Hydrogels for Hydrophobic Drug Delivery. Classification, Synthesis and Applications

Chemical modification of hyaluronic acid as a strategy for the development of advanced drug delivery systems

Hyaluronic acid (HA) has emerged as a promising biopolymer for various biomedical applications due to its biocompatibility, biodegradability, and intrinsic ability to interact with cell surface receptors, making it an attractive candidate for drug delivery systems and tissue engineering. Chemical modification of HA has opened up versatile possibilities to tailor its properties, enabling the development of advanced drug delivery systems and biomaterials with enhanced functionalities and targeted applications. This review analyzes the strategies and applications of chemically modified HA in the field of drug delivery and biomaterial development. The first part of the review focuses on the different methods and functional groups used for the chemical modification of HA, highlighting the impact of these modifications on its physicochemical properties, degradation behavior and interactions with drugs. The second part of the review evaluates the use of chemically modified HA in the development of advanced biomedical materials including nano- and microparticles, hydrogels and mucoadhesive materials with tailored drug release profiles, site-specific targeting and stimuli-responsive behavior. Thus, the review consolidates the current advances and future perspectives in the field of chemical modification of HA, underscoring its immense potential to drive the development of advanced drug delivery systems and biomaterials with diverse biomedical applications.

Evaluation of Emulgel and Nanostructured Lipid Carrier-Based Gel Formulations for Transdermal Administration of Ibuprofen: Characterization, Mechanical Properties, and Ex-Vivo Skin Permeation

In transdermal applications of nonsteroidal anti-inflammatory drugs, the rheological and mechanical properties of the dosage form affect the performance of the drug. The aim of this study to develop emulgel and nanostructured lipid carrier NLC-based gel formulations containing ibuprofen, evaluate their mechanical properties, bioadhesive value and ex-vivo rabbit skin permeability. All formulations showed non-Newtonian pseudoplastic behavior and their viscosity values are suitable for topical application. The particle size of the nanostructured lipid carrier system was found to be 468 ± 21 nm, and the encapsulation efficiency was 95.58 ± 0.41%. According to the index of viscosity, consistency, firmness, and cohesiveness values obtained as a result of the back extrusion study, E2 formulation was found to be more suitable for transdermal application. The firmness and work of shear values of the E2 formulation, which has the highest viscosity value, were also found to be the highest and it was chosen as the most suitable formulation in terms of the spreadability test. The work of bioadhesion values of NLC-based gel and IBU-loaded NLC-based gel were found as 0.226 ± 0.028 and 0.181 ± 0.006 mJ/cm2 respectively. The percentages of IBU that penetrated through rabbit skin from the Ibuactive-Cream and the E2 were 87.4 ± 2.11% and 93.4 ± 2.72% after 24 h, respectively. When the penetration of ibuprofen through the skin was evaluated, it was found that the E2 formulation increased penetration due to its lipid and nanoparticle structure. As a result of these findings, it can be said that the NLC-based gel formulation will increase the therapeutic efficacy and will be a good alternative transdermal formulation.

Design and synthesis of drug hydrogels containing carboxymethylcellulose with honeycomb structure and pH-sensitivity as drug delivery systems for adriamycin, metformin, and naproxen

The aim of this research is to prepare and identify functionalized carboxymethylcellulose/mesoporous silica nanohydrogels (CMC/NH2-MCM-41) for obtaining a pH-sensitive system for the controlled release of drugs. The beads of CMC/NH2-MCM-41 nanocomposites were prepared by dispersing NH2-MCM-41 in a CMC polymer matrix and crosslinking with ferric ions (Fe3+). The SEM analysis of samples revealed enhancement in surface porosity of the functionalized nanohydrogel beads compared to the conventional beads. Swelling of the prepared functionalized nanohydrogels was evaluated at various pH values including pH = 7.35-7.45 (simulated body fluid or healthy cells), pH = 6 (simulated intestinal fluid), and pH = 1.5-3.5 (simulated gastric fluid). The swelling of CMC/MCM-41 and CMC/NH2-MCM-41 nanohydrogels at the pH values of simulated body fluid and simulated intestinal fluid is much higher than that of simulated gastric fluid, indicating successful synthesis of pH-sensitive nanohydrogels for drug delivery. The drug loading results showed that drug release in the CMC/NH2-MCM-41 system is much slower than that in the CMC/MCM-41 system. The results of the survival studies for the manufactured systems showed a very good biocompatibility of the designed drug delivery systems for biological applications. By coating the surface of functionalized mesopores with CMC hydrogel, we were able to develop a pH-sensitive intelligent drug delivery system.

Acid and Glutathione Dual-Responsive, Injectable and Self-Healing Hydrogels for Controlled Drug Delivery

Considering the complexity of physiological microenvironments and the risks of surgical infection, there still remains critical demand to develop a hydrogel as a drug release platform with multifunctional properties, including good neutral stability and sensitive multiple stimuli-responsive behaviors, as well as injectable and self-healing properties. Herein, we present a facile preparation of injectable, self-healing hydrogels with acid and glutathione (GSH) dual-responsiveness for controlled drug delivery. Initially, the anticancer drug camptothecin (CPT) was premodified with disulfide bonds and attached to poly(ethylenimine) (PEI) via the Schiff base reaction, resulting in PEI-CPT. Subsequently, OSA-IR780 was synthesized through the Schiff base reaction involving IR780 with amine groups (IR780-NH2) and oxidized sodium alginate with aldehyde groups (OSA). The formation of PEI-CPT/OSA-IR780 hydrogels with various solid contents occurred rapidly within 40 s through a simple mixing process of the aqueous solution of PEI-CPT and OSA-IR780. These hydrogels exhibited remarkable stability under neutral conditions and controlled release of CPT upon exposure to simulated tumor environments characterized by acidic conditions and elevated GSH concentrations. Furthermore, they had significant injectable and self-healing properties due to the dynamically imine-cross-linked networks. In addition, the prepared hydrogels exhibited long-term biodegradability and biocompatibility. Collectively, these features indicate the great potential of PEI-CPT/OSA-IR780 hydrogels as therapeutic delivery vehicles.

pNIPAm-Based pH and Thermoresponsive Copolymer Hydrogel for Hydrophobic and Hydrophilic Drug Delivery

The regulated and targeted administration of hydrophobic and hydrophilic drugs is both promising and challenging in the field of drug delivery. Developing a hydrogel which is responsive to dual stimuli is considered a promising and exciting research area of study. In this work, melamine functionalized poly-N-isopropyl acrylamide-co-glycidyl methacrylate copolymer has been developed by copolymerizing glycidyl methacrylate (GMA) monomer with N-isopropyl acrylamide (NIPAm) and further functionalized with melamine units (pNIPAm-co-pGMA-Mela). The prepared pNIPAm-co-pGMA-Mela copolymer hydrogel was characterized using various characterization techniques, including 1H NMR, FTIR, SEM, zeta potential, and particle size analysis. A hydrophobic drug (ibuprofen, Ibu) and hydrophilic drug (5-fluorouracil, 5-Fu) were selected as model drugs. Dual pH and temperature stimuli-responsive drug release behavior of the pNIPAm-co-pGMA-Mela hydrogel was evaluated under different pH (pH 7.4 and 4.0) and temperature (25 °C, 37 °C, and 45 °C) conditions. Furthermore, the in vitro biocompatibility of the developed pNIPAm-co-pGMA-Mela copolymer hydrogel was determined on MDA-MB-231 cells. The pH and temperature-responsive drug delivery study results reveal that the pNIPAm-co-pGMA-Mela hydrogel system is responsive to both pH and temperature stimuli and exhibits about ~100% of Ibu and 5-Fu, respectively, released at pH 4.0/45 °C. Moreover, the MTT assay and hemocompatibility analysis results proved that the pNIPAm-co-pGMA-Mela hydrogel system is biocompatible and hemocompatible, suggesting that that it could be used for drug delivery applications. The experimental results suggest that the proposed pNIPAm-co-pGMA-Mela hydrogel system is responsive to dual pH and temperature stimuli, and could be a promising drug carrier system for both hydrophilic and hydrophobic drug delivery applications.

Lecithin Organogel: A Promising Carrier for the Treatment of Skin Diseases

Skin is the largest organ of the human body, as it protects the body from the external environment. Nowadays, skin diseases and skin problems are more common, and millions of people are affected daily. Skin diseases are due to numerous infectious pathogens or inflammatory conditions. The increasing demand for theoretical research and practical applications has led to the rising prominence of gel as a semisolid material. To this end, organogels has been widely explored due to their unique composition, which includes organic solvents and mineral or vegetable oils, among others. Organogels can be described as semisolid systems wherein an organic liquid phase is confined within a three-dimensional framework consisting of self-assembled, cross-linked, or entangled gelator fibers. These gels have the ability to undergo significant expansion and retain substantial amounts of the liquid phase, reaching up to 99% swelling capacity. Furthermore, they respond to a range of physical and chemical stimuli, including temperature, light, pH, and mechanical deformation. Notably, due to their distinctive properties, they have aroused significant interest in a variety of practical applications. Organogels favor the significant encapsulation and enhanced permeation of hydrophobic molecules when compared with hydrogels. Accordingly, organogels are characterized into lecithin organogels, pluronic lecithin organogels, sorbitan monostearate-based organogels, and eudragit organogels, among others, based on the nature of their network and the solvent system. Lecithin organogels contain lecithin (natural and safe as a living cell component) as an organogelator. It acts as a good penetration enhancer. In this review, first we have summarized the fundamental concepts related to the elemental structure of organogels, including their various forms, distinctive features, methods of manufacture, and diverse applications. Nonetheless, this review also sheds light on the delivery of therapeutic molecules entrapped in the lecithin organogel system into deep tissue for the management of skin diseases and provides a synopsis of their clinical applications.

Recent advances of electrospray technique for multiparticulate preparation: Drug delivery applications

The electrospray (ES) technique has proven to be an effective and a versatile approach for crafting drug delivery carriers with diverse dimensions, multiple layers, and varying morphologies. Achieving the desired particle properties necessitates careful optimization of various experimental parameters. This review delves into the most prevalent ES system configurations employed for this purpose, such as monoaxial, coaxial, triaxial, and multi-needle setups with solid or liquid collector. In addition, this work underscores the significance of ES in drug delivery carriers and its remarkable ability to encapsulate a wide spectrum of therapeutic agents, including drugs, nucleic acids, proteins, genes and cells. Depth examination of the critical parameters governing the ES process, including the choice of polymer, surface tension, voltage settings, needle size, flow rate, collector types, and the collector distance was conducted with highlighting on their implications on particle characteristics, encompassing morphology, size distribution, and drug encapsulation efficiency. These insights illuminate ES's adaptability in customizing drug delivery systems. To conclude, this review discusses ES process optimization strategies, advantages, limitations and future directions, providing valuable guidance for researchers and practitioners navigating the dynamic landscape of modern drug delivery systems.

Proposing lead compounds for the development of SARS-CoV-2 receptor-binding inhibitors

The COVID-19 pandemic has had deleterious effects on the world and demands urgent measures to find therapeutic agents to combat the current and related future outbreaks. The entry of SARS-CoV-2 into the host's cell is facilitated by the interaction between the viral spike receptor-binding domain (sRBD) and the human angiotensin-converting enzyme 2 (hACE2). Although the interface of sRBD involved in the sRBD-hACE2 interaction has been projected as a primary vaccine and drug target, currently no small-molecule drugs have been approved for covid-19 treatment targeting sRBD. Herein structure-based virtual screening and molecular dynamics (MD) simulation strategies were applied to identify novel potential small-molecule binders of the SARS-CoV-2 sRBD from an sRBD-targeted compound library as leads for the development of anti-COVID-19 drugs. The library was initially screened against sRBD by using the GOLD docking program whereby 19 compounds were shortlisted based on docking scores after using a control compound to set the selection cutoff. The stability of each compound in MD simulations was used as a further standard to select four hits namely T4S1820, T4589, E634-1449, and K784-7078. Analyses of simulations data showed that the four compounds remained stably bound to sRBD for ≥ 80 ns with reasonable affinities and interacted with pharmacologically important amino acid residues. The compounds exhibited fair solubility, lipophilicity, and toxicity-propensity characteristics that could be improved through lead optimization regimes. The overall results suggest that the scaffolds of T4S1820, E634-1449, and K784-7078 could serve as seeds for developing potent small-molecule inhibitors of SARS-CoV-2 receptor binding and cell entry.Communicated by Ramaswamy H. Sarma.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.

Bifunctional Carbosilane Dendrimers for the Design of Multipurpose Hydrogels with Antibacterial Action

The emergence of antibiotic resistance is a serious global health problem. There is an incessant demand for new antimicrobial drugs and materials that can address this global issue from different angles. Dendritic hydrogels have appeared as a promising strategy. A family of bifunctional amphiphilic carbosilane dendrimers was designed and employed as nanosized cross-linking points for the synthesis of high-swelling hydrogels using the highly efficient Thiol-Ene click reaction for their preparation. Both stoichiometric and off-stoichiometric conditions were studied, generating hydrogels with pendant hydroxyl or alkene moieties. These hydrogels were found to be tunable antibacterial materials. They can easily be postmodified with relevant antibiotic moieties through covalent attachment on the hydroxyl or alkene pendant groups, generating ammonium-decorated networks with temperature and pH-responsive properties. Additionally, they can efficiently encapsulate drugs with poor solubility in water, like ciprofloxacin, and perform a sustained release over time, as demonstrated in preliminary assays against Staphylococcus aureus.

A Comprehensive Review on Current Treatments and Challenges Involved in the Treatment of Ovarian Cancer

Ovarian cancer (OC) is the second most common gynaecological malignancy. It typically affects females over the age of 50, and since 75% of cases are only discovered at stage III or IV, this is a sign of a poor diagnosis. Despite intraperitoneal chemotherapy's chemosensitivity, most patients relapse and face death. Early detection is difficult, but treatment is also difficult due to the route of administration, resistance to therapy with recurrence, and the need for precise cancer targeting to minimize cytotoxicity and adverse effects. On the other hand, undergoing debulking surgery becomes challenging, and therapy with many chemotherapeutic medications has manifested resistance, a condition known as multidrug resistance (MDR). Although there are other therapeutic options for ovarian cancer, this article solely focuses on co-delivery techniques, which work via diverse pathways to overcome cancer cell resistance. Different pathways contribute to MDR development in ovarian cancer; however, usually, pump and non-pump mechanisms are involved. Striking cancerous cells from several angles is important to defeat MDR. Nanocarriers are known to bypass the drug efflux pump found on cellular membranes to hit the pump mechanism. Nanocarriers aid in the treatment of ovarian cancer by enhancing the delivery of chemotherapeutic drugs to the tumour sites through passive or active targeting, thereby reducing unfavorable side effects on the healthy tissues. Additionally, the enhanced permeability and retention (EPR) mechanism boosts the bioavailability of the tumour site. To address the shortcomings of conventional delivery, the current review attempts to explain the current conventional treatment with special reference to passively and actively targeted drug delivery systems (DDSs) towards specific receptors developed to treat ovarian cancer. In conclusion, tailored nanocarriers would optimize medication delivery into the intracellular compartment before optimizing intra-tumour distribution. Other novel treatment possibilities for ovarian cancer include tumour vaccines, gene therapy, targeting epigenetic alteration, and biologically targeted compounds. These characteristics might enhance the therapeutic efficacy.

Evaluation of hyaluronic acid-polymacrolactone hydrogels with 3D printing capacity

The implementation of personalized patches, tailored to individual genetic profiles and containing specific amounts of bioactive substances, has the potential to produce a transformative impact within the medical sector. There are several methods of designing scaffolds in the context of personalized medicine, with three-dimensional (3D) printing emerging as a pivotal technique. This innovative approach can be used to construct a wide variety of pharmaceutical dosage forms, characterized by variations in shape, release profile, and drug combinations, allowing precise dose individualization and the incorporation of multiple therapeutic agents. To expand the potential and applicability of personalized medicine, particularly with regards to indomethacin (IND), a drug necessitating individualized dosing, this study proposes the development of new transdermal delivery systems for IND based on hyaluronic acid and a polylactone synthesized within our research group, namely poly(ethylene brasilate-co-squaric acid) (PEBSA). The obtained systems were characterized in terms of their swelling capacity, rheological behavior, and morphological characteristics that highlighted the formation of stable three-dimensional networks. To impart specific shape and geometry to the structures, multi-component systems based on PEBSA, HA, and methacrylate gelatin were obtained. The scaffolds were loaded with IND and subsequently 3D printed. The release capacity of IND and its dependence on the relative ratios of the components comprising the scaffold composition were highlighted. The cytocompatibility studies revealed the successful development of biocompatible and noncytotoxic systems.

Peptide-Hydrogel Nanocomposites for Anti-Cancer Drug Delivery

Cancer is the second leading cause of death globally, but conventional anticancer drugs have side effects, mainly due to their non-specific distribution in the body in both cancerous and healthy cells. To address this relevant issue and improve the efficiency of anticancer drugs, increasing attention is being devoted to hydrogel drug-delivery systems for different kinds of cancer treatment due to their high biocompatibility and stability, low side effects, and ease of modifications. To improve the therapeutic efficiency and provide multi-functionality, different types of nanoparticles (NPs) can be incorporated within the hydrogels to form smart hydrogel nanocomposites, benefiting the advantages of both counterparts and suitable for advanced anticancer applications. Despite many papers on non-peptide hydrogel nanocomposites, there is limited knowledge about peptide-based nanocomposites, specifically in anti-cancer drug delivery. The aim of this short but comprehensive review is, therefore, to focus attention on the synergies resulting from the combination of NPs with peptide-based hydrogels. This review, which includes a survey of recent advances in this kind of material, does not aim to be an exhaustive review of hydrogel technology, but it instead highlights recent noteworthy publications and discusses novel perspectives to provide valuable insights into the promising synergic combination of peptide hydrogels and NPs for the design of novel anticancer drug delivery systems.

β-Cyclodextrin functionalized agarose-based hydrogels for multiple controlled drug delivery of ibuprofen

Agarose hydrogels are three-dimensional hydrophilic polymeric frameworks characterised by high water content, viscoelastic properties, and excellent ability as cell and drug delivery systems. However, their hydrophilicity as gel systems makes loading of hydrophobic drugs difficult and often ineffective. The incorporation of amphiphilic molecules (e.g. cyclodextrins) into hydrogels as hosts able to form inclusion complexes with hydrophobic drugs could be a possible solution. However, if not properly confined, the host compounds can get out of the network resulting in uncontrolled release. Therefore, in this work, β-cyclodextrins-based host-guest supramolecular hydrogel systems were synthesised, with β-cyclodextrins (β-CD) covalently bound to the polymeric network, preventing leakage of the host molecules. Hydrogels were prepared at two different β-CD-functionalized polyvinyl alcohol (PVA)/agarose ratios, and characterised chemically and physically. Then ibuprofen, a drug often used as a gold standard in studies involving β-CD both in its hydrophilic and hydrophobic forms, was selected to investigate the release behavior of the synthesised hydrogels and the influence of β-CD on the release. The presence of β-CD linked to the polymeric 3D network ensured a higher and prolonged release profile for the hydrophobic drug and also seemed to have some influence on the hydrophilic one.

Liposomal form of 2-alkylthioimidazolone-based copper complexes for combined cancer therapy

Aim: To develop an optimized approach for encapsulating a 2-alkylthioimidazolone-based copper coordination compound within liposomes, which could offer treatment of cancer and bacterial infections by reactive oxygen species generation toxicity mechanisms. Materials & methods: For drug-loaded liposome preparation, lipids and drug mixture in organic solvents was injected into copper salt solution, forming a coordination compound simultaneously embedded in the lipid bilayer. In vitro tests were performed on MCF7 and MDA-MB-231 breast cancer cells. Results: Liposomes had a loading capacity of up to 1.75% (molar drug-to-lipid ratio). In vitro tests showed increased viability and accumulation of the liposomal formulation compared with free drug as well as lack of cytotoxicity in hepatocytes. Conclusion: This optimized technique for encapsulating large copper complexes in liposomes could be used to improve their delivery and better treat cancer and bacterial infections.

Functional hydrogel-based wound dressings: A review on biocompatibility and therapeutic efficacy

Chronic wounds, burns, and surgical incisions represent critical healthcare challenges that significantly impact patient quality of life and strain healthcare resources. In response to these pressing needs, the field of wound healing has witnessed a radical advancement with the emergence of functional hydrogel-based dressings. This review article underscores the severity and importance of this transformative study in the domain of wound healing. The hydrogel matrix offers a moist and supportive environment that facilitates cellular migration, proliferation, and tissue regeneration, vital for efficient wound closure. Their conformable nature ensures patient comfort, reducing pain and uneasiness during dressing changes, particularly in chronic wounds where frequent interventions are required. Beyond their structural merits, functional hydrogel dressings possess the capability of incorporating bioactive molecules such as growth factors and antimicrobial agents. This facilitates targeted and sustained delivery of therapeutics directly to the wound site, addressing the multifactorial nature of chronic wounds and enhancing the healing trajectory. The integration of advanced nanotechnology has propelled the design of hydrogel dressings with enhanced mechanical strength and controlled drug release profiles, amplifying their therapeutic potential. In conclusion, the significance of this study lies in its ability to revolutionize wound healing practices and positively impact the lives of countless individuals suffering from chronic wounds and burns. As this transformative technology gains momentum, it holds the promise of addressing a major healthcare burden worldwide, thus heralding a new era in wound care management.

Directing cellular responses in a nanocomposite 3D matrix for tissue regeneration with nanoparticle-mediated drug delivery

Hydrogels play an important role in tissue engineering due to their native extracellular matrix-like characteristics, but they are insufficient in providing the necessary stimuli to support tissue formation. Efforts to integrate bioactive cues directly into hydrogels are hindered by incompatibility with hydrophobic drugs, issues of burst/uncontrolled release, and rapid degradation of the bioactive molecules. Skeletal muscle tissue repair requires internal stimuli and communication between cells for regeneration, and nanocomposite systems offer to improve the therapeutic effects in tissue regeneration. Here, the versatility of mesoporous silica nanoparticles (MSN) was leveraged to formulate a nanoparticle-hydrogel composite and to combine the benefits of controlled delivery of bioactive cues and cellular support. The tunable surface characteristics of MSNs were exploited to optimize homogeneity and intracellular drug delivery in a 3D matrix. Nanocomposite hydrogels formulated with acetylated or succinylated MSNs achieved high homogeneity in 3D distribution, with succinylated MSNs being rapidly internalized and acetylated MSNs exhibiting slower cellular uptake. MSN-hydrogel nanocomposites simultaneously allowed efficient local intracellular delivery of a hydrophobic model drug. To further study the efficiency of directing cell response, a Notch signaling inhibitor (DAPT) was incorporated into succinylated MSNs and incorporated into the hydrogel. MSN-hydrogel nanocomposites effectively downregulated the Notch signaling target genes, and accelerated and maintained the expression of myogenic markers. The current findings demonstrate a proof-of-concept in effective surface engineering strategies for MSN-based nanocomposites, suited for hydrophobic drug delivery in tissue regeneration with guided cues.

Hydration-induced Void-containing Hydrogels for Encapsulation and Sustained Release of Small Hydrophilic Molecules

Efficient encapsulation and sustained release of small hydrophilic molecules from traditional hydrogel systems have been challenging due to the large mesh size of 3D networks and high water content. Furthermore, the encapsulated molecules are prone to early release from the hydrogel prior to use, resulting in a short shelf life of the formulation. Here, we present a hydration-induced void-containing hydrogel (HVH) based on hyperbranched polyglycerol-poly(propylene oxide)-hyperbranched polyglycerol (HPG-PPG-HPG) as a robust and efficient delivery system for small hydrophilic molecules. Specifically, after the HPG-PPG-HPG is incubated overnight at 4 °C in the drug solution, it is hydrated into a hydrogel containing micron-sized voids, which could encapsulate hydrophilic drugs and achieve 100% drug encapsulation efficiency. In addition, the voids are surrounded by a densely packed polymer matrix, which restricts drug transport to achieve sustained drug release. The hydrogel/drug formulation can be stored for several months without changing the drug encapsulation and release properties. HVH hydrogels are injectable due to shear thinning properties. In rats, a single injection of the HPG-PPG-HPG hydrogel containing 8 μg of tetrodotoxin (TTX) produced sciatic nerve block lasting up to 10 hours without any TTX-related systemic toxicity nor local toxicity to nerves and muscles.

Rheological Study of the Formation of Pullulan Hydrogels and Their Use as Carvacrol-Loaded Nanoemulsion Delivery Systems

Hydrogels have been extensively studied as delivery systems for lipophilic compounds. Pullulan hydrogels were prepared, and their gelation kinetics were studied over time. Pullulan exhibited a relatively slow gelling reaction in basic medium (KOH) using trisodium metaphosphate (STMP) as a cross-linking agent, so capsules cannot be obtained by dripping as easily as in the case of alginate and chitosan. The kinetics of pullulan gelation were studied through rheological analysis over time. An optimal [Pullulan]/[KOH] ratio was found for a fixed [Pullulan]/[STMP] ratio. For this given relationship, gelling time measurements indicated that when the concentration of pullulan increased, the gelation time decreased from 60 min for 6% w/w pullulan to 10 min for 10% w/w. After the gel point, a hardening of the hydrogel was observed over the next 5 h. The formed hydrogels presented high degrees of swelling (up to 1800%). Freeze-dried gels were capable of being rehydrated, obtaining gels with rheological characteristics and visual appearance similar to fresh gels, which makes them ideal to be freeze-dried for storage and rehydrated when needed. The behavior of the hydrogels obtained as active ingredient release systems was studied. In this case, the chosen molecule was carvacrol (the main component of oregano oil). As carvacrol is hydrophobic, it was incorporated into the droplets of an oil-in-water nanoemulsion, and the nanoemulsion was incorporated into the hydrogel. The release of the oil was studied at different pHs. It was observed that as the pH increased (from pH 2 to pH 7), the released amount of carvacrol for the gel with pullulan 10% w/w reached 100%; for the other cases, the cumulative release amount was lower. It was attributed to two opposite phenomena in the porous structure of the hydrogel, where more porosity implied a faster release of carvacrol but also a higher degree of swelling that promoted a higher entry of water flow in the opposite direction. This flow of water prevented the active principle from spreading to the release medium.

Polymer based dual drug delivery system for targeted treatment of fluoroquinolone resistant Staphylococcus aureus mediated infections

The present study attempts to treat S. aureus-induced soft skin infections using a combinatorial therapy with an antibiotic, Ciprofloxacin (CIP), and an efflux pump inhibitor 5-Nitro-2-(3-phenylpropoxy) pyridine (5-NPPP) through a smart hydrogel delivery system. The study aims to reduce the increasing rates of infections and antimicrobial resistance; therefore, an efflux pump inhibitor molecule is synthesized and delivered along with an antibiotic to re-sensitize the pathogen towards antibiotics and treat the infections. CIP-loaded polyvinyl alcohol (PVA) hydrogels at varying concentrations were fabricated and optimized by a chemical cross-linking process, which exhibited sustained drug release for 5 days. The compound 5-NPPP loaded hydrogels provided linear drug release for 2 days, necessitating the need for the development of polymeric nanoparticles to alter the release drug pattern. 5-NPPP loaded Eudragit RSPO nanoparticles were prepared by modified nanoprecipitation-solvent evaporation method, which showed optimum average particle size of 230-280 nm with > 90% drug entrapment efficiency. The 5-NPPP polymeric nanoparticles loaded PVA hydrogels were fabricated to provide a predetermined sustained release of the compound to provide a synergistic effect. The selected 7% PVA hydrogels loaded with the dual drugs were evaluated using Balb/c mice models induced with S. aureus soft skin infections. The results of in vivo studies were evidence that the dual drugs loaded hydrogels were non-toxic and reduced the bacterial load causing re-sensitization towards antibiotics, which could initiate re-epithelization. The research concluded that the PVA hydrogels loaded with CIP and 5-NPPP nanoparticles could be an ideal and promising drug delivery system for treating S. aureus-induced skin infections.

Synthesis and Characterization of Ciprofloxacin Loaded Star-Shaped Polycaprolactone-Polyethylene Glycol Hydrogels for Oral Delivery

The administration of poorly water-soluble drugs represents a relevant problem due to the low body fluids transport efficiency through hydrophilic hydrogels. Star-shaped co-polymers, i.e., amphiphilic polymers such as those with a hydrophobic core and a hydrophilic outer shell, can be used to improve weak interactions with drugs, with relevant benefits in terms of administration and controlled delivery. In this work, two different co-polymers, four-arm star-shaped PCL-PEG and six-arm star-shaped PCL-PEG, were synthesized via ring-opening polymerization to be loaded with ciprofloxacin. ¹H-NMR and FTIR analyses confirmed that PCL arms were successfully grafted to the mPEG backbone, while DSC analysis indicated similar crystallinity and melting point, ranging from 56 to 60 °C, independent of the different co-polymer architecture. Therefore, both star-shaped PCL-PEGs were investigated as cargo device for ciprofloxacin. No significant differences were observed in terms of drug entrapment efficiency (>95%) and drug release, characterized by a pronounced burst followed by a slow sustained release, only slightly affected by the co-polymer architecture. This result was also confirmed with curve fitting via the Korsmeyer-Peppas model. Lastly, good antibacterial properties and biocompatibility exhibited in both star-shaped PCL-PEG co-polymers suggest a promising use for oral delivery applications.

Treatment of Periodontal Infections, the Possible Role of Hydrogels as Antibiotic Drug-Delivery Systems

With the advancement of biomedical research into antimicrobial treatments for various diseases, the source and delivery of antibiotics have attracted attention. In periodontal diseases, antibiotics are integral in positive treatment outcomes; however, the use of antibiotics is with caution as the potential for the emergence of resistant strains is of concern. Over the years, conventional routes of drug administration have been proven to be effective for the treatment of PD, yet the problem of antibiotic resistance to conventional therapies continues to remain a setback in future treatments. Hydrogels fabricated from natural and synthetic polymers have been extensively applied in biomedical sciences for the delivery of potent biological compounds. These polymeric materials either have intrinsic antibacterial properties or serve as good carriers for the delivery of antibacterial agents. The biocompatibility, low toxicity and biodegradability of some hydrogels have favoured their consideration as prospective carriers for antibacterial drug delivery in PD. This article reviews PD and its antibiotic treatment options, the role of bacteria in PD and the potential of hydrogels as antibacterial agents and for antibiotic drug delivery in PD. Finally, potential challenges and future directions of hydrogels for use in PD treatment and diagnosis are also highlighted.

Polymeric Based Hydrogel Membranes for Biomedical Applications

The development of biomedical applications is a transdisciplinary field that in recent years has involved researchers from chemistry, pharmacy, medicine, biology, biophysics, and biomechanical engineering. The fabrication of biomedical devices requires the use of biocompatible materials that do not damage living tissues and have some biomechanical characteristics. The use of polymeric membranes, as materials meeting the above-mentioned requirements, has become increasingly popular in recent years, with outstanding results in tissue engineering, for regeneration and replenishment of tissues constituting internal organs, in wound healing dressings, and in the realization of systems for diagnosis and therapy, through the controlled release of active substances. The biomedical application of hydrogel membranes has had little uptake in the past due to the toxicity of cross-linking agents and to the existing limitations regarding gelation under physiological conditions, but now it is proving to be a very promising field This review presents the important technological innovations that the use of membrane hydrogels has promoted, enabling the resolution of recurrent clinical problems, such as post-transplant rejection crises, haemorrhagic crises due to the adhesion of proteins, bacteria, and platelets on biomedical devices in contact with blood, and poor compliance of patients undergoing long-term drug therapies.

Composite Hydrogels with Included Solid-State Nanoparticles Bearing Anticancer Chemotherapeutics

Hydrogels have many useful physicochemical properties which, in combination with their biocompatibility, suggest their application as a drug delivery system for the local and prorogated release of drugs. However, their drug-absorption capacity is limited because of the gel net's poor adsorption of hydrophilic molecules and in particular, hydrophobic molecules. The absorption capacity of hydrogels can be increased with the incorporation of nanoparticles due to their huge surface area. In this review, composite hydrogels (physical, covalent and injectable) with included hydrophobic and hydrophilic nanoparticles are considered as suitable for use as carriers of anticancer chemotherapeutics. The main focus is given to the surface properties of the nanoparticles (hydrophilicity/hydrophobicity and surface electric charge) formed from metal and dielectric substances: metals (gold, silver), metal-oxides (iron, aluminum, titanium, zirconium), silicates (quartz) and carbon (graphene). The physicochemical properties of the nanoparticles are emphasized in order to assist researchers in choosing appropriate nanoparticles for the adsorption of drugs with hydrophilic and hydrophobic organic molecules.

Hydrophobic Drug Carrier from Polycaprolactone-b-Poly(Ethylene Glycol) Star-Shaped Polymers Hydrogel Blend as Potential for Wound Healing Application

Blending hydrogel with an amphiphilic polymer can increase the hydrophobic drug loading and entrapment efficiency of hydrogel-based formulations. In this study, a hydrogel formulation with star-shaped polycaprolactone-b-poly(ethylene glycol) (PCL-b-PEG) as the hydrophobic drug cargo is produced. The 4-arm and 6-arm star-shaped PCL are synthesized with different molecular weights (5000, 10,000, 15,000 g/mol) via ROP and MPEG as the hydrophilic segment is attached via the Steglich esterification. FTIR and ¹H-NMR analysis showed the presence of all functional groups for homopolymers and copolymers. M_n for all synthesized polymers is close to the theoretical value while GPC spectra showed a monomodal peak with narrow molecular weight distribution (PDI:1.01-1.25). The thermal degradation temperature and crystalline melting point of synthesized polymers increase with the increase in molecular weight and number of arms. All formulations possess high drug loading and entrapment efficiency (>99%) and increase with increasing molecular weight, number of arms, and amount of polymer in the formulations. All formulations showed a sustained drug release pattern with no initial burst, which follows the Korsmeyer-Peppas kinetic model. The polymer hydrogel formulations showed antibacterial activity against E. coli and S. aureus. The hydrogel containing 4-arm PCL_15k-PEG is chosen as the best formulation due to its high drug release, good antimicrobial activity, and morphology.

Gemini surfactant-like peptide-based nanocages with β-sheet-enhanced stability and encapsulation efficiency of hydrophobic anticancer drugs

Peptide-based scaffolds have been widely applied to drug delivery because of their ease and high yields of synthesis, well-defined structure, biocompatibility, diversity, tunability of properties, and molecular recognition abilities. However, the stability of peptide-based nanostructures highly depends on the intermolecular assembling manner, e.g., α-helix based coiled coils, β-sheet. Inspired by the robust protein fibril structures in amyloidosis, herein we constructed a β-sheet-forming gemini surfactant-like peptide to self-assemble into nanocages with the help of molecular dynamics simulation. As expected, the experimental results showed that nanocages can be formed with the inner diameter of up to ∼400 nm, which were robust enough even under both transmission electron microscopy and atomic force microscopy, indicating the significant contribution of β-sheet conformation. The β-nanocages can load hydrophobic anticancer drugs, e.g., paclitaxel with a very high encapsulation efficiency, which holds great potential for clinic drug delivery due to the improved anticancer effect as compared with paclitaxel alone.

Green synthesized polyvinylpyrrolidone/titanium dioxide hydrogel nanocomposite modified with agarose macromolecules for sustained and pH-responsive release of anticancer drug

Cancer, as one of the most challenging diseases of the last century, has a significant number of patients and deaths every year. Various strategies have been explored for the treatment of cancer. Chemotherapy is one of the methods of treating cancer. Doxorubicin is one of the compounds used in chemotherapy to kill cancer cells. Due to their unique properties and low toxicity, metal oxide nanoparticles are effective in combination therapy and increase the effectiveness of anti-cancer compounds. The limited in vivo circulatory period, poor solubility, and inadequate penetration of doxorubicin (DOX) restrict its use in cancer treatment, notwithstanding its attractive characteristics. It is possible to circumvent some of the difficulties in cancer therapy by using green synthesized pH-responsive nanocomposite consisting of polyvinylpyrrolidone (PVP), titanium dioxide (TiO₂) modified with agarose (Ag) macromolecules. TiO₂ incorporation into the PVP-Ag nanocomposite resulted in limited increased loading and encapsulation efficiencies from 41 % to 47 % and 84 % to 88.5 %, respectively. DOX diffusion among normal cells is prevented by the PVP-Ag-TiO₂ nanocarrier at pH = 7.4, though the acidic intracellular microenvironments activate the PVP-Ag-TiO₂ nanocarrier at pH = 5.4. Characterization of the nanocarrier was performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrophotometry, field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), and zeta potential. The average particle size and the zeta potential of the particles showed values of 349.8 nm and +57 mV, respectively. In vitro release after 96 h showed a release rate of 92 % at pH 7.4 and a release rate of 96 % at pH 5.4. Meanwhile, the initial release after 24 h was 42 % for pH 7.4 and 76 % for pH 5.4. As shown by an MTT analysis on MCF-7 cells, the toxicity of DOX-loaded PVP-Ag-TiO₂ nanocomposite was substantially greater than that of unbound DOX and PVP-Ag-TiO₂. After integrating TiO₂ nanomaterials into the PVP-Ag-DOX nanocarrier, flow cytometry data showed a greater stimulation of cell death. These data indicate that the DOX-loaded nanocomposite is a suitable alternative for drug delivery systems.

Chitosan Hydrogels Cross-Linked with Trimesic Acid for the Delivery of 5-Fluorouracil in Cancer Therapy

Chitosan exhibits unique properties making it a suitable material for drug delivery. Considering the rising popularity of hydrogels in this field, this work offers a comprehensive study of hydrogels constituted by chitosan and cross-linked with 1,3,5-benzene tricarboxylic acid (BTC; also known as trimesic acid). Hydrogels were prepared by cross-linking chitosan with BTC in different concentrations. The nature of the gels was studied through oscillatory amplitude strain and frequency sweep tests within the linear viscoelastic region (LVE) limit. The flow curves of the gels revealed shear thinning behavior. High G′ values imply strong cross-linking with improved stability. The rheological tests revealed that the strength of the hydrogel network increased with the cross-linking degree. Hardness, cohesiveness, adhesiveness, compressibility, and elasticity of the gels were determined using a texture analyzer. The scanning electron microscopy (SEM) data of the cross-linked hydrogels showed distinctive pores with a pore size increasing according to increasing concentrations (pore size range between 3–18 µm). Computational analysis was performed by docking simulations between chitosan and BTC. Drug release studies employing 5-fluorouracil (5-FU) yielded a more sustained release profile with 35 to 50% release among the formulations studied in a 3 h period. Overall, this work demonstrated that the presence of BTC as cross-linker leads to satisfactory mechanical properties of the chitosan hydrogel, suggesting potential applications in the sustained release of cancer therapeutics.

Newly developed nano-biocomposite embedded hydrogel to enhance drug loading and modulated release of anti-inflammatory drug

A newly developed iron-based nano-biocomposite (nano Fe-CNB) impregnated alginate formulation (CA) is proposed to improve drug loading and exhibit pH-responsive behavior of model anti-inflammatory drug-ibuprofen for controlled release applications. The proposed formulation is investigated with conventional β-CD addition in CA. The nano Fe-CNB-based formulations with and without β-CD, (Fe-CNB β-CD CA and Fe-CNB CA) are compared with only CA and β-CD incorporated CA formulations. The results indicate the incorporation of nano-biocomposite or β-CD into CA enhances the drug loading (>40%). However, pH-responsive controlled release behavior is observed for nano Fe-CNB based formulations only. The release studies from Fe-CNB β-CD CA indicate ∼ 45% release in stomach pH (1.2) within 2 h. In contrast, Fe-CNB CA shows ∼20% release only in stomach pH and improved release (∼49%) at colon pH (7.4). The rheology and swelling studies indicate Fe-CNB CA remains intact in stomach pH with a minimal drug release, but it disintegrates at colon pH due to charge reversal behavior of nano-biocomposite and ionization of polymeric chains. Thus, Fe-CNB CA formulation is found to be a potential candidate for targeting colon delivery, inflammatory bowel disease, and post-operative conditions.

Preparation of polymer nanoparticle-based complex coacervate hydrogels using polymerisation-induced self-assembly derived nanogels

This paper reports a generic method to prepare polymer nanoparticle-based complex coacervate (PNCC) hydrogels by employing rationally designed nanogels synthesised by reversible addition-fragmentation chain-transfer (RAFT)-mediated polymerisation-induced self-assembly (PISA). Specifically, a poly(potassium 3-sulfopropyl methacrylate) (PKSPMA) macromolecular chain-transfer agent (macro-CTA) was synthesised via RAFT solution polymerisation followed by chain-extension with a statistical copolymer of benzyl methacrylate (BzMA) and methacrylic acid (MAA) at pH 2. Thus, pH-responsive nanoparticles (NPs) comprising a hydrophobic polyacid core-forming block and a sulfonate-functional stabiliser block were formed. With the introduction of methacrylic acid into the core of the NPs, they become swollen with increasing pH, as judged by dynamic light scattering (DLS), indicating nanogel-type behaviour. PNCC hydrogels were prepared by simply mixing the PISA-derived nanogels and cationic branched polyethyleneimine (bPEI) at 20% w/w. In the absence of MAA in the core of the NPs, gel formation was not observed. The mass ratio between the nanogels and bPEI affected resulting hydrogel strength and a mixture of bPEI and PKSPMA₆₈-P(BzMA_0.6-stat-MAA_0.4)₃₀₀ NPs with a mass ratio of 0.14 at pH ∼7 resulted in a hydrogel with a storage modulus of approximately 2000 Pa, as determined by oscillatory rheology. This PNCC hydrogel was shear-thinning and injectable, with recovery of gel strength occurring rapidly after the removal of shear.

Injectable Thermosensitive Nanocomposites Based on Poly(N-vinylcaprolactam) and Silica Particles for Localized Release of Hydrophilic and Hydrophobic Drugs

The systemic delivery of drugs employed by conventional methods has shown to be less effective than a localized delivery system. Many drugs have the effectiveness reduced by fast clearance, increasing the amount required for an efficient treatment. One way to overcome this drawback is through the use of thermoresponsive polymers that undergo a sol-gel transition at physiological temperature, allowing their injection directly in the desired site. In this work, thermosensitive nanocomposites based on poly(N-vinylcaprolactam) and silica particles with 80 and 330 nm were synthesized to be employed as delivery systems for hydrophobic (naringin) and hydrophilic (doxorubicin hydrochloride) drugs. The insertion of SiO₂ increased the rheological properties of the nanocomposite at 37 °C, which helps to prevent its diffusion away from the site of injection. The synthesized materials were also able to control the drug release for a period of 7 days under physiological conditions. Due to its higher hydrophobicity and better interaction with the PNVCL matrix, naringin presented a more controlled release. The Korsmeyer-Peppas model indicated different release mechanisms for each drug. At last, a preliminary in vitro study of DOX-loaded nanocomposites cultured with L929 and MB49 cells showed negligible toxic effects on healthy cells and better efficient inhibition of carcinoma cells.

An Overview of Polymeric Nanoparticles-Based Drug Delivery System in Cancer Treatment

Cancer is recognized as one of the world's deadliest diseases, with more than 10 million new cases each year. Over the past 2 decades, several studies have been performed on cancer to pursue solutions for effective treatment. One of the vital benefits of utilizing nanoparticles (NPs) in cancer treatment is their high adaptability for modification and amalgamation of different physicochemical properties to boost their anti-cancer activity. Various nanomaterials have been designed as nanocarriers attributing nontoxic and biocompatible drug delivery systems with improved bioactivity. The present review article briefly explained various types of nanocarriers, such as organic-inorganic-hybrid NPs, and their targeting mechanisms. Here a special focus is given to the synthesis, benefits, and applications of polymeric NPs (PNPs) involved in various anti-cancer therapeutics. It has also been discussed about the drug delivery approach by the functionalized/encapsulated PNPs (without/with targeting ability) that are being applied in the therapy and diagnostic (theranostics). Overall, this review can give a glimpse into every aspect of PNPs, from their synthesis to drug delivery application for cancer cells.

Biomembrane-Based Nanostructure- and Microstructure-Loaded Hydrogels for Promoting Chronic Wound Healing

Wound healing is a complex and dynamic process, and metabolic disturbances in the microenvironment of chronic wounds and the severe symptoms they cause remain major challenges to be addressed. The inherent properties of hydrogels make them promising wound dressings. In addition, biomembrane-based nanostructures and microstructures (such as liposomes, exosomes, membrane-coated nanostructures, bacteria and algae) have significant advantages in the promotion of wound healing, including special biological activities, flexible drug loading and targeting. Therefore, biomembrane-based nanostructure- and microstructure-loaded hydrogels can compensate for their respective disadvantages and combine the advantages of both to significantly promote chronic wound healing. In this review, we outline the loading strategies, mechanisms of action and applications of different types of biomembrane-based nanostructure- and microstructure-loaded hydrogels in chronic wound healing.

Novel Injectable Fluorescent Polymeric Nanocarriers for Intervertebral Disc Application

Damage to intervertebral discs (IVD) can lead to chronic pain and disability, and no current treatments can fully restore their function. Some non-surgical treatments have shown promise; however, these approaches are generally limited by burst release and poor localization of diverse molecules. In this proof-of-concept study, we developed a nanoparticle (NP) delivery system to efficiently deliver high- and low-solubility drug molecules. Nanoparticles of cellulose acetate and polycaprolactone-polyethylene glycol conjugated with 1-oxo-1H-pyrido [2,1-b][1,3]benzoxazole-3-carboxylic acid (PBC), a novel fluorescent dye, were prepared by the oil-in-water emulsion. Two drugs, a water insoluble indomethacin (IND) and a water soluble 4-aminopyridine (4-AP), were used to study their release patterns. Electron microscopy confirmed the spherical nature and rough surface of nanoparticles. The particle size analysis revealed a hydrodynamic radius ranging ~150-162 nm based on dynamic light scattering. Zeta potential increased with PBC conjugation implying their enhanced stability. IND encapsulation efficiency was almost 3-fold higher than 4-AP, with release lasting up to 4 days, signifying enhanced solubility, while the release of 4-AP continued for up to 7 days. Nanoparticles and their drug formulations did not show any apparent cytotoxicity and were taken up by human IVD nucleus pulposus cells. When injected into coccygeal mouse IVDs in vivo, the nanoparticles remained within the nucleus pulposus cells and the injection site of the nucleus pulposus and annulus fibrosus of the IVD. These fluorescent nano-formulations may serve as a platform technology to deliver therapeutic agents to IVDs and other tissues that require localized drug injections.

Decoupling Individual Optical Nanosensor Responses Using a Spin-Coated Hydrogel Platform

Significant advances have been made in fields such as nanotechnology and biomedicine using the unique properties of single-walled carbon nanotubes (SWCNTs). Specifically, SWCNTs are used as near-infrared fluorescence sensors in the solution phase to detect a wide array of biologically relevant analytes. However, solution-based sensing has several limitations, including limited sensitivity and poor spatial resolution. We have therefore devised a new spin-coated poly(ethylene glycol) diacrylate (PEG-DA) hydrogel platform to examine individual DNA-functionalized SWCNTs (DNA-SWCNTs) in their native aqueous state and have subsequently used this platform to investigate the temporal modulations of each SWCNT in response to a model analyte. A strong surfactant, sodium deoxycholate (SDC), was chosen as the model analyte as it rapidly exchanges with DNA oligonucleotides on the SWCNT surface, modulating several optical properties of the SWCNTs and demonstrating multiparameter analyte detection. Upon addition of SDC, we observed time-dependent spectral modulations in the emission center wavelengths and peak intensities of the individual SWCNTs, indicative of a DNA-to-surfactant exchange process. Interestingly, we found that the modulations in the peak intensities, as determined by kinetic data, were significantly delayed when compared to their center wavelength counterparts, suggesting a potential decoupling of the response of these two spectral features. We used a 1-D diffusion model to relate the local SDC concentration to the spectral response of each SWCNT and created dose-response curves. The peak intensity shifts at a higher SDC concentration than the center wavelength, indicating a potential change in the conformation of the surfactant molecules adsorbed to the SWCNT sidewall after the initial exchange process. This platform allows for a unique single-molecule analysis technique that is significantly more sensitive and modifiable than utilizing SWCNTs in the solution phase.

Thiolated Polymeric Hydrogels for Biomedical Applications: A Review

Hydrogels are a three-dimensional (3D) network of hydrophilic polymers. The physical and chemical crosslinking of polymeric chains maintains the structure of the hydrogels even when they are swollen in water. They can be modified with thiol by thiol epoxy, thiol-ene, thiol-disulfide, or thiol-one reactions. Their application as a matrix for protein and drug delivery, cellular immobilization, regenerative medicine, and scaffolds for tissue engineering was initiated in the early 21st century. This review focuses on the ingredients, classification techniques, and applications of hydrogels, types of thiolation by different thiol-reducing agents, along with their mechanisms. In this study, different applications for polymers used in thiolated hydrogels, including dextran, gelatin, polyethylene glycol (PEG), cyclodextrins, chitosan, hyaluronic acid, alginate, poloxamer, polygalacturonic acid, pectin, carrageenan gum, arabinoxylan, carboxymethyl cellulose (CMC), gellan gum, and polyvinyl alcohol (PVA) are reviewed.

Insight into RNA-based Therapies for Ovarian Cancer

Ovarian cancer (OC) is one of the most common malignancies in women and is associated with poor outcomes. The treatment for OC is often associated with resistance to therapies and hence this has stimulated the search for alternative therapeutic approaches, including RNA-based therapeutics. However, this approach has some challenges that include RNA degradation. To solve this critical issue, some novel delivery systems have been proposed. In current years, there has been growing interest in the improvement of RNAbased therapeutics as a promising approach to target ovarian cancer and improve patient outcomes. This paper provides a practical insight into the use of RNA-based therapeutics in ovarian cancers, highlighting their potential benefits, challenges, and current research progress. RNA-based therapeutics offer a novel and targeted approach to treat ovarian cancer by exploiting the unique characteristics of RNA molecules. By targeting key oncogenes or genes responsible for drug resistance, siRNAs can effectively inhibit tumor growth and sensitize cancer cells to conventional therapies. Furthermore, messenger RNA (mRNA) vaccines have emerged as a revolutionary tool in cancer immunotherapy. MRNA vaccines can be designed to encode tumor-specific antigens, stimulating the immune system to distinguish and eliminate ovarian cancer cells. A nano-based delivery platform improves the release of loaded RNAs to the target location and reduces the off-target effects. Additionally, off-target effects and immune responses triggered by RNA molecules necessitate careful design and optimization of these therapeutics. Several preclinical and clinical researches have shown promising results in the field of RNA-based therapeutics for ovarian cancer. In a preclinical study, siRNA-mediated silencing of the poly (ADP-ribose) polymerase 1 (PARP1) gene, involved in DNA repair, sensitized ovarian cancer cells to PARP inhibitors, leading to enhanced therapeutic efficacy. In clinical trials, mRNA-based vaccines targeting tumor-associated antigens have demonstrated safety and efficacy in stimulating immune responses in ovarian cancer patients. In aggregate, RNA-based therapeutics represent a promising avenue for the therapy of ovarian cancers. The ability to specifically target oncogenes or stimulate immune responses against tumor cells holds great potential for improving patient outcomes. However, further research is needed to address challenges related to delivery, permanence, and off-target effects. Clinical trials assessing the care and effectiveness of RNAbased therapeutics in larger patient cohorts are warranted. With continued advancements in the field, RNAbased therapeutics have the potential to develop the management of ovarian cancer and provide new hope for patients.

Smart bioadhesives for wound healing and closure

The high demand for rapid wound healing has spurred the development of multifunctional and smart bioadhesives with strong bioadhesion, antibacterial effect, real-time sensing, wireless communication, and on-demand treatment capabilities. Bioadhesives with bio-inspired structures and chemicals have shown unprecedented adhesion strengths, as well as tunable optical, electrical, and bio-dissolvable properties. Accelerated wound healing has been achieved via directly released antibacterial and growth factors, material or drug-induced host immune responses, and delivery of curative cells. Most recently, the integration of biosensing and treatment modules with wireless units in a closed-loop system yielded smart bioadhesives, allowing real-time sensing of the physiological conditions (e.g., pH, temperature, uric acid, glucose, and cytokine) with iterative feedback for drastically enhanced, stage-specific wound healing by triggering drug delivery and treatment to avoid infection or prolonged inflammation. Despite rapid advances in the burgeoning field, challenges still exist in the design and fabrication of integrated systems, particularly for chronic wounds, presenting significant opportunities for the future development of next-generation smart materials and systems.

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Rational material engineering of bioadhesives with optimized mechanical and curative properties.

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Incorporation of biosensing allows real-time and precise evaluation of the healing stage.

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Closed-loop, smart bioadhesives that integrate wireless sensing and treatment hold great potential for chronic wound healing.

Investigation of the Sorption Capacity of Polyvinylpyrrolidone Copolymers As the Basis of Hydrogel Cosmetic Masks with Plant Biomass Extracts

The possibility of using hydrogels based on copolymers of polyvinylpyrrolidone with 2 hydroxyethylmethacrylate to saturate them with plant extracts was established. Hydrogel materials were obtained with extracts of Calendula officinalis and Arnica montana. The sorption capacity of the hydrogels regarding the extract data was determined. The bactericidal and fungicidal activity of the obtained hydrogel materials with extracts of Calendula officinalis and Arnica montana on bacterial strains of Escherichia coli, Staphylococcus aureus and fungal strains of Candida tenuis, Aspergilus niger were investigated.

Intervertebral Disk Regeneration in a Rat Model via a Nanocomposite Collagen Hydrogel Loaded with Galanthus Extract: An In Vitro and In Vivo Study

In the current study, Galanthus extract was loaded into electrospun gelatin scaffolds using an electrospun method and then crushed. The resulting nanofibers were loaded into a collagen hydrogel to develop a filler material to treat nucleus pulposus injuries in the intervertebral disks. The nanocomposite hydrogel was studied regarding its biocompatibility, antiinflammatory activity, and swelling behavior. In Vivo study was performed in a rat model of intervertebral disk injury. Histopathological studies showed that the animals treated with the nanocomposite hydrogel restored its nucleus pulposus to a significantly higher extent than other experimental groups.

Precise Design Strategies of Nanotechnologies for Controlled Drug Delivery

Rapid advances in nanotechnologies are driving the revolution in controlled drug delivery. However, heterogeneous barriers, such as blood circulation and cellular barriers, prevent the drug from reaching the cellular target in complex physiologic environments. In this review, we discuss the precise design of nanotechnologies to enhance the efficacy, quality, and durability of drug delivery. For drug delivery in vivo, drugs loaded in nanoplatforms target particular sites in a spatial- and temporal-dependent manner. Advances in stimuli-responsive nanoparticles and carbon-based drug delivery platforms are summarized. For transdermal drug delivery systems, specific strategies including microneedles and hydrogel lead to a sustained release efficacy. Moreover, we highlight the current limitations of clinical translation and an incentive for the future development of nanotechnology-based drug delivery.

Preparation of a pH‐responsive chitosan‐montmorillonite‐nitrogen‐doped carbon quantum dots nanocarrier for attenuating doxorubicin limitations in cancer therapy

Despite its widespread usage as a chemotherapy drug in cancer treatment, doxorubicin (DOX) has limitations such as short in vivo circulation time, low solubility, and poor permeability. In this regard, a pH‐responsive chitosan (CS)‐ montmorillonite (MMT)‐ nitrogen‐doped carbon quantum dots (NCQDs) nanocomposite was first developed, loaded with DOX, and then incorporated into a double emulsion to further develop the sustained release. The incorporated NCQDs into the CS‐MMT hydrogel exhibited enhanced loading and entrapment efficiencies. The presence of NCQDs nanoparticles in the CS‐MMT hydrogel also resulted in an extended pH‐responsive release of DOX over a period of 96 h compared to that of CS‐MMT‐DOX nanocarriers at pH 5.4. Based on the Korsmeyer‐Peppas model, there was a controlled DOX release at pH 5.4, while no diffusion was observed at pH 7.4, indicating fewer side effects. MTT assay showed that the cytotoxicity of DOX‐loaded CS‐MMT‐NCQDs hydrogel nanocomposite was significantly higher than those of free DOX (p < 0.001) and CS‐MMT‐NCQDs (p < 0.001) on MCF‐7 cells. Flow cytometry results demonstrated that a higher apoptosis induction achieved after incorporating NCQDs nanoparticles into CS‐MMT‐DOX nanocarrier. These findings suggest that the DOX‐loaded nanocomposite is a promising candidate for the targeted treatment of cancer cells.

A Comprehensive Review of Cross-Linked Gels as Vehicles for Drug Delivery to Treat Central Nervous System Disorders

Gels are attractive candidates for drug delivery because they are easily producible while offering sustained and/or controlled drug release through various mechanisms by releasing the therapeutic agent at the site of action or absorption. Gels can be classified based on various characteristics including the nature of solvents used during preparation and the method of cross-linking. The development of novel gel systems for local or systemic drug delivery in a sustained, controlled, and targetable manner has been at the epitome of recent advances in drug delivery systems. Cross-linked gels can be modified by altering their polymer composition and content for pharmaceutical and biomedical applications. These modifications have resulted in the development of stimuli-responsive and functionalized dosage forms that offer many advantages for effective dosing of drugs for Central Nervous System (CNS) conditions. In this review, the literature concerning recent advances in cross-linked gels for drug delivery to the CNS are explored. Injectable and non-injectable formulations intended for the treatment of diseases of the CNS together with the impact of recent advances in cross-linked gels on studies involving CNS drug delivery are discussed.

Antimicrobial effects of hydroxyapatite mosaicked polyvinyl alcohol-alginate semi-interpenetrating hydrogel-loaded with ethanolic extract of Glycyrrhiza glabra against oral pathogens

Glycyrrhiza glabra (GG) elicits protective effects against periodontal diseases. However, the sustained bioavailability of GG extract at therapeutic concentration warrants ideal delivery vehicles. Present study has focused on the design, fabrication, and evaluations of ethanolic-crude extract of GG-loaded semi-interpenetrating network (semi-IPN) hydrogel (HAAPS-GG) using alginic acid and polyvinyl alcohol (PVA) hydrogel mosaicked with HA for periodontal regeneration. The study has examined the performance of the hydrogel against the selected oral pathogens S. mutans, E. faecalis, L. acidophilus and C. albicans. HAAPS-GG was successfully fabricated and the surface functional groups were confirmed by attenuated total reflectance-infrared (ATR-IR) spectroscopy. HAAPS-GG displayed interconnecting pores, hydrophilicity and excellent water profile contributing to the biocompatibility as evident from direct contact and MTT assay in L929 fibroblasts. The hydrogel was mechanically stable and was immunocompatible owing to the relatively decreased levels of pro-inflammatory mediators COX2, 5LPO, iNOS and MPO in RAW 264.7 macrophages. In addition, the transcript analysis on RAW 264.7 revealed the down-regulation of inflammatory transcription factor NF-κβ and the pro-inflammatory cytokine TNF-α. Importantly, HAAPS-GG arrested the progression of periodontal pathogens predominantly S. mutans, and C. albicans as evident by disc diffusion assay, MTT assay and confocal microscopy. Overall, the HAAPS-GG system offers promising translational avenues in periodontal regeneration.

Biodegradable core-multishell nanocarrier: Topical tacrolimus delivery for treatment of dermatitis

Two challenges in topical drug delivery to the skin include solubilizing hydrophobic drugs in water-based formulations and increasing drug penetration into the skin. Polymeric core-multishell nanocarrier (CMS), particularly the novel biodegradable CMS (bCMS = hPG-PCL_1.1K-mPEG_2k-CMS) have shown both advantages on excised skin ex vivo. Here, we investigated topical delivery of tacrolimus (TAC; > 500 g/mol) by bCMS in a hydrogel on an oxazolone-induced model of dermatitis in vivo. As expected, bCMS successfully delivered TAC into the skin. However, in vivo they did not increase, but decrease TAC penetration through the stratum corneum compared to ointment. Differences in the resulting mean concentrations were mostly non-significant in the skin (epidermis: 35.7 ± 20.9 ng/cm² for bCMS vs. 92.6 ± 62.7 ng/cm² for ointment; dermis: 76.8 ± 26.8 ng/cm²vs 118.2 ± 50.4 ng/cm²), but highly significant in blood (plasma: 1.1 ± 0.4 ng/ml vs 11.3 ± 9.3 ng/ml; erythrocytes: 0.5 ± 0.2 ng/ml vs 3.4 ± 2.4 ng/ml) and liver (0.01 ± 0.01 ng/mg vs 0.03 ± 0.01 ng/mg). bCMS were detected in the stratum corneum but not in viable skin or beyond. The therapeutic efficacy of TAC delivered by bCMS was equivalent to that of standard TAC ointment. Our results suggest that bCMS may be a promising carrier for the topical delivery of TAC. The quantitative difference to previous results should be interpreted in light of structural differences between murine and human skin, but highlights the need as well as potential methods to develop more a complex ex vivo analysis on human skin to ensure quantitative predictive value.