Search Results (2,449)

Microneedles are of great interest in diverse fields, including cosmetics, drug delivery systems, chromatography, and biological sensing for disease diagnosis. Self-dissolving ultrafine microneedles of pure sodium hyaluronate hydrogels were fabricated using a UV-curing TiO₂-SiO₂ gas-permeable mold polymerized by sol-gel hydrolysis reactions in nanoimprint lithography processes under refrigeration at 5 °C, where thermal decomposition of microneedle components can be avoided. The moldability, strength, and dissolution behavior of sodium hyaluronate hydrogels with different molecular weights were compared to evaluate the suitability of ultrafine microneedles with a bottom diameter of 40 μm and a height of 80 μm. The appropriate molecular weight range and formulation of pure sodium hyaluronate hydrogels were found to control the dissolution behavior of self-dissolving ultrafine microneedles while maintaining the moldability and strength of the microneedles. This fabrication technology of ultrafine microneedles expands their possibilities as a next-generation technique for bioactive gels for controlling the blood levels of drugs and avoiding pain during administration. Full article

Continuous worldwide demands for more clean energy urge researchers and engineers to seek various energy applications, including electrocatalytic processes. Traditional energy-active materials, when combined with conducting materials and non-active polymeric materials, inadvertently leading to reduced interaction between their active and conducting components. This results in a drop in active catalytic sites, sluggish kinetics, and compromised mass and electronic transport properties. Furthermore, interaction between these materials could increase degradation products, impeding the efficiency of the catalytic process. Gels appears to be promising candidates to solve these challenges due to their larger specific surface area, three-dimensional hierarchical accommodative porous frameworks for active particles, self-catalytic properties, tunable electronic and electrochemical properties, as well as their inherent stability and cost-effectiveness. This review delves into the strategic design of catalytic gel materials, focusing on their potential in advanced energy conversion and storage technologies. Specific attention is given to catalytic gel material design strategies, exploring fundamental catalytic approaches for energy conversion processes such as the CO₂ reduction reaction (CO₂RR), oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and more. This comprehensive review not only addresses current developments but also outlines future research strategies and challenges in the field. Moreover, it provides guidance on overcoming these challenges, ensuring a holistic understanding of catalytic gel materials and their role in advancing energy conversion and storage technologies. Full article

Millions of people worldwide suffer from low back pain and disability associated with intervertebral disc (IVD) degeneration. IVD degeneration is highly correlated with aging, as the nucleus pulposus (NP) dehydrates and the annulus fibrosus (AF) fissures form, which often results in intervertebral disc herniation or disc space collapse and related clinical symptoms. Currently available options for treating intervertebral disc degeneration are symptoms control with therapy modalities, and/or medication, and/or surgical resection of the IVD with or without spinal fusion. As such, there is an urgent clinical demand for more effective disease-modifying treatments for this ubiquitous disorder, rather than the current paradigms focused only on symptom control. Hydrogels are unique biomaterials that have a variety of distinctive qualities, including (but not limited to) biocompatibility, highly adjustable mechanical characteristics, and most importantly, the capacity to absorb and retain water in a manner like that of native human nucleus pulposus tissue. In recent years, various hydrogels have been investigated in vitro and in vivo for the repair of intervertebral discs, some of which are ready for clinical testing. In this review, we summarize the latest findings and developments in the application of hydrogel technology for the repair and regeneration of intervertebral discs. Full article

In recent years, stimuli-responsive nanogels that can undergo suitable transitions under endogenous (e.g., pH, enzymes and reduction) or exogenous stimuli (e.g., temperature, light, and magnetic fields) for on-demand drug delivery, have received significant interest in biomedical fields, including drug delivery, tissue engineering, wound healing, and gene therapy due to their unique environment-sensitive properties. Furthermore, these nanogels have become very popular due to some of their special properties such as good hydrophilicity, high drug loading efficiency, flexibility, and excellent biocompatibility and biodegradability. In this article, the authors discuss current developments in the synthesis, properties, and biomedical applications of stimulus-responsive nanogels. In addition, the opportunities and challenges of nanogels for biomedical applications are also briefly predicted. Full article

The development of new and effective antibacterials for pharmaceutical or cosmetic skin care that have a low potential for the emergence and expansion of bacterial resistance is of high demand in scientific and applied research. Great hopes are placed on alternative agents such as bactericidal peptidoglycan hydrolases, depolymerases, etc. Enzybiotic-based preparations are being studied for the treatment of various infections and, among others, can be used as topical formulations and dressings with protein-polysaccharide complexes. Here, we investigate the antibiofilm properties of a novel enzybiotic cocktail of phage endolysin LysSi3 and bacteriocin lysostaphin, formulated in the alginate gel matrix and its ability to control the opportunistic skin-colonizing bacteria Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, as well as mixed-species biofilms. Our results propose that the application of SiL-gel affects different components of biofilm extracellular polymeric substances, disrupts the matrix, and eliminates the bacteria embedded in it. This composition is highly effective against biofilms composed of Gram-negative and Gram-positive species and does not possess significant cytotoxic effects. Our data form the basis for the development of antibacterial skin care products with a gentle but effective mode of action. Full article

Rapid extraction and concentration systems based on green materials such as cellulose or lignin are promising. However, there is still a need to optimize the material properties and production processes. Unlike conventional cellulose or lignin sorbent materials, aquatic reed root cells can concentrate external organic pollutants in the water and accumulate them in the plant. Inspired by this, a new nanocellulose–lignin aerogel (NLAG) was designed, in which nanocellulose was used as a substrate and lignin and polyamide epoxy chloropropane were used to crosslink cellulose in order to enhance the strength of the NLGA, resulting in good mechanical stability and water–oil amphiphilic properties. In practical applications, the organic membrane on the NLAG can transport organic pollutants from water to the NLAG, where they are immobilized. This is evidenced by the fact that the aerogel can remove more than 93% of exogenous phenol within a few minutes, highly enriching it inside. In addition, the aerogel facilitates filtration and shape recovery for reuse. This work establishes a novel biopolymer–aerogel-based extraction system with the advantages of sustainability, high efficiency, stability, and easy detachability, which are hard for the traditional adsorbent materials to attain. Full article

Allantoin possesses numerous beneficial properties for the skin, like anti-irritant effects, wound healing, skin hydration, and epithelization. In this paper, we investigated a suitable preparation method for an allantoin hydrogel using the Semi-Solid Control Diagram (SSCD) method and characterized its rheological and consistency behavior. To accomplish this, xanthan gum (XG) was selected as a model gelling agent. Briefly, four hydrogels were prepared, two without allantoin (coded M01 and M02) and two with allantoin (M1 and M2). Similarly, the formulations were either prepared through magnetic stirring (M01 and M1) or homogenization in a mortar (M02 and M2). The prepared hydrogels were evaluated using the SSCD for specific parameters and indexes. The Good Quality Index (GQI) shows a higher value for the formulation, M1 = 6.27, compared to M2 = 5.45. This result is also underlined by the value of M01 = 6.45, which is higher than M02 = 6.38. Considering the consistency, the formulation M01 possessed the highest spreadability, followed by M02 and then the allantoin hydrogels M1 and M2. The rheological behavior had a thixotropic pseudoplastic flow for all the formulations. The use of SSCD pictographs outlined the rheological properties that need improvement, the method that is suitable to prepare the allantoin hydrogels, and the influence of the allantoin suspended in the XG hydrogel. Full article

The application of principal component analysis (PCA) as an unsupervised learning method has been used in uncovering correlations among diverse features of aerogel-based electrocatalysts. This analytical approach facilitates a comprehensive exploration of catalytic activity, revealing intricate relationships with various physical and electrochemical properties. The first two principal components (PCs), collectively capturing nearly 70% of the total variance, attested the reliability and efficacy of PCA in unveiling meaningful patterns. This study challenges the conventional understanding that a material’s reactivity is solely dictated by the quantity of catalyst loaded. Instead, it unveils a complex perspective, highlighting that reactivity is intricately influenced by the material’s overall design and structure. The PCA bi-plot uncovers correlations between pH and Tafel slope, suggesting an interdependence between these variables and providing valuable insights into the complex interactions among physical and electrochemical properties. Tafel slope stands to be positively correlated with PC₁ and PC₂, showing an evident positive correlation with the pH. These findings showed that the pH can have a positive correlation with the Tafel slope, however, it does not necessarily reflect a direct positive correlation with the overpotential. The impact of pH on current density (j)and Tafel slope underscores the importance of adjusting pH to lower overpotential effectively, enhancing catalytic activity. Surface area (from 30 to 533 m² g⁻¹) emerges as a key physical property, inclusively inverse correlation with overpotential, indicating its direct role in lowering overpotential and increasing catalytic activity. The introduction of PC₃, in conjunction with PC₁, enriches the analysis by revealing consistent trends despite a slightly lower variance (60%). This reinforces the robustness of PCA in delineating distinct characteristics of graphene aerogels, affirming their potential implications in diverse electrocatalytic applications. In summary, PCA proves to be a valuable tool for unraveling complex relationships within aerogel-based electrocatalysts, extending insights beyond catalytic sites to emphasize the broader spectrum of material properties. This approach enhances comprehension of dataset intricacies and holds promise for guiding the development of more effective and versatile electrocatalytic materials. Full article

In the field of cultural heritage, the use of natural gels is rising for the application of active agents. Here, two natural polymers are assessed: agar, a pioneer hydrogel for conservation treatments, and chitosan, a rather novel and metal-binding gel. For chitosan, a state-of-the-art based formulation (CS–ItA–LCys) is evaluated as it was reported for silver-complexing properties. It is evaluated whether these polymers can withstand the addition of the chelating compound deferoxamine, which is a bacterial siderophore. This allows for the obtainment of completely bio-sourced gel systems. A Fourier-transformed (FT) infrared spectroscopy characterization is performed, completed with rheological measurements and Cryo-Scanning Electron Microscopy (cryo–SEM) to investigate the physico–chemical properties of the gels, as well as their interaction with deferoxamine. Both polymers are also tested for their inherent complexing ability on silver ions using FT–Raman spectroscopy. A multi-analytical comparison shows different microstructures, in particular, the presence of a thick membrane for chitosan and different mechanical behaviors, with agar being more brittle. Neither hydrogel seems affected by the addition of deferoxamine; this is shown by similar rheological behavior and molecular structures in the presence or absence of the chelator. The intrinsic abilities of the chitosan formulation to make silver complex are demonstrated with the observation of two peaks characteristic of Ag–S and Ag–O bonds. Agar and chitosan are both proven to be reliable gels to act as carriers for bio-based active agents. This paper confirms the potential asset of the chitosan formulation CS–ItA–LCys as a promising gel for the complexation of soluble silver. Full article

Most studies have focused on complex strategies for materials preparation instead of industrial wastewater treatment due to emergency treatment requirements for metal pollution. This study evaluated sodium polyacrylate (PSA) as a carbon skeleton and FeS as a functional material to synthesize PSA-nFeS material. The characteristics and interactions of PSA-nFeS composites treated with hexavalent chromium were analyzed by means of various techniques, such as scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FTIR), and atomic absorption spectroscopy (AAS). Adsorption-coupled reduction was observed to be the predominant mechanism of Cr(VI) removal. The feasibility of PSA-nFeS composites in reducing toxicity and removing of Cr(VI) from real effluents was investigated through column studies and material properties evaluation. The continuous column studies were conducted using tannery effluents to optimize feed flow rates, initial feed Cr(VI) concentration, and column bed height. The results revealed that PSA-nFeS composites are ideal for filling materials in portable filtration devices due to their lightweight and compact size. Full article

During the last decades, salicylic acid (SA) and hyaluronic acid (HA) have been studied for a wide range of cosmetic and pharmaceutical applications. The current study investigated the drug loading potential of SA in HA-based crosslinked hydrogel films using a post-loading (osmosis) method of the unmedicated xerogels from saturated aqueous solutions of salicylic acid over a range of pH values. The films were characterized with Fourier-transform infra-red spectroscopy (FT-IR) and ultraviolet-visible (UV-Vis) spectrophotometry in order to elucidate the drug loading profile and the films’ integrity during the loading process. Additional studies on their weight loss (%), gel fraction (%), thickness increase (%) and swelling (%) were performed. Overall, the studies showed significant film disintegration at highly acidic and basic solutions. No drug loading occurred at neutral and basic pH, possibly due to the anionic repulsion between SA and HA, whereas at, pH 2.1, the drug loading was promising and could be detected via UV-Vis analysis of the medicated solutions, with the SA concentration in the xerogel films at 28% w/w. Full article

The electro-Fenton process is based on the generation of hydroxyl radicals (OH•) from hydroxide peroxide (H₂O₂) generated in situ by an oxygen reduction reaction (ORR). Catalysts based on carbon gels have aroused the interest of researchers as ORR catalysts due to their textural, chemical and even electrical properties. In this work, we synthesized metal-free electrocatalysts based on carbon gels doped with graphene oxide, which were conformed to a working electrode. The catalysts were prepared from organic-gel-based inks using painted (brush) and screen-printed methods free of binders. These new methods of electrode preparation were compared with the conventional pasted method on graphite supports using a binder. All these materials were tested for the electro-Fenton degradation of amoxicillin using a homemade magnetite coated with carbon (Fe₃O₄/C) as a Fenton catalyst. All catalysts showed very good behavior, but the one prepared by ink painting (brush) was the best one. The degradation of amoxicillin was close to 90% under optimal conditions ([Fe₃O₄/C] = 100 mg L⁻¹, −0.55 V) with the catalyst prepared using the painted method with a brush, which had 14.59 mA cm⁻² as J_K and a H₂O₂ electrogeneration close to 100% at the optimal voltage. These results show that carbon-gel-based electrocatalysts are not only very good at this type of application but can be adhered to graphite free of binders, thus enhancing all their catalytic properties. Full article

Natural polymers, such as alginate and chitosan, are widely exploited for drug delivery applications due to their biocompatibility, low toxicity, and sustainable sourcing. In this study, pH-responsive gel microspheres were fabricated from an alginate/Ozoile emulsion. Ozoile (Stable Ozonides) is a biological inducer, derived from olive oil, which stimulates the endogenous defense system by promoting the repair of tissue damage and restoration of proper physiology through the regulation of gene transcription. Here, the versatile and cost-effective electrospray technique without the use of organic solvents was used to fabricate alginate/Ozoile microspheres with high throughput. The process parameters (voltage, flow rate, and needle gauge) were optimized to obtain microspheres with good sphericity factor and tailored diameter (250–700 μm). The microspheres were additionally optimized through a chitosan coating to enhance their stability and regulate the gel matrix’s degradation process. Morphological analysis, FTIR spectroscopy, and degradation tests confirmed the structural integrity and pH-responsive behavior of the gel microspheres. This research offers a promising route for targeted drug delivery systems, particularly in applications related to the modulation of oxidative stress and management of inflammation. Full article

Yam (Dioscorea. sp.) is an edible starchy tuber with potential for being a commercial source of starch for industrial purposes, but yam starch is underutilized. The dynamic oscillatory and thermal properties of yam starches from sixteen varieties each of Dioscorea. rotundata, Dioscora. alata, Dioscorea. bulbifera and one variety of Dioscorea. dumetorum from Nigeria were studied to determine their potential for industrial utilization. The storage modulus, loss modulus, damping factor and complex viscosity as a function of frequency (ω) of the dioscorea gels, as well as the onset temperature (T_o), peak gelatinization temperature (T_p), end of gelatinization (T_C), and gelatinization enthalpy of the starches were determined by standard procedures. Results showed that all the dioscorea starches showed a typical elastic behavior with the magnitude of G′ greater than G″ while tan δ < 1 in all varieties. Thus, the starch gels were more elastic than viscous. All the starch gels exhibited shear thinning characteristics and showed frequency (ω) independence characteristics of weak gels. D. rotundata varieties had the lowest ∆H_gel, while D. bulbifera varieties had the highest. The diversity of the visco-elastic and thermal properties of the yam starch gels from different varieties and species can be an advantage in their utilization in both food and non-food industries. Full article