Three-dimensional Polymeric Network Research Articles

Real-Space Visualization of Charged Polymer Network of Hydrogel by Double Network Strategy and Mineral Staining.

Hydrogels consist of three-dimensional (3D) and complicated polymer networks that determine their physical properties. Among the methods for structural analyses of hydrogels, the real-space imaging of a polymer network of hydrogels on a nanometer scale is one of the optimal methods; however, it is highly challenging. In this study, we propose a direct observation method for cationic polymer networks using transmission electron microscopy (TEM). By combining the double network strategy and the mineral staining technique, we overcame the challenges of polymer aggregation and the low electron density of the polymer. An objective cationic network was incorporated into a neutral skeleton network to suppress shrinkage during subsequent staining. Titania mineralization along the cationic polymer strands provided sufficient electron density for the objective polymer network for TEM observation. This observation method enables the visualization of local structures in real space and plays a complementary role to scattering methods for soft matter structure analysis.

Revolutionizing medicine: Molecularly imprinted polymers as precision tools in cancer diagnosis and antibiotic detection.

Molecularly imprinted polymers (MIPs) are pivotal in medicine, mimicking biological receptors with enhanced specificity and affinity. Comprising templates, functional monomers, and cross-linkers, MIPs form stable three-dimensional polymer networks. Synthetic templates like glycan and aptamers improve efficiency, guiding the molecular imprinting process. Cross-linking determines MIPs' morphology and mechanical stability, with printable hydrogels offering biocompatibility and customizable properties, mimicking native extracellular matrix (ECM) microenvironments. Their versatility finds applications in tissue engineering, soft robotics, regenerative medicine, and wastewater treatment. In cancer research, MIPs excel in both detection and therapy. MIP-based detection systems exhibit superior sensitivity and selectivity for cancer biomarkers. They target nucleic acids, proteins, and exosomes, providing stability, sensitivity, and adaptability. In therapy, MIPs offer solutions to challenges like multidrug resistance, excelling in drug delivery, photodynamic therapy, photothermal therapy, and biological activity regulation. In microbiology, MIPs serve as adsorbents in solid-phase extraction (SPE), efficiently separating and enriching antibiotics during sample preparation. They contribute to bacterial identification, selectively capturing specific strains or species. MIPs aid in detecting antibiotic residues using fluorescent nanostructures and developing sensors for sulfadiazine detection in food samples. In summary, MIPs play a pivotal role in advancing medical technologies with enhanced sensitivity, selectivity, and versatility. Applications range from biomarker detection to innovative cancer therapies, making MIPs indispensable for the accurate determination and monitoring of diverse biological and environmental samples.

Stereoscopic Polymer Network for Developing Mechanically Robust Flexible Perovskite Solar Cells with an Efficiency Approaching 25.

Flexible perovskite solar cells (pero-SCs) have the potential to overturn the application scenario of silicon photovoltaic technology. However, their mechanical instability severely impedes their practical applicability, and the corresponding intrinsic degradation mechanism remains unclear. In this study, the degradation behavior of flexible pero-SCs is systematically analyzed under mechanical stress and it is observed that the structural failure first occurs in the polycrystal perovskite film, then extend to interfaces. To suppress the structural failure, pentaerythritol triacrylate, a crosslinked molecule with three stereoscopic crosslink sites, is employed to establish a 3D polymer network in both the interface and bulk perovskite. This network reduced the Young's modulus of the perovskite and simultaneously enhanced the interfacial toughness. As a result, the formation of cracks and delamination, which occur under a high mechanical stress, is significantly suppressed in the flexible pero-SC, which consequently retained 92% of its initial power conversion efficiency (PCE) after 20000 bending cycles. Notably, the flexible device also shows a record PCE of 24.9% (certified 24.48%).

Hydrogel-Based Therapy for Age-Related Macular Degeneration: Current Innovations, Impediments, and Future Perspectives.

Age-related macular degeneration (AMD) is an ocular disease that leads to progressive photoreceptor death and visual impairment. Currently, the most common therapeutic strategy is to deliver anti-vascular endothelial growth factor (anti-VEGF) agents into the eyes of patients with wet AMD. However, this treatment method requires repeated injections, which potentially results in surgical complications and unwanted side effects for patients. An effective therapeutic approach for dry AMD also remains elusive. Therefore, there is a surge of enthusiasm for the developing the biodegradable drug delivery systems with sustained release capability and develop a promising therapeutic strategy. Notably, the strides made in hydrogels which possess intricate three-dimensional polymer networks have profoundly facilitated the treatments of AMD. Researchers have established diverse hydrogel-based delivery systems with marvelous biocompatibility and efficacy. Advantageously, these hydrogel-based transplantation therapies provide promising opportunities for vision restoration. Herein, we provide an overview of the properties and potential of hydrogels for ocular delivery. We introduce recent advances in the utilization of hydrogels for the delivery of anti-VEGF and in cell implantation. Further refinements of these findings would lay the basis for developing more rational and curative therapies for AMD.

Biopolymer Packaging Materials in the Pharmaceutical Industry

Biopolymer packaging materials are gaining prominence in the pharmaceutical industry due to environmental concerns. Derived from renewable sources, these biopolymers offer biodegradability, biocompatibility, and non-toxicity, making them ideal for various pharmaceutical applications. In drug delivery, biopolymers play a crucial role in controlled release formulations, especially for personalized medicines and biopharmaceutical products. Hydrogels, three-dimensional polymer networks, are key in mimicking living tissues and facilitating stimuli-responsive drug release with minimal toxic effects. The formulation strategies involve diffusion-controlled, degradation-controlled, or environmentally triggered release. Biodegradable systems, using polymers like poly(lactic acid) and poly(glycolic acid), contribute to sustainable drug delivery by undergoing controlled degradation. Osmotic delivery systems leverage osmotic pressure for controlled drug release, while stimuli-responsive designs respond to environmental changes. Biopolymer integration in pharmaceutical packaging aligns with eco-friendly practices, addressing challenges posed by traditional petroleum-based materials. This shift signifies a sustainable and innovative approach to pharmaceutical packaging in harmony with environmental preservation.

In Situ Single-Cell Bacterial Imaging Provides Mechanistic Insight into the Photodynamic Action of Photosensitizer-Loaded Hydrogels.

Hydrogels, three-dimensional hydrophilic polymeric networks with high water retaining capacity, have gained prominence in wound management and drug delivery due to their tunability, softness, permeability, and biocompatibility. Electron-beam polymerized poly(ethylene glycol) diacrylate (PEGDA) hydrogels are particularly useful for phototherapies such as antimicrobial photodynamic therapy (aPDT) due to their excellent optical properties. This work takes advantage of the transparency of PEGDA hydrogels to investigate bacterial responses to aPDT at the single-cell level, in real-time and in situ. The photosensitizer methylene blue (MB) was loaded in PEGDA hydrogels by using two methods: reversible loading and irreversible immobilization within the 3D polymer network. MB release kinetics and singlet oxygen generation were studied, revealing the distinct behaviors of both hydrogels. Real-time imaging of Escherichia coli was conducted during aPDT in both hydrogel types, using the Min protein system to report changes in bacterial physiology. Min oscillation patterns provided mechanistic insights into bacterial photoinactivation, revealing a dependence on the hydrogel preparation method. This difference was attributed to the mobility of MB within the hydrogel, affecting its direct interaction with bacterial membranes. These findings shed light on the complex interplay between hydrogel properties and the bacterial response during aPDT, offering valuable insights for the development of antibacterial wound dressing materials. The study demonstrates the capability of real-time, single-cell fluorescence microscopy to unravel dynamic bacterial behaviors in the intricate environment of hydrogel surfaces during aPDT.

The evolution of artificial tears based on hyaluronic acid

In recent years, there has been growing interest in the use of tear substitutes, based on natural polysaccharides in the treatment of dry eye syndrome, the leader of which is hyaluronic acid (HA). It has sufficient biocompatibility, non-immunogenicity, high viscoelasticity, hydrophilic, mucus-adhesive and good moisturizing properties. At the same time, in order to improve artificial tear preparations, there is a need to improve the mechanical and rheological properties of HA, its hygroscopicity, swelling in an aqueous environment and reducing the rate of biodegradation. One of the ways to solve this problem was the chemical modification of HA, by cross-linking its chains with two or more covalent bonds, with the participation of various polyfunctional molecules: urea, HA-cysteine ethyl ester, polyfunctional diepoxides, glutaraldehyde, carbodiimide, and many others. At the same time, the rigidity of the three-dimensional polymer network increases, increasing its resistance to enzymatic decomposition at the site of burial. Cross-linked HA has a higher viscosity compared to native hyaluronic acid due to the binding of its chains, which determines longer retention on the corneal epithelium and naturally makes it possible to reduce the frequency of drug instillations. Convincing data were obtained on the effectiveness of the resulting cross-linked hydrogel with non-Newtonian properties in vitro – on cultures of corneal epithelial cells and in vivo – on models of mechanical trauma and chemical burns of the cornea, as well as in animals with torpid corneal ulcers. The clinical effectiveness of cross-linked hyaluronic acid in the treatment of patients with dry eye syndrome of varying severity, including those due to Sjögren’s syndrome, has also been established. The higher effectiveness of cross-linked HA compared to native HA preparations has been convincingly proven. Taking into account the available information, an official drug has been developed based on cross-linked 0.2% hyaluronic acid Ocutears® Hydro+ (Santen).

Mechanical properties and microstructure of waterborne polyurethane-modified cement composites as concrete repair mortar

With the increase in service life, the durability of a large number of concrete structures deteriorates year by year under the influence of the external environment, requiring urgent repair and reinforcement. Ordinary cement concrete materials have disadvantages such as high brittleness, low tensile strength, poor bonding ability, and insufficient durability, making it difficult to meet the repair needs of high-quality building structures. Therefore, self-synthesized anion WPU was used to study its effect on the mechanical properties of cement-based repair mortar. The research found that waterborne polyurethane (WPU)-modified cementitious composite repair materials exhibit better bonding strength with old concrete substrates compared to traditional cement-based materials. Additionally, the incorporation of WPU significantly reduces the brittleness of the repair material, ensuring enhanced efficiency in the repair process. However, according to the hydration heat test results, the addition of WPU delays the hydration process of the composite repair materials. In addition, the addition of WPU enhances the flexibility and bonding ability of the materials, with flexural strength and tensile strength at the age of 28 days reaching 13 MPa and 6 MPa, respectively. Through stress‒strain curve analysis, it was found that the maximum strain amplification of WPU cement mortar can reach 134 %. Combined with SEM testing, it was observed that cured WPU films were present in specimens aged 28 days with P/C ratios of 10 % and 15 %. WPU and cement hydration products permeate each other, forming a three-dimensional polymer network structure, improving the pore structure, and fully exerting the flexibility of WPU. This also validates the experimental results of increased ultimate tensile strain. WPU cement-based composite repair materials have higher bonding strength at a high P/C ratio (15 %), and WPU alone, used as an interface agent for pretreating the interface of old concrete, can improve the interface bonding strength, up to twice that of the group without the surface agent.

Investigating Solid-State Luminescent Properties of New Cadmium(II) and Lead(II) Oxamato-Based Coordination Polymers

Two novel coordination polymers were synthesized through the reaction of the Hpcpa2− ligand (H3pcpa = N-(4-carboxyphenyl)oxamic acid) with cadmium(II) and lead(II) metal ions, yielding [Cd2(Hpcpa)2(H2O)6]n⋅H2O (1) and [Pb(Hpcpa)(H2O)]n (2). Structural analysis by single-crystal X-ray diffraction revealed that 1 consists of one-dimensional zigzag polymeric chains, while 2 is a three-dimensional polymer network. Additionally, investigations of their optical properties were carried out in a comparative study involving the previously reported pcpa-based coordination polymers {[Zn(Hpcpa)(H2O)3]·0.5H2O}n and {[Gd2(Hpcpa)3(H2O)5]·H2O}n], called here as 3 and 4, respectively. Under 330 nm excitation wavelength, all compounds exhibited broad emission bands spanning from 350 to 650 nm. Particularly, 1 and 3 displayed notable external quantum yields of 15.4 and 12.8%, respectively, highlighting their potential in luminescent applications.

In Situ Thermal Cross-Linking of 9,9'-Spirobifluorene-Based Hole-Transporting Layer for Perovskite Solar Cells.

A novel 9,9'-spirobifluorene derivative bearing thermally cross-linkable vinyl groups (V1382) was developed as a hole-transporting material for perovskite solar cells (PSCs). After thermal cross-linking, a smooth and solvent-resistant three-dimensional (3D) polymeric network is formed such that orthogonal solvents are no longer needed to process subsequent layers. Copolymerizing V1382 with 4,4'-thiobisbenzenethiol (dithiol) lowers the cross-linking temperature to 103 °C via the facile thiol-ene "click" reaction. The effectiveness of the cross-linked V1382/dithiol was demonstrated both as a hole-transporting material in p-i-n and as an interlayer between the perovskite and the hole-transporting layer in n-i-p PSC devices. Both devices exhibit better power conversion efficiencies and operational stability than devices using conventional PTAA or Spiro-OMeTAD hole-transporting materials.

Cryogel Scaffolds for Tissue-Engineering: Advances and Challenges for Effective Bone and Cartilage Regeneration.

Critical-sized bone defects and articular cartilage injuries resulting from trauma, osteonecrosis, or age-related degeneration can be often non-healed by physiological repairing mechanisms, thus representing a relevant clinical issue due to a high epidemiological incidence rate. Novel tissue-engineering approaches have been proposed as an alternative to common clinical practices. This cutting-edge technology is based on the combination of three fundamental components, generally referred to as the tissue-engineering triad: autologous or allogenic cells, growth-stimulating factors, and a scaffold. Three-dimensional polymer networks are frequently used as scaffolds to allow cell proliferation and tissue regeneration. In particular, cryogels give promising results for this purpose, thanks to their peculiar properties. Cryogels are indeed characterized by an interconnected porous structure and a typical sponge-like behavior, which facilitate cellular infiltration and ingrowth. Their composition and the fabrication procedure can be appropriately tuned to obtain scaffolds that match the requirements of a specific tissue or organ to be regenerated. These features make cryogels interesting and promising scaffolds for the regeneration of different tissues, including those characterized by very complex mechanical and physical properties, such as bones and joints. In this review, state-of-the-art fabrication and employment of cryogels for supporting effective osteogenic or chondrogenic differentiation to allow for the regeneration of functional tissues is reported. Current progress and challenges for the implementation of this technology in clinical practice are also highlighted.

Enhancing rheological and aging performance of matrix asphalt through thermoplastic phenol-formaldehyde resin-based intercalated clay nanocomposites: Mechanisms and effects

This research presents a comprehensive investigation into the development of advanced asphalt materials fortified with PF/OMMT nanocomposites, emphasizing the synergistic effects of melt blending and nano intercalation. Through meticulous characterization, including SEM, FT-IR, and XRD analyses, the study unveils the microstructural evolution, affirming the formation of highly oriented interlayer structures within the asphalt matrix. The incorporation of OMMT, known for its hydrophobicity, significantly enhances the interfacial interactions between PF and asphalt, thereby bolstering the material's mechanical resilience, specifically its tensile, shear, and high-temperature rutting resistance properties. The presence of PF imparts notable improvements in the asphalt's thermal stability and aging resistance, attributed to its inherent antioxidative properties and the establishment of a robust three-dimensional polymer network with OMMT. These advancements herald a promising avenue for the production of high-performance, durable asphalt with superior anti-aging characteristics, optimized for demanding environmental conditions and heavy-duty applications.

Preparation of composite coagulant for the removal of microplastics in water.

In this work, a composite flocculant (polyferric titanium sulfate-polydimethyldiallylammonium chloride [PFTS-PDMDAAC]) with a rich spatial network structure was prepared for the treatment of simulated wastewater containing polystyrene (PS) micro-nanoparticles. Characterization results showed that the surface of the PFTS-PDMDAAC was a three-dimensional network polymer of chain molecules that exhibited good thermal stability and formed an amorphous polymer containing multiply hydroxyl-bridged titanium and iron. When n(OH- ):n(Fe) = 1:2, n(PO4 3- ):n(Fe) = 0.35, n(Ti):n(Fe) = 1:8, n(DMDAAC):n(Fe) = 5:100, and the polymerization temperature is 60°C, the prepared composite flocculant has the best effect. The effects of dosage, pH, and agitation intensity on the flocculation properties of PFTS-PDMDAAC were also studied. The optimal removal rates of PS-μm and haze by PFTS-PDMDAAC were 85.60% and 90.10%, respectively, at a stirring intensity of 200 rpm, a pH of 9.0, and a PFTS-PDMDAAC dosage of 20 mg/L. The flocs produced by the PFTS-PDMDAAC flocculation were large and compact in structure, and the flocculation mechanism was mainly based on adsorption bridging. Kaolin played a promoting role in the process of PS-μm removal by PFTS-PDMDAAC floc and accelerated the formation of large and dense flocs. This study provided a reference for the coagulation method to remove micro-nanopollutants in the actual water treatment process. PRACTITIONER POINTS: A composite flocculant with rich spatial network structure (PFTS-PDMDAAC) was prepared. PFTS-PDMDAAC can effectively remove micro-nano polystyrene (PS) in wastewater. The floc produced by PFTS-PDMDAAC is large and compact in structure. The flocculation mechanism of PFTS-PDMDAAC is mainly adsorption bridging.

Preparation of emulsions-filled sodium alginate hydrogel beads to enhance the anti-cancer activity of fangchinoline in vivo and in vitro

Fangchinoline (Fan) is a natural alkaloids compound with a series of remarkable bioactivity, but the poor aqueous solubility limits the clinical application. Emulsions (EM) systems are commonly used to encapsulate and deliver hydrophobic active compound to enhance the bioavailability. Hydrogel beads (HGB) are three-dimensional hydrophilic polymer networks, which are able to immobilize colloidal delivery systems, resulting to the enhanced stability and controlled release in the gastrointestinal tract. In order to give full play to the bilateral advantages of emulsion and hydrogel, Fan loaded EM-filled sodium alginate HGB (Fan@EM-HGB) were designed and prepared in this paper. The average size of Fan@EM was 121.6 ± 2.7 nm and the zeta potential was -17.7 ± 0.3 mV. Physicochemical characterization demonstrated that Fan was successfully encapsulated in HGB with entrapment efficiency of 93.98 % and drug loading of 5.18 mg/g. The released behavior of Fan@EM-HGB followed a pH-controlled mechanism that was consistent with the first-order model. In vitro activity research shown that Fan@EM-HGB could significantly promote the apoptosis of A549 cells, with IC50 value more than 2.37 times higher than that of Fan. The in vivo results indicated that Fan@EM-HGB had an obvious anti- cancer effect, and molecular mechanism shown that Fan@EM-HGB could promote tumor cell apoptosis by inhibiting the activation of the PI3K/Akt/mTOR signaling pathway. The above research results suggest that nanoemulsions-filled hydrogel beads have potential application in delivery system for hydrophobic composition.

PH dependent biocompatible room temperature covalent organic polymers for selective chemotherapeutic drug delivery

Covalent organic polymers (COP) are a special class of two-dimensional and three-dimensional cross-linked polymeric networks with repeating organic units. They are ideally suited for drug delivery applications because of their large surface area, porous nature, and tunable properties. Furan-2,5-dicarbohydrazide and 1,3,5-triformylbenzene were used to synthesize pH-responsive hydrazone-linked furan-based spherical COP(FRT-COP) at room temperature. The formulated FRT-COP were later stabilized using hyaluronic acid (HA) and then encapsulated anticancer drug doxorubicin (DOX), utilizing the porous structure of the synthesized COP. The newly developed FRT-COP have a pore size of 10 nm, and FRT-COP-DOX-HA exhibit drug loading capacity of 34.4 % and an encapsulation efficiency of 52.32 %. The 80 % viability of NIH 3T3 cells and 82.1 % viability of the CT2A cells, even at a higher concentration of 100 μg/mL of the carrier system, proves the outstanding biocompatibility of the carrier system for chemotherapeutic drug delivery administration. The FRT-COP-DOX-HA-treated NIH-3T3 normal cell line exhibits a viability of 80.59 % at a material concentration of 25 μg/mL. Furthermore, CT2A cancer cell lines show a viability of 33.1 % at a material concentration of 25 μg/mL. The in vivo results obtained from the experiments performed on male BALB/c nude mice also unequivocally demonstrated the exceptional suitability of the proposed drug delivery carrier system for antitumor chemotherapeutic drug administration.

Rheology and 3D printing of alginate bio-stabilized earth concrete

Driven by the need for sustainable construction solutions, there is renewed interest in earth-based materials. Biopolymer stabilizers can enhance the rheological and structural properties of these materials to facilitate their use in 3D printing. This research examined the influence of sodium alginate on the stability, particle interaction, rheology, and 3D printability of kaolinite, a commonly found clay in soils deemed suitable for construction. Findings revealed that sodium alginate could boost electrostatic interactions to enhance the stability of kaolinite suspensions. This rise in repulsive potential energy could reduce storage modulus and yield stress by orders of magnitude. However, as the alginate content increased beyond its critical overlapping concentration (0.12 %–0.6 %), a reverse trend was observed, which was attributed to the formation of a three-dimensional polymer network. Furthermore, alginate addition shifted the “printability window” of kaolinite mixtures to higher solid contents, which has positive implications on the strength and shrinkage of the printable mixtures.

Polysaccharide-Based Nanogels to Overcome Mucus, Skin, Cornea, and Blood-Brain Barriers: A Review.

Nanocarriers have been extensively developed in the biomedical field to enhance the treatment of various diseases. However, to effectively deliver therapeutic agents to desired target tissues and enhance their pharmacological activity, these nanocarriers must overcome biological barriers, such as mucus gel, skin, cornea, and blood-brain barriers. Polysaccharides possess qualities such as excellent biocompatibility, biodegradability, unique biological properties, and good accessibility, making them ideal materials for constructing drug delivery carriers. Nanogels, as a novel drug delivery platform, consist of three-dimensional polymer networks at the nanoscale, offering a promising strategy for encapsulating different pharmaceutical agents, prolonging retention time, and enhancing penetration. These attractive properties offer great potential for the utilization of polysaccharide-based nanogels as drug delivery systems to overcome biological barriers. Hence, this review discusses the properties of various barriers and the associated constraints, followed by summarizing the most recent development of polysaccharide-based nanogels in drug delivery to overcome biological barriers. It is expected to provide inspiration and motivation for better design and development of polysaccharide-based drug delivery systems to enhance bioavailability and efficacy while minimizing side effects.

Hydrogel-based Drug Delivery System in Diabetes Management.

It is estimated that there are over 200 million people living with diabetes mellitus (DM) all over the world. It is a metabolic condition caused by decreased insulin action or secretion. Diabetes Mellitus is also known as Type 2 Diabetes Mellitus. Type 1 diabetes mellitus and type 2 diabetes mellitus are the two most common types of DM. Treatment for type 1 diabetes often consists of insulin replacement therapy, while treatment for type 2 diabetes typically consists of oral hypoglycemics. Conventional dosing schedules for the vast majority of these medications come with a number of drawbacks, the most common of which are frequent dosing, a short half-life, and low bioavailability. Thus, innovative and regulated oral hypoglycemic medication delivery methods have been developed to reduce the limitations of standard dose forms. The studies and reviews published under the title were looked up in several databases (including PubMed, Elsevier, and Google Scholar). Hydrogels made from biopolymers are three-dimensional polymeric networks that can be physically or chemically crosslinked. These networks are based on natural polymers and have an inherent hydrophilic quality because of the functional groups they contain. They have a very high affinity for biological fluids in addition to a high water content, softness, flexibility, permeability, and biocompatibility. The fact that these features are similar to those of a wide variety of soft living tissues paves the way for several potentials in the field of biomedicine. In this sense, hydrogels offer excellent platforms for the transport of medications and the controlled release of those drugs. Additionally, biopolymer-based hydrogels can be put as coatings on medical implants in order to improve the biocompatibility of the implants and to prevent medical diseases. The current review focuses on the most recent advancements made in the field of using biopolymeric hydrogels that are physically and chemically crosslinked, in addition to hydrogel coatings, for the purpose of providing sustained drug release of oral hypoglycemics and avoiding problems that are associated with the traditional dosage forms of oral hypoglycemics.

Hydroxypropyl Methylcellulose Bioadhesive Hydrogels for Topical Application and Sustained Drug Release: The Effect of Polyvinylpyrrolidone on the Physicomechanical Properties of Hydrogel.

Hydrogels are homogeneous three-dimensional polymeric networks capable of holding large amounts of water and are widely used in topical formulations. Herein, the physicomechanical, rheological, bioadhesive, and drug-release properties of hydrogels containing hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) were examined, and the intermolecular interactions between the polymers were explored. A three-level factorial design was used to form HPMC-PVP binary hydrogels. The physicomechanical properties of the binary hydrogels alongside the homopolymeric HPMC hydrogels were characterized using a texture analyzer. Rheological properties of the gels were studied using a cone and plate rheometer. The bioadhesiveness of selected binary hydrogels was tested on porcine skin. Hydrophilic benzophenone-4 was loaded into both homopolymeric and binary gels, and drug-release profiles were investigated over 24 h at 33 °C. Fourier transform infrared spectroscopy (FTIR) was used to understand the inter-molecular drug-gel interactions. Factorial design analysis supported the dominant role of the HPMC in determining the gel properties, rather than the PVP, with the effect of both polymer concentrations being non-linear. The addition of PVP to the HPMC gels improved adhesiveness without significantly affecting other properties such as hardness, shear-thinning feature, and viscosity, thereby improving bioadhesiveness for sustained skin retention without negatively impacting cosmetic acceptability or ease of use. The release of benzophenone-4 in the HPMC hydrogels followed zero-order kinetics, with benzophenone-4 release being significantly retarded by the presence of PVP, likely due to intermolecular interactions between the drug and the PVP polymer, as confirmed by the FTIR. The HPMC-PVP binary hydrogels demonstrate strong bioadhesiveness resulting from the addition of PVP with desirable shear-thinning properties that allow the formulation to have extended skin-retention times. The developed HPMC-PVP binary hydrogel is a promising sustained-release platform for topical drug delivery.

Pectin Hydrogels: Gel-Forming Behaviors, Mechanisms, and Food Applications.

Pectin hydrogels have garnered significant attention in the food industry due to their remarkable versatility and promising properties. As a naturally occurring polysaccharide, pectin forms three-dimensional (3D) hydrophilic polymer networks, endowing these hydrogels with softness, flexibility, and biocompatibility. Their exceptional attributes surpass those of other biopolymer gels, exhibiting rapid gelation, higher melting points, and efficient carrier capabilities for flavoring and fat barriers. This review provides an overview of the current state of pectin gelling mechanisms and the classification of hydrogels, as well as their crosslinking types, as investigated through diverse research endeavors worldwide. The preparation of pectin hydrogels is categorized into specific gel types, including hydrogels, cryogels, aerogels, xerogels, and oleogels. Each preparation process is thoroughly discussed, shedding light on how it impacts the properties of pectin gels. Furthermore, the review delves into the various crosslinking methods used to form hydrogels, with a focus on physical, chemical, and interpenetrating polymer network (IPN) approaches. Understanding these crosslinking mechanisms is crucial to harnessing the full potential of pectin hydrogels for food-related applications. The review aims to provide valuable insights into the diverse applications of pectin hydrogels in the food industry, motivating further exploration to cater to consumer demands and advance food technology. By exploiting the unique properties of pectin hydrogels, food formulations can be enhanced with encapsulated bioactive substances, improved stability, and controlled release. Additionally, the exploration of different crosslinking methods expands the horizons of potential applications.