Influences of NaCl and Na2SO4 on the Micellization Behavior of the Mixture of Cetylpyridinium Chloride + Polyvinyl Pyrrolidone at Several Temperatures

Herein, the conductivity measurement technique is used to determine the interactions that may occur between polyvinyl pyrrolidone (PVP) polymer and cetylpyridinium chloride (CPC) surfactant in the presence of NaCl and Na2SO4 of fixed concentration at variable temperatures (298.15–323.15 K) with an interval of 5 K. In the absence or presence of salts, we observed three critical micelle concentrations (CMC) for the CPC + PVP mixture. In all situations, CMC1 values of CPC + PVP system were found to be higher in water than in attendance of salts (NaCl and Na2SO4). Temperature and additives have the tendency to affect counterion binding values. Various physico-chemical parameters were analyzed and demonstrated smoothly, including free energy (ΔG0m), enthalpy (ΔH0m) and entropy change (ΔS0m). The micellization process is achieved to be spontaneous based on the obtained negative ΔG0m values. The linearity of the ΔHmo and ΔSmo values is excellent. The intrinsic enthalpy gain (ΔH0*m) and compensation temperature (Tc) were calculated and discussed with logical points. Interactions of polymer hydrophobic chains or the polymer + surfactant associated with amphiphilic surface-active drugs can employ a strong impact on the behavior of the gels.

Enhanced Antioxidant Activity of Fresh Fruits through Salicylic Acid/β-CD Hydroalcoholic Gels

Oxidation is an important cause of fruit spoilage, and therefore improving the antioxidant capacity of fresh fruits is beneficial to their preservation. Herein, fresh-cut bananas were used as a type of fresh fruit and soaked in 75% hydroalcoholic gels containing salicylic acid (SA) or SA/β-CD inclusion complex (SA/β-CD). After treatment, they were placed in an atmosphere at 85% relative humidity at 20 °C for 12 days. A significant reduction in spoilage in bananas treated with the hydroalcoholic gels in the presence of SA/β-CD was observed, compared with those treated with gels in the presence or absence of SA. The free-radical-scavenging performances of SA and its complex were investigated using the DPPH (1,1-diphenyl-2-picryl-hydrazil) method. Based on the results, the significant increase in antioxidant activity was attributed to the fact that the inclusion complex could break the intramolecular hydrogen bonding of SA, thus efficiently eliminating ROS in the fruits. The formation of the inclusion complex was confirmed by experiments and theoretical calculations. Our findings indicate that treatment with SA/β-CD can provide an efficient method of maintaining postharvest quality and extending the shelf life of bananas.

The Role of Cations in Resorcinol–Formaldehyde Gel Textural Characteristics

The production of resorcinol–formaldehyde xerogels has yielded insight into the gelation processes underpinning their structures. In this work, the role of the cation species from the catalyst is probed by studying the simultaneous addition of sodium carbonate and calcium carbonate to a resorcinol–formaldehyde mixture. Twenty-eight xerogels were prepared by varying the solids content, catalyst concentration, and catalyst composition, and each was analysed for its textural properties, including the surface area and average pore diameter. The results indicate that the role of the cation is linked to the stabilisation of the clusters formed within the system, and that the Group II catalyst causes the salting out of the oligomers, resulting in fewer, larger clusters, hence, an increase in pore size and a broadening of the pore size distribution. The results provide insight into how these systems can be further controlled to create tailored porous materials for a range of applications.

Curcuminoid Co-Loading Platinum Heparin-Poloxamer P403 Nanogel Increasing Effectiveness in Antitumor Activity

Nanosized multi-drug delivery systems provide synergistic effects between drugs and bioactive compounds, resulting in increased overall efficiency and restricted side effects compared to conventional single-drug chemotherapy. In this study, we develop an amphiphilic heparin-poloxamer P403 (HP403) nanogel that could effectively co-load curcuminoid (Cur) and cisplatin hydrate (CisOH) (HP403@CisOH@Cur) via two loading mechanisms. The HP403 nanogels and HP403@CisOH@Cur nanogels were closely analyzed with 1H-NMR spectroscopy, FT-IR spectroscopy, TEM, and DLS, exhibiting high stability in spherical forms. In drug release profiles, accelerated behavior of Cur and CisOH at pH 5.5 compared with neutral pH was observed, suggesting effective delivery of the compounds in tumor sites. In vitro studies showed high antitumor activity of HP403@CisOH@Cur nanogels, while in vivo assays showed that the dual-drug platform prolonged the survival time of mice and prevented tail necrosis. In summary, HP403@CisOH@Cur offers an intriguing strategy to achieve the cisplatin and curcumin synergistic effect in a well-designed delivery platform that increases antitumor effectiveness and overcomes undesired consequences caused by cisplatin in breast cancer treatment.

Self-Gelling Solid Lipid Nanoparticle Hydrogel Containing Simvastatin as Suitable Wound Dressing: An Investigative Study

Hydrogels, an advanced interactive system, is finding use as wound dressings, however, they exhibit restricted mechanical properties, macroscopic nature, and may not manage high exudate wounds or incorporate lipophilic actives. In this study, we developed a self-gelling solid lipid nanoparticle (SLNs) dressing to incorporate simvastatin (SIM), a lipophilic, potential wound-healing agent, clinically limited due to poor solubility (0.03 mg/mL) and absorption. The study explores unconventional and novel application of SIM. The idea was to incorporate a significant amount of SIM in a soluble form and release it slowly over a prolonged time. Further, a suitable polymeric surfactant was selected that assigned a self-gelling property to SLNs (SLN-hydrogel) so as to be used as a novel wound dressing. SLNs assign porosity, elasticity, and occlusivity to the dressing to keep the wound area moist. It will also provide better tolerance and sensory properties to the hydrogel. SIM loaded SLN-hydrogel was prepared employing an industry amenable high-pressure homogenization technique. The unique hydrogel dressing was characterized for particle size, zeta potential, Fourier transform infra-red spectroscopy, powder X-ray diffraction, differential scanning calorimetry, rheology, and texture. Significant loading of SIM (10% w/w) was achieved in spherical nanoparticule hydrogel (0.3 nm (nanoparticles) to2 µm (gelled-matrix)) that exhibited good spreadability and mechanical properties and slow release up to 72 h. SLN-hydrogel was safe as per the organization for economic co-operation and development (OECD-404) guidelines, with no signs of irritation. Complete healing of excision wound observed in rats within 11 days was 10 times better than marketed povidone-iodine product. The presented work is novel both in terms of classifying a per se SLN-hydrogel and employing SIM. Further, it was established to be a safe, effective, and industry amenable invention.

Effects of Sulfate and Sulfuric Acid on Efficiency of Geopolymers as Concrete Repair Materials

Various geopolymer mortars (GPMs) as concrete repairing materials have become effective owing to their eco-friendly properties. Geopolymer binders designed from agricultural and industrial wastes display interesting and useful mechanical performance. Based on this fact, this research (experimental) focuses on the feasibility of achieving a new GPM with improved mechanical properties and enhanced durability performance against the aggressive sulfuric acid and sulfate attacks. This new ternary blend of GPMs can be achieved by combining waste ceramic tiles (WCT), fly ash (FA) and ground blast furnace slag (GBFS) with appropriate proportions. These GPMs were designed from a high volume of WCT, FA, and GBFS to repair the damaged concretes existing in the construction sectors. Flexural strength, slant shear bond strength, and compatibility of the obtained GPMs were compared with the base or normal concrete (NC) before and after exposure to the aggressive environments. Tests including flexural four-point loading and thermal expansion coefficient were performed. These GPMs were prepared using a low concentration of alkaline activator solution with increasing levels of GBFS and FA replaced by WCT. The results showed that substitution of GBFS and FA by WCT in the GPMs could enhance their bond strength, mechanical characteristics, and durability performance when exposed to aggressive environments. In addition, with the increase in WCT contents from 50 to 70%, the bond strength performance of the GPMs was considerably enhanced under sulfuric acid and sulfate attack. The achieved GPMs were shown to be highly compatible with the concrete substrate and excellent binders for various civil engineering construction applications. It is affirmed that the proposed GPMs can efficiently be used as high-performance materials to repair damaged concrete surfaces.

Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals

Herein we report the synthesis of cellulose-based metal-loaded nano-sponges and their application as heterogeneous catalysts in organic synthesis. First, the combination in water solution of TEMPO-oxidized cellulose nanofibers (TOCNF) with branched polyethyleneimine (bPEI) and citric acid (CA), and the thermal treatment of the resulting hydrogel, leads to the synthesis of an eco-safe micro- and nano-porous cellulose nano-sponge (CNS). Subsequently, by exploiting the metal chelation characteristics of CNS, already extensively investigated in the field of environmental decontamination, this material is successfully loaded with Cu (II) or Zn (II) metal ions. Efficiency and homogeneity of metal-loading is confirmed by scanning electron microscopy (SEM) analysis with an energy dispersive X-ray spectroscopy (EDS) detector and by inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The resulting materials perform superbly as heterogeneous catalysts for promoting the reaction between aromatic aldehydes and alcohols in the synthesis of aromatic acetals, which play a fundamental role as intermediates in organic synthesis. Optimized conditions allow one to obtain conversions higher than 90% and almost complete selectivity toward acetal products, minimizing, and in some cases eliminating, the formation of carboxylic acid by-products. ICP-OES analysis of the reaction medium allows one to exclude any possible metal-ion release, confirming that catalysis undergoes under heterogeneous conditions. The new metal-loaded CNS can be re-used and recycled five times without losing their catalytic activity.

Mechanically Strong and Tailorable Polyimide Aerogels Prepared with Novel Silicone Polymer Crosslinkers

Polyimide (PI) aerogels were prepared using self-designed silicone polymer cross-linkers with multi-amino from low-cost silane coupling agents to replace conventional small-molecule cross-linkers. The long-chain structure of silicone polymers provides more crosslinking points than small-molecule cross-linkers, thus improving the mechanical properties of polyimide. To investigate the effects of amino content and degree of polymerization on the properties of silicone polymers, the different silicone polymers and their cross-linked PI aerogels were prepared. The obtained PI aerogels exhibit densities as low as 0.106 g/cm3 and specific surface areas as high as 314 m2/g, and the maximum Young’s modulus of aerogel is up to 20.9 MPa when using (T-20) as cross-linkers. The cross-linkers were an alternative to expensive small molecule cross-linkers, which can improve the mechanical properties and reduce the cost of PI aerogels.

Synthesis and Characterization of Carboxymethyl Chitosan Nanosponges with Cyclodextrin Blends for Drug Solubility Improvement

This study aimed to enhance the solubility and release characteristics of docetaxel by synthesizing highly porous and stimuli responsive nanosponges, a nano-version of hydrogels with the additional qualities of both hydrogels and nano-systems. Nanosponges were prepared by the free radical polymerization technique and characterized by their solubilization efficiency, swelling studies, sol-gel studies, percentage entrapment efficiency, drug loading, FTIR, PXRD, TGA, DSC, SEM, zeta sizer and in vitro dissolution studies. In vivo toxicity study was conducted to assess the safety of the oral administration of prepared nanosponges. FTIR, TGA and DSC studies confirmed the successful grafting of components into the stable nano-polymeric network. A porous and sponge-like structure was visualized through SEM images. The particle size of the optimized formulation was observed in the range of 195 ± 3 nm. The fabricated nanosponges noticeably enhanced the drug loading and solubilization efficiency of docetaxel in aqueous media. The drug release of fabricated nanosponges was significantly higher at pH 6.8 as compared to pH 1.2 and 4.5. An acute oral toxicity study endorsed the safety of the system. Due to an efficient preparation technique, as well as its enhanced solubility, excellent physicochemical properties, improved dissolution and non-toxic nature, nanosponges could be an efficient and a promising approach for the oral delivery of poorly soluble drugs.

GOx/Hb Cascade Oxidized Crosslinking of Silk Fibroin for Tissue-Responsive Wound Repair

Promising wound dressings can achieve rapid soft-tissue filling while refactoring the biochemical and biophysical microenvironment to recruit endogenous cells, facilitating tissue healing, integration, and regeneration. In this study, a tissue biomolecule-responsive hydrogel matrix, employing natural silk fibroin (SF) as a functional biopolymer and haemoglobin (Hb) as a peroxidase-like biocatalyst, was fabricated through cascade enzymatic crosslinking. The hydrogels possessed mechanical tunability and displayed adjustable gelation times. A tyrosine unit on SF stabilised the structure of Hb during the cascade oxidation process; thus, the immobilized Hb in SF hydrogels exhibited higher biocatalytic efficiency than the free enzyme system, which provided a continuously antioxidative system. The regulation of the dual enzyme ratio endowed the hydrogels with favourable biocompatibility, biodegradability, and adhesion strength. These multifunctional hydrogels provided a three-dimensional porous extracellular matrix-like microenvironment for promoting cell adhesion and proliferation. A rat model with a full-thickness skin defect revealed accelerated wound regeneration via collagen deposition, re-epithelialisation and revascularisation. Enzyme-loaded hydrogels are an attractive and high-safety biofilling material with the potential for wound healing, tissue regeneration, and haemostasis.