethered GNPs, thus obtaining the multifunctional gold vesicles (denoted as GVND). The programmed multi-stimuli responsive drug release by GVND was undergone in multiple steps as follows: 1) the vesicular architecture of GVND was first swelled in tumor acidic microenvironment, 2) the GVND were partially broken under near-infrared (NIR) laser irradiation, 3) the mild hyperthermia generated by GV triggered the thermal decomposition of encapsulated NH4HCO3, leading to the in situ generation of CO2, 4) the generated CO2 reacted with PDPA of PEG-b-PDPA-b-PS, changing the hydrophilicity and hydrophobicity of GVND, thus vastly breaking its vesicular architecture, finally resulting in a "bomb-like" release of DOX in tumor tissues. Such a multi-stimuli responsive programmed drug delivery and mild hyperthermia under NIR laser activation displayed strong antitumor efficacy and completely eradicated U87MG glioblastoma tumor. This work presented a promising strategy to realize precision drug delivery for chemotherapy against glioblastoma. STATEMENT OF SIGNIFICANCE.

Dual thermo-responsive multifunctional ionic conductive hydrogel by salt modulation strategy for multilevel encryption and visual monitoring

Despite the current progress in thermo-responsive materials, it is still a significant challenge to develop superior multiple temperature-sensitive ionic conductive hydrogels with programmable regulation capability for interactive wearable iontronics. Here, a dual thermo-responsive ionic conductive hydrogel (DTICH) is constructed based on a salt modulation strategy, which cleverly integrates low-temperature sensitive sodium dodecyl sulfate (SDS) and high-temperature sensitive poly(N-isopropylacrylamide) PNIPAm-based polymer. Owing to the common ion effect and salting-out effect, the resultant DTICH hydrogel visually presents wide and tunable dual temperature response behaviors of 0-18℃ (Tk) and 37-80℃ (LCST) by controlling NaCl concentration for the first time. Meanwhile, benefiting from the synergy of NaCl and thermo-sensitive materials, the hydrogel is concurrently endowed with excellent stretchability (>900 %), adhesion (adhesion strength >30 kPa), frost resisting (-40℃) and multilevel encryption functions. More importantly, the DTICH hydrogel can ingeniously perceive mechanical force and external temperature via the changes of relative resistance and transparency, which can be applied as human–computer interfaces to interactively monitor human motions and temperatures in real time. Therefore, our study establishes a brand new and effective route for the rational design and fabrication of high-level visual interactive devices and smart wearable iontronics.

Coumarin end-capped poly(ε-caprolactone)-poly(ethylene glycol) tri-block copolymer: synthesis, characterization and light-response behavior

Light responsive polymeric materials are of great interest for several applications; in particular, the NIR spectrum is considered an ideal light source for e.g. biomedical applications. Here, we have designed light sensitive poly(ɛ-caprolactone)- poly(ethylene glycol)-poly(ɛ-caprolactone) (PCL-PEG-PCL) triblock copolymer, end-capped with modified coumarin. When dialyzed against water, the coumarin-functionalized triblock copolymers self-assembled into core-shell nanoparticles, characterized by DLS, SEM, and NMR. The hydrophobic Nile Red, used as a model guest molecule, was loaded in the nanoparticles and its release by light irradiation of selected wavelength was demonstrated by fluorescence spectroscopy. When irradiated with UV or NIR light, coumarin end-groups of the copolymer were photolyzed, converting the end groups to carboxylic acids, thus provoking the disruption of the preassembled nanoparticles, and the release of the encapsulated guest molecule.

A smart cotton fabric with adaptive moisture management through temperature sensitive poly(2-hydroxyethyl-6-(vinyl amino)hexanoate) finishing

A smart cotton fabric with adaptive moisture management through temperature sensitive poly(2-hydroxyethyl-6-(vinyl amino)hexanoate) finishing

Flexible and Transparent Composite Electrode with 3D Freestanding Architecture for Dopamine Monitoring

AbstractDevelopment of a flexible, transparent, and air‐permeable dopamine (DA) sensor is highly desirable for fully integrated optoelectrochemical probes, which can provide a useful tool for closed‐loop control and monitoring neural activities. Herein, a 3D freestanding architecture, which integrates a flexible and transparent metallic micromesh as the “core” with DA sensitive poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) as the “shell,” has been developed for DA monitoring. The freestanding micromesh electrode shows not only high mechanical flexibility (without apparent performance variation after 100 bending times), high optical transparency (≈85% at 550 nm), and air permeability (≈2600 mm s−1 at 10 Pa), but also excellent DA sensing performance such as a sensitivity up to 1650 µAcm−2 mM−1, wide linear range from 1 × 10−6 to 1000 × 10−6 m, a low limit of detection (LOD) of 0.27 × 10−6 m, high selectivity and high stability. The outstanding performance may arise from the core‐shell micromesh configuration, which combines high electrical conductivity of the Ni micromesh and high electrocatalytic activity of the PEDOT:PSS layer for DA oxidation. Such 3D freestanding architecture offers a simple and effective methodology to construct implantable biosensors for monitoring of DA and other neurotransmitters in the brain.

Highly Sensitive, Ultrastretchable, and Degradable PCT-CNT Strain Sensor for Continuous Monitoring of Male Erectile Dysfunction

Male erectile dysfunction (ED) has been attracting significant attention due to its serious effect on emotional damage, heavy psychological blow, and life quality. Nevertheless, it is still a challenge to score and monitor ED more conveniently, comfortably, and in real-time with ease at home. Herein, a highly sensitive strain poly (CL-co-TOSUO) (PCT)-carbon nanotube (CNT) sensor with ultrastretchable and degradable ability was designed and fabricated. The proposed PCT-CNT exhibited excellent mechanical properties, its strain can reach up to 2368%, and its tensile strength is over 12 MPa. A fast degradation rate of the PCT-CNT could also be acquired, completely degrading in 8 h in a tetrahydrofuran solution at room temperature. It is worth emphasizing that the proposed PCT-CNT could be assembled as a wearable flexible sensor with practical application potential in male ED detection, which has an excellent signal response with the bending and stretching of the simulated module.

Dual-sensitive drug-loaded hydrogel system for local inhibition of post-surgical glioma recurrence

Local treatment after resection to inhibit glioma recurrence is thought to able to meet the real medical needs. However, the only clinically approved local glioma treatment-wafer containing bis(2-chloroethyl) nitrosourea (BCNU) showed very limited effects. Herein, in order to inhibit tumor recurrence with prolonged and synergistic therapeutic effect of drugs after tumor resection, an in situ dual-sensitive hydrogel drug delivery system loaded with two synergistic chemo-drugs BCNU and temozolomide (TMZ) was developed. The thermosensitive hydrogel was loaded with reactive oxygen species (ROS)-sensitive poly (lactic-co-glycolic) acid nanoparticles (NPs) encapsulating both BCNU and TMZ and also free BCNU and TMZ. The in vitro synergistic effect of BCNU and TMZ and in vivo presence of ROS at the residual tumor site were confirmed. The prepared ROS-sensitive NPs and thermosensitive hydrogel, as well as the long-term release behavior of drugs and NPs, were fully characterized both in vitro and in vivo. After >90% glioblastoma resection, the dual-sensitive hydrogel drug delivery system was injected into the resection cavity. The median survival time of the experimental group reached 65days which was twice as long as the Resection only group, implying that this in situ drug delivery system effectively inhibited tumor recurrence. Overall, this study provides new ideas and strategies for the inhibition of postoperative glioma recurrence.

Investigation of poloxamer cell protective ability via shear sensitive aggregates in stirred aerated bioreactor

Mammalian cell cultivation in bioreactors is widely practiced in the pharmaceutical industry for production of monoclonal antibodies, vaccines and other therapeutic products. During cell culture, ensuring homogeneity and oxygen transport to the cultivation broth is essential for survival and proper cell growth. Due to the lack of a cell wall, mammalian cells are prone to damage by the gas aeration. Common practice how to protect mammalian cells against hydrodynamic forces is usage of poloxamers – synthetic, water-soluble nonionic copolymers. However, poloxamers are never pure compounds and the distribution of molecular weight strongly depends on the production process. This may lead to the final product containing impurities, which may have a negative impact on the protectivity of cells. Therefore, it is of high importance to know whether a particular poloxamer can be used as a cell protective agent. In this paper, we extend the usability of our method based on shear sensitive poly(methyl methacrylate) (PMMA) aggregate probes to investigate the protective capability of poloxamers. Comparative study of three different poloxamers and their impact on maximum effective hydrodynamic stress (τmax) and mass transfer coefficient (kLa) is conducted in the bench-scale 3.5 L Minifors bioreactor.

Development of a sensitive trial-ready poly(GP) CSF biomarker assay for C9orf72-associated frontotemporal dementia and amyotrophic lateral sclerosis

ObjectiveA GGGGCC repeat expansion in the C9orf72 gene is the most common cause of genetic frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). As potential therapies targeting the repeat expansion...

Biobased thermo/pH sensitive poly(N-isopropylacrylamide-co-crotonic acid) hydrogels for targeted drug delivery

Materials sensitive to external stimuli are recognized as safe and effective tool able to respond to specific demands in the therapy of various diseases. Thermo sensitive hydrogels based on poly(N-isopropylacrylamide) (P(NIPAAM)) are widely investigated for targeted drug delivery. Still, the abundance of the stimuli in the human body often requires more than one responsive group able to act simultaneously to achieve optimal therapeutic effects. Due to its pH sensitivity and bio-based production, crotonic acid (CA) was a monomer of choice for preparation of eco-friendly copolymer hydrogels based on NIPAAM and CA (P(NIPAAMcoCA)), which turned to be thermo and pH sensitive at the same time. The potential of the P(NIPAAMcoCA) system for encapsulation and controlled release of drugs with different solubility was investigated engaging water-soluble lidocaine hydrochloride and poorly water-soluble ibuprofen as model drugs. The hydrogels were characterized by various technics: FTIR, DSC, SEM and single compressive tests, while swelling behavior and controlled release of the drugs were analyzed with respect to the CA amount in two environments with different pH values at 25 °C and 37 °C. It was demonstrated that due to their dual responsiveness the P(NIPAAMcoCA) hydrogels have potential for controlled release of drugs with different solubility.

Synthesis and application of a temperature sensitive poly(N-vinylcaprolactam-co-N,N-diethyl acrylamide) for low-temperature rheology control of water-based drilling fluid

During deepwater drilling operation, the wellbore temperature decreases with the increase of water depth, and increases rapidly with the increase of formation depth. Temperature sensitive polymers can change the molecular conformation with temperature, and then change its hydrophobicity, to adjust the network structure between solid particles and polymer in drilling fluid. In this paper, a novel temperature sensitive copolymer poly(N-vinylcaprolactam-co-N,N-diethyl acrylamide) (PNVDE) was synthesized. Its molecular structure, molecular weight and molecular weight distribution were characterized. The effects of salinity, pH value and copolymer concentrations on lower critical solution temperature (LCST) were studied. Based on the temperature sensitive property of the copolymer, the ability to control the low-temperature rheology of water-based drilling fluid (WBDF) was studied. The results showed that PNVDE can effectively control the rheology of deepwater WBDF in the range of 4~ 60 ℃. At the same time, the experiments of temperature and salt resistance showed that the copolymer has strong ability of temperature resistance and salt resistance, and can withstand the temperature alternation of drilling fluid. The synergistic effect of PNVDE and bentonite made the rheology of deepwater drilling fluid stable, which can be explained by “SASA Hydrogen Bond Network”.