Application of stimuli-responsive hydrogel in brain disease treatment

Treating brain diseases presents significant challenges due to neuronal degeneration, inflammation, and the intricate nature of the brain. Stimuli-responsive hydrogels, designed to closely resemble the brain's extracellular matrix, have emerged as promising candidates for controlled drug delivery and tissue engineering. These hydrogels have the unique ability to encapsulate therapeutic agents and release them in a controlled manner when triggered by environmental stimuli. This property makes them particularly suitable for delivering drugs precisely to targeted areas of the brain, while minimizing collateral damage to healthy tissue. Their preclinical success in treating various brain diseases in animal studies underscores their translational potential for human brain disease treatment. However, a deeper understanding of their long-term behavior, biodistribution, and biocompatibility within the brain remains crucial. Furthermore, exploring novel hydrogel systems and therapeutic combinations is paramount for advancing towards more effective treatments. This review summarizes the latest advancements in this field over the past 5 years, specifically highlighting preclinical progress with novel stimuli-responsive hydrogels for treating brain diseases.

A novel pH-responsive hydrogel system based on Prunus armeniaca gum and acrylic acid: Preparation and evaluation as a potential candidate for controlled drug delivery

pH-responsive hydrogels have become effective and attractive materials for the controlled release of drugs at pre-determined destinations. In the present study, a novel hydrogel system based on Prunus armeniaca gum (PAG) and acrylic acid (AA) was prepared by a free radical mechanism using N, N-methylene bisacrylamide (MBA) as cross-linker and potassium persulfate (KPS) as initiator. A series of hydrogels varying PAG, AA, and MBA concentration was developed to determine the impact of these components. Formulated hydrogels were characterized for pH-responsive swelling, drug release, gel content, and porosity. Structural analysis was performed by FTIR, XRD, and SEM analysis. TGA study was applied to assess thermal stability. Oral acute toxicity and in vivo drug release were performed in rabbits. Hydrogels exhibited pH-dependent swelling and drug release. Swelling, drug loading and release, and porosity increased by increasing PAG and AA concentration while decreased by increasing MBA. The gel content of formulations was increased by increasing all three components. FTIR studies confirmed the development of copolymeric networks and the loading of drug. XRD studies revealed that hydrogels were amorphous, and the crystalline drug was changed into an amorphous form during loading. TGA results indicated that hydrogels were stable up to 600 °C. Acute oral toxicity results confirm that hydrogels were nontoxic up to a dose of 2 g/kg body weight in rabbits. The pharmacokinetic evaluation revealed that hydrogels prolonged the availability of the drug and the peak plasma concentration of the drug was obtained in 6 h as compared to the oral solution of the drug. Tramadol hydrochloride (THC) was used as a model drug. Hence, pH-responsive swelling and release, nontoxic nature and improved pharmacokinetics support that PAG-based hydrogels may be considered as potential controlled-release polymeric carriers.

Advances in the Research and Application of Smart-Responsive Hydrogels in Disease Treatment

Smart-responsive hydrogels have been widely used in various fields, particularly in the biomedical field. Compared with traditional hydrogels, smart-responsive hydrogels not only facilitate the encapsulation and controlled release of drugs, active substances, and even cells but, more importantly, they enable the on-demand and controllable release of drugs and active substances at the disease site, significantly enhancing the efficacy of disease treatment. With the rapid advancement of biomaterials, smart-responsive hydrogels have received widespread attention, and a wide variety of smart-responsive hydrogels have been developed for the treatment of different diseases, thus presenting tremendous research prospects. This review summarizes the latest advancements in various smart-responsive hydrogels used for disease treatment. Additionally, some of the current shortcomings of smart-responsive hydrogels and the strategies to address them are discussed, as well as the future development directions and prospects of smart-responsive hydrogels.

Biodegradable Gg-cl-poly(NIPAm-co-AA)/-o-MWCNT based hydrogel for combined drug delivery system of metformin and sodium diclofenac: in vitro studies

In the present study Gg-cl-poly(NIPA-co-AA) and Gg-cl-poly(NIPA-co-AA)/-o-MWCNT hydrogels were synthesized using free radical polymerization. We looked into whether combining metformin with diclofenac, a nonsteroidal anti-inflammatory drug (NSAID), would be effective in examining complex formation and analysing the types and intensities of complexes that could result from metformin-diclofenac interactions. The interaction of metformin and diclofenac was studied in vitro at various pH levels and body temperatures. The structure and morphology of the produced hydrogel were characterised using FTIR spectra, SEM analysis, and drug loading tests. As a model drug, the hydrogel was loaded with metformin hydrochloride and sodium diclofenac (DS), and the medicines were released pH-dependently. To explore the drug release kinetics and mechanism, the zero order and first order kinetic models, the Korsemeyar-Peppas model, the Higuchi model, and the Hixson-Crowell model have all been employed. Drug release studies revealed notable characteristics in connection to physiologically predicted pH values, with a high release rate at pH = 9.2. At pH = 9.2, however, both metformin and sodium diclofenac exhibited a Fickian mechanism. Combination treatment may reduce the effective dose of a single drug and hinder metabolic rescue mechanisms. More study is needed to detect any negative effects on individuals.

Aloe vera-Based Polymeric Network: A Promising Approach for Sustained Drug Delivery, Development, Characterization, and In Vitro Evaluation

The present study was conducted to fabricate and characterize mucilage-based polymeric networks of Aloe vera for controlled drug release. Aloe vera mucilage was used to develop a polymeric network via the free-radical polymerization method using potassium persulphate as the initiator, N' N'-Methylene bisacrylamide as the crosslinker, and acrylamide as the monomer. Using varying concentrations of Aloe vera mucilage, crosslinker, and monomer, we developed different formulations. Swelling studies were conducted at pH 1.2 and 7.4. Concentrations of polymer, monomer, and crosslinker were optimized as a function of swelling. Porosity and gel content were calculated for all samples. FTIR, SEM, XRD, TGA, and DSC studies were conducted for the characterization of polymeric networks. Thiocolchicoside was used as a model drug to study the in vitro release in acidic and alkaline pH. Various kinetics models were applied by using a DD solver. Increasing content of monomer and crosslinker swelling, porosity, and drug release decreased while gel content increased. An increase in Aloe vera mucilage concentration promotes swelling, porosity, and drug release of the polymeric network but decreases gel content. The FTIR study confirmed the formation of crosslinked networks. SEM indicated that the polymeric network had a porous structure. DSC and XRD studies indicated the entrapment of drugs inside the polymeric networks in amorphous form. The analytical method was validated according to ICH guidelines in terms of linearity, range, LOD, LOQ, accuracy, precision, and robustness. Analysis of drug release mechanism revealed Fickian behavior of all formulations. All these results indicated that the M1 formulation was considered to be the best polymeric network formulation in terms of sustaining drug release patterns.

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery-A Bibliometric Review

Food hydrogels are biopolymeric materials made from food-grade biopolymers with gelling properties (proteins and polysaccharides) and a 3D network capable of incorporating large amounts of water. They have sparked considerable interest because of their potential and broad application range in the biomedical and pharmaceutical sectors. However, hydrogel research in the field of food science is still limited. This knowledge gap provides numerous opportunities for implementing their unique properties, such as high water-holding capacity, moderated texture, compatibility with other substances, cell biocompatibility, biodegradability, and high resemblance to living tissues, for the development of novel, functional food matrices. For that reason, this article includes a bibliometric analysis characterizing research trends in food protein-polysaccharide hydrogels (over the last ten years). Additionally, it characterizes the most recent developments in hydrogel induction methods and the most recent application progress of hydrogels as food matrices as carriers for the targeted delivery of bioactive compounds. Finally, this article provides a future perspective on the need to evaluate the feasibility of using plant-based proteins and polysaccharides to develop food matrices that protect nutrients, including bioactive substances, throughout processing, storage, and digestion until they reach the specific targeted area of the digestive system.

Development and Evaluation of Cellulose Derivative and Pectin Based Swellable pH Responsive Hydrogel Network for Controlled Delivery of Cytarabine

In the present study, pH-sensitive, biodegradable, and biocompatible Na-CMC/pectin poly(methacrylic acid) hydrogels were synthesized using an aqueous free radical polymerization technique and encapsulated by cytarabine (anti-cancer drug). The aim of the project was to sustain the plasma profile of cytarabine through oral administration. Sodium carboxymethyl cellulose (Na-CMC) and pectin were cross-linked chemically with methacrylic acid (MAA) as a monomer, using methylene bisacrylamide (MBA) as cross-linker and ammonium per sulfate (APS) as an initiator. Prepared hydrogel formulations were characterized for their texture, morphology, cytarabine loading efficiency, compositional and structural properties, thermal nature, stability, swelling response, drug release profile (pH 1.2 and pH 7.4), and in-vivo pharmacokinetic evaluation. Cytarabine-loaded hydrogels were also evaluated for their safety profile by carrying out toxicity studies in rabbits. Results demonstrated efficient encapsulation of cytarabine into the prepared network with loading ranging from 48.5-82.3%. The highest swelling ratio of 39.38 and maximum drug release of 83.29-85.27% were observed at pH 7.4, highlighting the pH responsiveness of the grafted system. Furthermore, cytarabine maximum release was noticed over 24 h, ensuring a sustained release response for all formulations. Histopathological studies and hemolytic profiles confirmed that the prepared hydrogel system was safe, biocompatible, and non-irritant, showing no symptoms of any toxicities and degeneration in organs. Moreover, pharmacokinetic estimation of the cytarabine-loaded hydrogel showed a remarkable increase in the plasma half-life from 4.44 h to 9.24 h and AUC from 22.06 μg/mL.h to 56.94 μg/mL.h. This study revealed that the prepared hydrogel carrier system has excellent abilities in delivering the therapeutic moieties in a controlled manner.

Development of hydrogel based on Carboxymethyl cellulose/poly(4-vinylpyridine) for controlled releasing of fertilizers

A novel Carboxymethyl cellulose (CMC) and poly (4-vinylpyridine) (P4VP) hydrogel system is synthesized with different ratios, in the presence of cross-linker N, N,- methylene bis-acrylamide (MBA). The hydrogel is characterized via FTIR spectroscopy, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The FTIR results showed a strong interaction between both CMC, P4VP and the loaded fertilizer. The water uptake of the hydrogel was evaluated by swelling tests under variations in pH, biodegradability was investigated in soil to simulate real-world conditions. To determine the best release behavior of urea and calcium nitrate from the hydrogel, fertilizers were loaded with different ratios onto the hydrogel during its formation. Fertilizers release was followed by Atomic absorption spectroscopy to study the release of calcium nitrate and urea. Release kinetic parameters were obtained based on different mathematical models as Zero order, First order, Korsmeyer–Peppas and Higuchi models. The suitable proportionality between the mathematical models used and the fertilizers release was determined based on the correlation coefficients (R²). According to Zero order model urea release showed independent concentration. Based on Korsmeyer-Pappas and Higuchi models with high n value and R² equals to 0.97. Compared to urea, Ca²⁺, Zero order and Higuchi have been ignored due to their poor correlation coefficients values as proportion with Ca²⁺ fertilizer release.

Characteristic and mechanism analysis of sludge polymer by adding carboxymethyl cellulose-g-acrylic acid for sludge utilization

Herein, a nutrient water retention agent is prepared by fully mixing sludge with carboxymethyl cellulose-g-acrylic acid (CMC-g-AA) gel and nanoscale zero-valent iron (nZVI) using polymer modifying curing technology. Experimental results show that when CMC:AA = 1:12 and CMC-g-AA gel content is 50%, sludge polymer has better water absorption and retention performance and the water retention time is extended for ∼14 days. At the same time, sludge polymer can preserve the characteristics of nutrient-rich elements and organic matter and promote plant growth. The addition of nZVI has a significant impact on reducing the risk of heavy metal toxic leaching in sludge. Moreover, analysis of variance and multiple comparisons shows that sludge polymer's particle size and water absorption times have significant effects on the water absorption and retention properties of sludge polymer. Scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and ¹³C-nuclear magnetic resonance analyses show that the addition of an appropriate amount of gel could increase the number of hydrophilic groups and hydrophilic mineral components in sludge polymer, increase its overall porosity and improve its water absorption and retention properties.

pH Sensitive Pluronic Acid/Agarose-Hydrogels as Controlled Drug Delivery Carriers: Design, Characterization and Toxicity Evaluation

The objective of this study was to fabricate and evaluate a pH sensitive cross-linked polymeric network through the free radical polymerization technique for the model drug, cyclophosphamide, used in the treatment of non-Hodgkin’s lymphoma. The Hydrogels were prepared using a polymeric blend of agarose, Pluronic acid, glutaraldehyde, and methacrylic acid. The prepared hydrogels were characterized for drug loading (%), swelling pattern, release behavior, the ingredient’s compatibility, structural evaluation, thermal integrity, and toxicity evaluation in rabbits. The new polymer formation was evident from FTIR findings. The percentage loaded into the hydrogels was in the range of 58.65–75.32%. The developed hydrogels showed significant differences in swelling dynamics and drug release behavior in simulated intestinal fluid (SIF) when compared with simulated gastric fluid (SGF). The drug release was persistent and performed in a controlled manner for up to 24 h. A toxicity study was conducted on white albino rabbits. The developed hydrogels did not show any signs of ocular, skin, or oral toxicity; therefore, these hydrogels can be regarded as safe and potential carriers for controlled drug delivery in biomedical applications.

Synthesis of pH-Sensitive Cross-Linked Basil Seed Gum/Acrylic Acid Hydrogels by Free Radical Copolymerization Technique for Sustained Delivery of Captopril

The pH-sensitive polymeric matrix of basil seed gum (BSG), with two different monomers, such as acrylic acid (AA) and N, N-Methylene-bis-acrylamide (MBA), was selected to use in hydrogels preparation through a free radical copolymerization technique using potassium per sulfate (KPS) as a cross linker. BSG, AA and MBA were used in multiple ratios to investigate the polymer, monomer and initiator effects on swelling properties and release pattern of captopril. Characterization of formulated hydrogels was done by FTIR, DSC/TGA, XRD and SEM techniques to confirm the stability. The hydrogels were subjected to a variety of tests, including dynamic swelling investigations, drug loading, in vitro drug release, sol–gel analyses and rheological studies. FTIR analysis confirmed that after the polymeric reaction of BSG with the AA monomer, AA chains grafted onto the backbone of BSG. The SEM micrographs illustrated an irregular, rough, and porous form of surface. Gel content was increased by increasing the contents of polymeric gum (BSG) with monomers (AA and MBA). Acidic and basic pH effects highlighted the difference between the swelling properties with BSG and AA on increasing concentration. Kinetic modelling suggested that Korsmeyer Peppas model release pattern was followed by the drug with the non-Fickian diffusion mechanism.

Biopolymer Hydrogel Based on Acid Whey and Cellulose Derivatives for Enhancement Water Retention Capacity of Soil and Slow Release of Fertilizers

This study describes the development of a renewable and biodegradable biopolymer-based hydrogel for application in agriculture and horticulture as a soil conditioning agent and for release of a nutrient or fertilizer. The novel product is based on a combination of cellulose derivatives (carboxymethylcellulose and hydroxyethylcellulose) cross-linked with citric acid, as tested at various concentrations, with acid whey as a medium for hydrogel synthesis in order to utilize the almost unusable by-product of the dairy industry. The water uptake of the hydrogel was evaluated by swelling tests under variations in pH, temperature and ion concentration. Its swelling capacity, water retention and biodegradability were investigated in soil to simulate real-world conditions, the latter being monitored by the production of carbon dioxide during the biodegradation process by gas chromatography. Changes in the chemical structure and morphology of the hydrogels during biodegradation were assessed using Fourier transform infrared spectroscopy and scanning electron microscopy. The ability of the hydrogel to hold and release fertilizers was studied with urea and KNO₃ as model substances. The results not only demonstrate the potential of the hydrogel to enhance the quality of soil, but also how acid whey can be employed in the development of a soil conditioning agent and nutrient release products.

Formulation, In Vitro Evaluation, and Toxicity Studies of A. vulgaris-co-AAm Carrier for Vildagliptin

This study investigated the use of Artemisia vulgaris L. seed mucilage as a new excipient for sustained delivery of Vildagliptin. Copolymeric carrier of A. vulgaris seed mucilage-co-AAm was devised by using acrylamide (AAm) as a monomer, methylene-bis-acrylamide (MBA) as a crosslinker, and potassium persulfate (KPS) as an initiator through free radical polymerization. Different formulations of A. vulgaris-co-AAm were devised by varying contents of polymer, monomer, crosslinking agent, initiator, and reaction temperature. Copolymeric structures were characterized through XRD analysis, Fourier transform infrared (FTIR) spectroscopy, TGA and DSC analysis, and scanning electron microscopy. Porosity, gel fraction, and Vildagliptin loading capacity of copolymers were also established. Swelling and in vitro drug release studies were conducted. XRD evaluation showed the alteration of the crystalline structure of Vildagliptin into an amorphous form. FTIR analysis confirmed the successful grafting of AAm to A. vulgaris seed mucilage backbone. Porosity was increased with increasing polymer concentration and reaction temperature while it was decreased with an increasing amount of AAm, MBA, and KPS. Gel content was decreased with increasing polymer concentration and reaction temperature while it was increased with an increasing amount of AAm, MBA, and KPS. Acute oral toxicity of copolymeric network was done in animal models to evaluate the safety. Copolymers showed the same swelling behavior at all pH 1.2, 4.5, 6.8, and 7.4. Vildagliptin release from copolymer showed a cumulative trend by increasing polymer content and reaction temperature, while a declining trend was observed with increasing contents of monomer, crosslinking agent, and initiator. Sustained release of Vildagliptin was observed from copolymers and release followed the Korsmeyer-Peppas model. From the acute oral toxicity studies, it is evident that newly synthesized copolymeric carriers are potentially safe for eyes, skin, and vital organs.

Hydrogels Based Drug Delivery Synthesis, Characterization and Administration

Hydrogels represent 3D polymeric networks specially designed for various medical applications. Due to their porous structure, they are able to swollen and to entrap large amounts of therapeutic agents and other molecules. In addition, their biocompatibility and biodegradability properties, together with a controlled release profile, make hydrogels a potential drug delivery system. In vivo studies have demonstrated their effectiveness as curing platforms for various diseases and affections. In addition, the results of the clinical trials are very encouraging and promising for the use of hydrogels as future target therapy strategies.