Hydrogel Nanoparticles Research Articles

Facile synthesis and application of aluminum oxide nanoparticle based biodegradable film

AbstractThis study focuses on the synthesis of aluminum oxide nanoparticles (AlO‐NPs) hydrogel through in situ method and formation of biopolymer nanocomposite film. UV–Vis spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), particle size analyzer, and energy dispersive X‐ray spectrum were performed for the characterization of AlO‐NPs. TEM micrograph demonstrates the presence of AlO‐NPs in the range of 50–100 nm in the hydrogel network made from sugarcane bagasse carboxymethyl cellulose (SB‐CMC) and synthetic carboxymethyl cellulose (CMC). The successful absorptions peak at 210 nm while conducting UV–Vis spectroscopy suggests existence of AlO‐NPs. The antibacterial properties of AlO‐NPs were analyzed using the disc plate diffusion technique against Gram‐negative bacteria: Escherichia coli (ATCC 433); and Gram‐positive bacteria: Bacillus subtilis (ATCC 1688). AlO‐NPs present in CMCs films reduce moisture content, solubility; elongation at break and increases films' tensile strength.

Translational Studies on the Potential of a VEGF Nanoparticle-Loaded Hyaluronic Acid Hydrogel.

Heart failure has a five-year mortality rate approaching 50%. Inducing angiogenesis following a myocardial infarction is hypothesized to reduce cardiomyocyte death and tissue damage, thereby preventing heart failure. Herein, a novel nano-in-gel delivery system for vascular endothelial growth factor (VEGF), composed of star-shaped polyglutamic acid-VEGF nanoparticles in a tyramine-modified hyaluronic acid hydrogel (nano-VEGF-HA-TA), is investigated. The ability of the nano-VEGF-HA-TA system to induce angiogenesis is assessed in vivo using a chick chorioallantoic membrane model (CAM). The formulation is then integrated with a custom-made, clinically relevant catheter suitable for minimally invasive endocardial delivery and the effect of injection on hydrogel properties is examined. Nano-VEGF-HA-TA is biocompatible on a CAM assay and significantly improves blood vessel branching (p < 0.05) and number (p < 0.05) compared to a HA-TA hydrogel without VEGF. Nano-VEGF-HA-TA is successfully injected through a 1.2 m catheter, without blocking or breaking the catheter and releases VEGF for 42 days following injection in vitro. The released VEGF retains its bioactivity, significantly improving total tubule length on a Matrigel® assay and human umbilical vein endothelial cell migration on a Transwell® migration assay. This VEGF-nano in a HA-TA hydrogel delivery system is successfully integrated with an appropriate device for clinical use, demonstrates promising angiogenic properties in vivo and is suitable for further clinical translation.

Abiotic Stimuli-Responsive Protein Affinity Reagent for IgG.

We describe an approach for the discovery of protein affinity reagents (PARs). Abiotic synthetic hydrogel copolymers can be "tuned" for selective protein capture by the type and ratios of functional monomers included in their polymerization and by the polymerization conditions (i.e., pH). By screening libraries of hydrogel nanoparticles (NPs) containing charged and hydrophobic groups against a protein target (IgG), a stimuli-responsive PAR is selected. The robust carbon backbone synthetic copolymer is rapidly synthesized in the chemistry laboratory from readily available monomers. The production of the PAR does not require living cells and is free from biological contamination. The capture and release of the protein by the copolymer NP is reversible. IgG is sequestered from human serum at pH 6.5 and following a wash step, the purified protein is released by elevating the pH to 7.3. The binding and release of the protein occur without denaturation. The abiotic material functions as a selective PAR for the F(ab')2 domain of IgG for pull-down and immunoprecipitation experiments and for isolation and purification of proteins from complex biological mixtures.

Immobilization of TiO2 Nanoparticles in Hydrogels Based on Poly(Methyl Acrylate) and Succinamide Acid for the Photodegradation of Organic Dyes

Hydrogels have excellent properties that make them ideally suited as host matrices for the immobilization of photoreactive materials such as TiO2 nanoparticles that serve as catalysts in the photodegradation of organic dyes, which is of great importance in practical water pollution treatment applications. However, the application of hydrogels for this purpose remains poorly studied. The present study addresses this issue by developing two types of hydrogels based on poly(methyl acrylate) and succinamide acid with embedded TiO2 nanoparticles for use as photocatalysts in the photodegradation of organic dyes. The results of the analysis demonstrate that the TiO2 nanoparticles are distributed uniformly in the hydrogel matrices, and the hydrogels maintain their original structures after use. The photodegradation efficiencies of the developed TiO2-hydrogels are demonstrated to be reasonably close to that of freely distributed TiO2 nanoparticles in solution for four different organic dyes. In addition, the results of degradation-regeneration cycling tests demonstrate that immobilizing the TiO2 nanoparticles into the hydrogels greatly reduces their loss during utilization, and the photocatalysts can be easily reused. In fact, the two TiO2-hydrogels retain reasonably high photocatalytic degradation performance after four degradation-regeneration cycles.

Systematic Development and Characterization of Novel, High Drug-Loaded, Photostable, Curcumin Solid Lipid Nanoparticle Hydrogel for Wound Healing.

The study aims to develop high drug-loaded (about 15% lipid matrix) curcumin solid lipid nanoparticles (CSLNs) for wound healing. CSLNs prepared by hot, high-pressure homogenization, without using organic solvents, were optimized using the Taguchi design followed by the central composite design. The optimized CSLNs exhibited a high assay/drug content (0.6% w/w), solubility (6 × 105 times), and EE (75%) with a particle size < 200 nm (PDI—0.143). The CSLNs were safe (in vitro and in vivo), photostable, autoclavable, stable up to one year at 30 °C and under refrigeration and exhibited a controlled release (zero-order; 5 days). XRD, FTIR, and DSC confirmed solubilization and entrapment of the curcumin within the SLNs. TEM and FESEM revealed a smooth and spherical shape. The CSLNs showed a significant antimicrobial effect (MIC of 64 µg/mL for planktonic cells; 512 µg/mL for biofilm formation; and 2 mg/mL for mature biofilm) against Staphylococcus aureus 9144, while free curcumin dispersion did not exhibit any effect. This is the first report on the disruption of mature biofilms by curcumin solid lipid nanoparticles (CSLNs). The cell proliferation potential of CSLNs was also evaluated in vitro while the wound healing potential of CSLNs (incorporated in a hydrogel) was assessed in vivo. In (i) nitrogen mustard gas and (ii) a full-thickness excision wound model, CSLNs exhibited (a) significantly faster wound closure, (b) histologically and immunohistochemically better healing, (c) lower oxidative stress (LPO) and (d) inflammation (TNFα), and (e) increased angiogenesis (VEGF) and antioxidant enzymes, i.e., catalase and GSH levels. CSLNs thus offer a promising modern wound therapy especially for infected wounds, considering their effects in mature biofilm disruption.

Design, fabrication and drug release potential of dual stimuli-responsive composite hydrogel nanoparticle interfaces

Nanocomposite hydrogel particles grasp considerable attention in nanotechnology and nanomedicine as one of the potential drug delivery platforms. However, prevail a coveted drug delivery strategy with sustain and stimuli-drug release is still challenging. Herein, poly (N-(4-aminophenyl) methacrylamide))-carbon nano-onions (PAPMA-CNOs = f-CNOs)/diclofenac-complex integrated chitosan (CS) nanocomposite hydrogel nanoparticles (CNPs) were fabricated using an ionic gelation strategy. CNPs possess several conducive physicochemical properties, including spherical morphology and uniform particle distribution.In vitro drug release from CNPs was vetted in different pHs of gastrointestinal (GI) tract environment at a temperature range of 37−55 °C and found dual (pH and thermo)-responsive controlled drug release. Under pH 7.4, CNPs exhibited the highest drug release at 55 °C in 15 days. The drug release results disclose that the structure of CNPs was disassembled at 55 °C to release the encapsulated drug molecules in a controlled fashion. The CNPs also displayed good cell viability against human fibroblast cells. Thus, all the results together unveil that CNPs would thrive as a promising pH and temperature-triggered drug delivery platform for the GI tract and colon targeted drug delivery.

Freezing-Assisted Conjugation of Unmodified Diblock DNA to Hydrogel Nanoparticles and Monoliths for DNA and Hg2+ Sensing.

Acrydite-modified DNA is the most frequently used reagent to prepare DNA-functionalized hydrogels. Herein, we show that unmodified penta-adenine (A5 ) can reach up to 75 % conjugation efficiency in 8 h under a freezing polymerization condition in polyacrylamide hydrogels. DNA incorporation efficiency was reduced by forming duplex or other folded structures and by removing the freezing condition. By designing diblock DNA containing an A5 block, various functional DNA sequences were attached. Such hydrogels were designed for ultrasensitive DNA hybridization and Hg2+ detection, with detection limits of 50 pM and 10 nM, respectively, demonstrating the feasibility of using unmodified DNA to replace acrydite-DNA. The same method worked for both gel nanoparticles and monoliths. This work revealed interesting reaction products by exploiting freezing and has provided a cost-effective way to attach DNA to hydrogels.

Freezing‐Assisted Conjugation of Unmodified Diblock DNA to Hydrogel Nanoparticles and Monoliths for DNA and Hg2+ Sensing

AbstractAcrydite‐modified DNA is the most frequently used reagent to prepare DNA‐functionalized hydrogels. Herein, we show that unmodified penta‐adenine (A5) can reach up to 75 % conjugation efficiency in 8 h under a freezing polymerization condition in polyacrylamide hydrogels. DNA incorporation efficiency was reduced by forming duplex or other folded structures and by removing the freezing condition. By designing diblock DNA containing an A5 block, various functional DNA sequences were attached. Such hydrogels were designed for ultrasensitive DNA hybridization and Hg2+ detection, with detection limits of 50 pM and 10 nM, respectively, demonstrating the feasibility of using unmodified DNA to replace acrydite‐DNA. The same method worked for both gel nanoparticles and monoliths. This work revealed interesting reaction products by exploiting freezing and has provided a cost‐effective way to attach DNA to hydrogels.

Catalytic Reduction of Organic Dyes by Multilayered Graphene Platelets and Silver Nanoparticles in Polyacrylic Acid Hydrogel

Graphene oxide has been widely used in the oxidative degradation of environmental pollutants. However, its catalytic role can be questioned as graphene oxide with oxygen-containing functional groups may also act as reactant in oxidative reactions. Herein, hydrogel composites loaded with multilayered graphene platelets showed excellent catalytic performance for the reduction of a wastewater organic pollutant (methylene blue) under NaBH4, which proved the catalytic role of multilayered graphene platelets. The liquid-based direct exfoliation method was used to prepare two-dimensional materials, which is compatible with other liquid phase methods to prepare nanomaterials. Hydrogel composites composed of multilayered graphene platelets, silver nanoparticles, and polyacrylic acid hydrogels were synthesized in water solution under irradiation with ultraviolet light, demonstrating the advantages of synthesizing nanocomposites using the liquid-based direct exfoliation method.

Nanogels: An overview of properties, biomedical applications, future research trends and developments

Nanogels in biomedical field are promising and innovative materials as dispersions of hydrogel nanoparticles based on crosslinked polymeric networks that have been called as next generation drug delivery systems due to their relatively high drug encapsulation capacity, uniformity, tunable size, ease of preparation, minimal toxicity, stability in the presence of serum, and stimuli responsiveness. Nanogels show a great potential in chemotherapy, diagnosis, organ targeting and delivery of bioactive substances. The main subjects reviewed in this article concentrates on: (i) Nanogel assimilation in the nanomedicine domain; (ii) Features and advantages of nanogels, the main characteristics, such as: swelling capacity, stimuli sensitivity, the great surface area, functionalization, bioconjugation and encapsulation of bioactive substances, which are taken into account in designing the structures according to the application; some data on the advantages and limitations of the preparation techniques; (iii) Recent progress in nanogels as a carrier of genetic material, protein and vaccine. Recent tremendous developments in their synthesis open access to systems with complex architectures and compositions allowing for tailoring microgels with specific properties. At the same time state-of-the-art theoretical and simulation approaches offer deeper understanding of the behavior and structure of nano- and microgels under external influences and confinement at interfaces or at high volume fractions. Developments in the experimental analysis of nano- and microgels have become particularly important for structural investigations covering a broad range of length scales relevant to the internal structure, the overall size and shape, and interparticle interactions in concentrated samples. Here we summarize emerging research of nanogewls for biomedical applications and provide an overview of the state-of-the-art, recent developments as well as emerging trends in the field of nano- and microgels.

Targeting Nanostrategies for Imaging of Atherosclerosis

Despite the progress in cardiovascular research, atherosclerosis still represents the main cause of death worldwide. Clinically, the diagnosis of Atherosclerotic Cardiovascular Disease (ASCVD) relies on imaging methodologies including X-ray angiography and computed tomography (CT), which however still fails in the identification of patients at high risk of plaque rupture, the main cause of severe clinical events as stroke and heart attack. Magnetic resonance imaging, which is characterized by very high spatial resolution, could provide a better characterization of atherosclerotic plaque (AP) anatomy and composition, aiding in the identification of “vulnerable” plaques. In this context, hydrogel matrices, which have been demonstrated able to boost relaxometric properties of Gd-based contrast agents (CAs) by the effect of Hydrodenticity, represent a valuable tool towards the precision imaging of ASCVD improving the performance of this class of CAs while reducing systemic toxicity. In particular, hydrogel nanoparticles encapsulating Gd-DTPA can further contribute to providing CA-specific accumulation in the AP by nanoparticle surface decoration triggering an active targeting of the AP with the overall effect of allowing an earlier and more accurate diagnosis. In this work, we tested crosslinked Hyaluronic Acid Nanoparticles (cHANPs) in the complex environment of human atherosclerotic plaque. In addition, the surface of cHANPs was decorated with the antibody anti-CD36 (Ab36-cHANPs) for the active targeting of AP-associated macrophages. Results demonstrate that the Hydrodenticity of cHANPs and Ab36-cHANPs is preserved in this complex system and, preliminarily, that interaction of these probes with the AP is present.

Ameliorating quercetin constraints in cancer therapy with pH-responsive agarose-polyvinylpyrrolidone -hydroxyapatite nanocomposite encapsulated in double nanoemulsion

Despite quercetin (QC) promising features for cancer therapy, low solubility, poor permeability, and short biological half-life time significantly confine its application in cancer therapy. In this study, a novel approach is developed to improve loading efficiency and attain quercetin sustained-release concurrently. In this direction, hydrogel nanocomposite of agarose (AG)-polyvinylpyrrolidone (PVP)-hydroxyapatite (HAp) was loaded with QC. Incorporating HAp nanoparticles in the AG-PVP hydrogel improved the loading efficiency up to 61%. Also, the interactions between nanoparticle, drug, and hydrogel polymers rendered the nanocomposite pH-responsive at acidic conditions and controlled the burst release at neutral conditions. Then, QC-loaded hydrogel was encapsulated into the water in oil in water nanoemulsions to further sustain the drug release. As a result, the pH-responsive release of QC with prolonged-release over 96 h was observed. In more detail, according to the Korsmeyer-Peppas mathematical model, the mechanism of release was anomalous (diffusion-controlled) at pH 7.4 and anomalous transport (dissolution-controlled) at pH 5.4. The presence of all nanocomposite components was confirmed with FTIR analysis, and XRD results approved the incorporation of QC in the fabricated nanocomposite. The homogeneous surface of the nanocomposite in FESEM images showed good compatibility between components. The zeta potential analysis confirmed the good stability of the nanocarriers. Besides, the fabricated AG-PVP-HAp-QC platform showed significant cytotoxicity on MCF-7 cells compared to QC as a free drug (p < 0.001) and to quercetin-loaded AG-PVP (AG-PVP-QC) (p < 0.001) with enhanced apoptosis induction after the addition of HAp. Accordingly, this delivery platform ameliorated loading and sustained-release of QC, as well as its anticancer activity by releasing the drug at an effective therapeutic level over a long period to induce apoptosis. Thus, turning this drug delivery system into a potential candidate for further biomedical applications.

Effect of Different Surface-Charged Lamellar Materials on Swelling Properties of Nanocomposite Hydrogels

This study investigated the effect of different surface-charged lamellar materials on the swelling and diffusion properties of synthesized polyacrylamide-methylcellulose hydrogels (HG). Montmorillonite and thermally activated hydrotalcite (300 °C and 550 °C) were incorporated during the preparation of nanocomposite (NC) hydrogels. A series of NC hydrogels were prepared by varying the lamellar material content (1:1, 2:1 and 4:1). The results showed that the HG with hydrotalcite (550 °C) was strongly dependent on the ionic intensity, and that the swelling degree increased by 50%, 65% and 78% with reducing the hydrotalcite content at (1:1), (2:1) and (4:1), respectively. The water absorption capacity of HG containing montmorillonite or hydrotalcite (300 ºC) was slightly affected when the pH was decreased from 7 to 3. However, the pH variation from 7 to 10 increased the water absorption capacity of most HG, except those containing hydrotalcite (550 °C) at (2:1) and (4:1). The presence of lamellar nanoparticles in hydrogels made the polymer matrix more rigid, and less likely to absorb water. In contrast, HG with hydrotalcite (550 °C) at (2:1) and (4:1) showed anomalous behavior with an increase in their water absorption capacity. The results support that the developed NC-HG can be suitable candidate materials for controlled released applications.

Emerging Role of Hydrogels in Drug Delivery Systems, Tissue Engineering and Wound Management.

The popularity of hydrogels as biomaterials lies in their tunable physical properties, ability to encapsulate small molecules and macromolecular drugs, water holding capacity, flexibility, and controllable degradability. Functionalization strategies to overcome the deficiencies of conventional hydrogels and expand the role of advanced hydrogels such as DNA hydrogels are extensively discussed in this review. Different types of cross-linking techniques, materials utilized, procedures, advantages, and disadvantages covering hydrogels are tabulated. The application of hydrogels, particularly in buccal, oral, vaginal, and transdermal drug delivery systems, are described. The review also focuses on composite hydrogels with enhanced properties that are being developed to meet the diverse demand of wound dressing materials. The unique advantages of hydrogel nanoparticles in targeted and intracellular delivery of various therapeutic agents are explained. Furthermore, different types of hydrogel-based materials utilized for tissue engineering applications and fabrication of contact lens are discussed. The article also provides an overview of selected examples of commercial products launched particularly in the area of oral and ocular drug delivery systems and wound dressing materials. Hydrogels can be prepared with a wide variety of properties, achieving biostable, bioresorbable, and biodegradable polymer matrices, whose mechanical properties and degree of swelling are tailored with a specific application. These unique features give them a promising future in the fields of drug delivery systems and applied biomedicine.

Mechanical Properties of a Supramolecular Nanocomposite Hydrogel Containing Hydroxyl Groups Enriched Hyper-Branched Polymers.

Owing to highly tunable topology and functional groups, hyper-branched polymers are a potential candidate for toughening agents, for achieving supramolecular interactions with hydrogel networks. However, their toughening effects and mechanisms are not well understood. Here, by means of tensile and pure shear testings, we characterise the mechanics of a nanoparticle–hydrogel hybrid system that incorporates a hyper-branched polymer (HBP) with abundant hydroxyl end groups into the matrix of the polyacrylic acid (PAA) hydrogel. We found that the third and fourth generations of HBP are more effective than the second one in terms of strengthening and toughening effects. At a HBP content of 14 wt%, compared to that of the pure PAA hydrogel, strengths of the hybrid hydrogels with the third and fourth HBPs are 2.3 and 2.5 times; toughnesses are increased by 525% and 820%. However, for the second generation, strength is little improved, and toughness is increased by 225%. It was found that the stiffness of the hybrid hydrogel is almost unchanged relative to that of the PAA hydrogel, evidencing the weak characteristic of hydrogen bonds in this system. In addition, an outstanding self-healing feature was observed, confirming the fast reforming nature of broken hydrogen bonds. For the hybrid hydrogel, the critical size of failure zone around the crack tip, where serious viscous dissipation occurs, is related to a fractocohesive length, being about 0.62 mm, one order of magnitude less than that of other tough double-network hydrogels. This study can promote the application of hyper-branched polymers in the rapid evolving field of hydrogels for improved performance.

Selective capture of circulating tumor cells by antifouling nanostructure substrate made of hydrogel nanoparticles

The detection and analysis of circulating tumor cells (CTCs) from cancer patients' blood samples present a powerful means to monitor cancer progression. In this work, an antifouling nanostructure substrate made of hydrogel nanoparticles was fabricated for an effective capture of CTCs from the blood samples. The hydrogel nanoparticles were synthesized by zwitterionic sulfobetaine methacrylate (SBMA), methacrylic acid (MAA) and N, N’-methylene bisacrylamide (MBA) through a simple polymerization. SBMA could provide an effective antifouling layer for the substrate to prevent nonspecific cell adhesion, MAA could afford active carboxyl groups for the immobilization of antibody to achieve specific CTC capture, and the nanostructured surface could improve the interaction of the target cells with the antibody modified substrate surface to enhance the capture efficiency of CTCs. Moreover, it was not necessary to further modify the antifouling molecules on the hydrogel nanoparticle substrate's surface, reducing the complexity and difficulty of the substrate preparation. The results showed that about 87 % of target cells (MCF-7 cells) were captured on the antibody modified hydrogel nanoparticle substrate. In contrast, the substrate showed little adhesive capacity for the nonspecific cells (K562 cells), and only 0.15 % of cells were captured. And 98 % of the captured cells kept good cell viability. Finally, 1–32 CTCs/mL were detected from the blood samples of five cancer patients, while no CTC was found in five healthy samples. It is envisaged that the new hydrogel nanostructure substrate is capable of capturing CTCs efficiently and specifically from patient blood samples to be used in cancer treatment.

Detection of toxoplasmic encephalitis in HIV positive patients in urine with hydrogel nanoparticles.

Diagnosis of toxoplasmic encephalitis (TE) is challenging under the best clinical circumstances. The poor clinical sensitivity of quantitative polymerase chain reaction (qPCR) for Toxoplasma in blood and CSF and the limited availability of molecular diagnostics and imaging technology leaves clinicians in resource-limited settings with few options other than empiric treatment. Here we describe proof of concept for a novel urine diagnostics for TE using Poly-N-Isopropylacrylamide nanoparticles dyed with Reactive Blue-221 to concentrate antigens, substantially increasing the limit of detection. After nanoparticle-concentration, a standard western blotting technique with a monoclonal antibody was used for antigen detection. Limit of detection was 7.8pg/ml and 31.3pg/ml of T. gondii antigens GRA1 and SAG1, respectively. To characterize this diagnostic approach, 164 hospitalized HIV-infected patients with neurological symptoms compatible with TE were tested for 1) T. gondii serology (121/147, positive samples/total samples tested), 2) qPCR in cerebrospinal fluid (11/41), 3) qPCR in blood (10/112), and 4) urinary GRA1 (30/164) and SAG1 (12/164). GRA1 appears to be superior to SAG1 for detection of TE antigens in urine. Fifty-one HIV-infected, T. gondii seropositive but asymptomatic persons all tested negative by nanoparticle western blot and blood qPCR, suggesting the test has good specificity for TE for both GRA1 and SAG1. In a subgroup of 44 patients, urine samples were assayed with mass spectrometry parallel-reaction-monitoring (PRM) for the presence of T. gondii antigens. PRM identified antigens in 8 samples, 6 of which were concordant with the urine diagnostic. Our results demonstrate nanoparticle technology's potential for a noninvasive diagnostic test for TE. Moving forward, GRA1 is a promising target for antigen based diagnostics for TE.

Preparation of agarose xerogel nanoparticles by solvent evaporation from water nanodroplets

We developed a W/O miniemulsion reactor system enabling the preparation of biopolymer nanoparticles and control of their morphologies and inner microstructures. First, the W/O miniemulsion was prepared by suspending water nanodroplets containing agarose in oil. Then, we produced agarose hydrogel nanoparticles (AgarH) by the gelation of agarose in nanodroplets. Next, we prepared agarose xerogel nanoparticles (AgarX) by precisely tuning the water evaporation from AgarH. We controlled the morphologies (solid and hollow) and crystal structure of AgarX by changing the pressure and temperature during water evaporation. In fact, AgarX with a hollow structure was generated through rapid evaporation at a low pressure. AgarH was dissolved in Milli-Q water when the temperature was raised to 90 °C. On the other hand, AgarX remained a solid particle under the same conditions, likely because of its high crystallinity. We expect that this technique can be applied to prepare xerogels of diverse biomass-based polymers for the replacement of synthetic polymers. We developed a W/O miniemulsion reactor system enabling the preparation of biopolymer nanoparticles and control of their morphologies and inner microstructures. We produced agarose hydrogel nanoparticles (AgarH) by the gelation of agarose in nanodroplets of a W/O miniemulsion. Next, we prepared agarose xerogel nanoparticles (AgarX) by precisely tuning the water evaporation from AgarH. We controlled the morphologies (solid and hollow) and crystal structure of AgarX by changing the pressure and temperature. The resultant AgarX possessed high crystallinity and thereby exhibited water resistance better than AgarH.

ROMP synthesis of gallol-containing polymer hydrogels for in situ fabrication of AuNPs and AgNPs composites as recyclable catalysts for the degradation of 4-nitrophenol

Metal nanoparticle composite hydrogels (MNCHs) have attracted considerable attention in the catalytic field because hydrogels can provide appropriate microenvironment and enable catalysts to be conveniently separated and recycled. Here, a novel and well-defined gallol-functionalized hydrogel Gel-G was synthesized by ring-opening metathesis polymerization (ROMP). The resulting hydrogel Gel-G can be used as template to in situ prepare catalytically active gold nanoparticles hydrogel (AuNPs-Gel-G) and sliver nanoparticles hydrogel (AgNPs-Gel-G) without use of any external reductant based on the strong reducibility and coating property of the gallol moiety. The two MNCHs were well characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Both AuNPs-Gel-G and AgNPs-Gel-G exhibited high catalytic activity for the 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP), and can be easily separated and reused at least five times.

Particle and Gel Characterization of Irinotecan-Loaded Double-Reverse Thermosensitive Hydrogel

The irinotecan-loaded double-reverse thermosensitive hydrogel (DRTH) is a dispersed system of irinotecan-loaded solid lipid nanoparticles (SLN) in a thermosensitive hydrogel. To optimise the particle and gel properties of DRTHs for rectal administration of irinotecan, SLNs and DRTHs were prepared with tricaprin, triethanolamine, Tween 80, and Span 20. Among the SLNs tested, an SLN composed of 1 g irinotecan, 0.5 g lipid mixture, and 0.5 g combined surfactant gave the highest entrapment efficiency and smallest particle size. A DRTH composed of (poloxamer 407/poloxamer 188/combined surfactant/SLN dispersion/H2O (10/15/17/4/54%)) showed easy administration, fast gelling, and strong gel-forming in the body.