Nanoscale poly(acrylic acid)-based hydrogels prepared via a green single-step approach for application as low-viscosity biomimetic fluid tears

Nanogels-Innovative Drug Carriers for Overcoming Biological Membranes

Nanogels are promising drug delivery systems since they possess undeniable advantages such as high loading capacity for hydrophilic and hydrophobic drugs, stabilization of sensitive drugs, biocompatibility, and biodegradability. The present review summarizes experimental studies related to carriers, drug loading, and membrane transport of nanogels. In particular, the review discusses the properties, advantages, and limitations of polymeric carriers with respect to the behavior of the prepared nanogels in in vivo conditions. The potential of nanogel systems for encapsulation of hydrophilic or hydrophobic drugs and the mechanisms of loading and drug release are also emphasized. Moreover, the challenges related to nanogel transport through the barriers presented in parenteral, oral, ocular, nasal, and dermal routes of administration are also considered.

Dexamethasone-loaded ROS stimuli-responsive nanogels for topical ocular therapy of corneal neovascularization

Dexamethasone (DEX) has been demonstrated to inhibit the inflammatory corneal neovascularization (CNV). However, the therapeutic efficacy of DEX is limited by the poor bioavailability of conventional eye drops and the increased risk of hormonal glaucoma and cataract associated with prolonged and frequent usage. To address these limitations, we have developed a novel DEX-loaded, reactive oxygen species (ROS)-responsive, controlled-release nanogel, termed DEX@INHANGs. This advanced nanogel system is constructed by the formation of supramolecular host-guest complexes by cyclodextrin (CD) and adamantane (ADA) as a cross-linking force. The introduction of the ROS-responsive material, thioketal (TK), ensures the controlled release of DEX in response to oxidative stress, a characteristic of CNV. Furthermore, the nanogel's prolonged retention on the corneal surface for over 8 h is achieved through covalent binding of the integrin β1 fusion protein, which enhances its bioavailability. Cytotoxicity assays demonstrated that DEX@INHANGs was not notably toxic to human corneal epithelial cells (HCECs). Furthermore, DEX@INHANGs has been demonstrated to effectively inhibit angiogenesis in vitro. In a rabbit model with chemically burned eyes, the once-daily topical application of DEX@INHANGs was observed to effectively suppress CNV. These results collectively indicate that the nanomedicine formulation of DEX@INHANGs may offer a promising treatment option for CNV, offering significant advantages such as reduced dosing frequency and enhanced patient compliance.

ThermOxshield ion pair self assembly unleashing suppressed release

Poly (acrylic acid) (PAA), an anionic polymer was used to prepare ion pair self-assembly (IPSAM) with 4-(methylthio)aniline (MTA), a hydrophobic counter ion, which is responsive to temperature and oxidation. The IPSAM was formed when the carboxylic to amino group molar ratio was 7/3-5/5. The structure of the IPSAM nanoparticle was spherical whose diameter was 30-40 nm on the TEM images. The PAA/MTA ion pair showed the upper critical solution temperature (UCST) that hiked with increasing MTA content. When the MTA of the ion pair was oxidized by H2O2, the UCST was also increased. The amphiphilic property of the ion pair was responsible for interface activity which declined upon the oxidation of the MTA. The surface tension was low for the ratio of PAA/MTA (5/5), which made the 5/5 ratio suitable for further studies. The interaction between PAA and MTA, which was ionic, and the oxidation of MTA was confirmed by FT-IR spectroscopy. The release of payload (i.e. Nile red) in IPSAM was restrained below the UCST but it was triggered above the phase transition temperature possibly due to the disintegration of the IPSAM whereas on MTA oxidation the release was shielded due to more hydrophobicity. The release was found to be higher in tumor environment temperature which could be controlled with the input concentration of H2O2 giving a stable IPSAM. The cell viability results showed that IPSAM has no significant cytotoxicity and can serve as a drug carrier for stimulus-response.

Developments in Emerging Topical Drug Delivery Systems for Ocular Disorders

According to the current information, using nano gels in the eyes have therapeutic benefits. Industry growth in the pharmaceutical and healthcare sectors has been filled by nanotechnology. Traditional ocular preparations have a short retention duration and restricted drug bioavailability because of the eye's architectural and physiological barriers, a big issue for physicians, patients, and chemists. In contrast, nano gels can encapsulate drugs within threedimensional cross-linked polymeric networks. Because of their distinctive structural designs and preparation methods, they can deliver loaded medications in a controlled and sustained manner, enhancing patient compliance and therapeutic efficacy. Due to their excellent drugloading capacity and biocompatibility, nano-gels outperform other nano-carriers. This study focuses on using nano gels to treat eye diseases and provides a brief overview of their creation and response to stimuli. Our understanding of topical drug administration will be advanced using nano gel developments to treat common ocular diseases such as glaucoma, cataracts, dry eye syndrome, bacterial keratitis, and linked medication-loaded contact lenses and natural active ingredients.

Advances in Nanogels for Topical Drug Delivery in Ocular Diseases

Nanotechnology has accelerated the development of the pharmaceutical and medical technology fields, and nanogels for ocular applications have proven to be a promising therapeutic strategy. Traditional ocular preparations are restricted by the anatomical and physiological barriers of the eye, resulting in a short retention time and low drug bioavailability, which is a significant challenge for physicians, patients, and pharmacists. Nanogels, however, have the ability to encapsulate drugs within three-dimensional crosslinked polymeric networks and, through specific structural designs and distinct methods of preparation, achieve the controlled and sustained delivery of loaded drugs, increasing patient compliance and therapeutic efficiency. In addition, nanogels have higher drug-loading capacity and biocompatibility than other nanocarriers. In this review, the main focus is on the applications of nanogels for ocular diseases, whose preparations and stimuli-responsive behaviors are briefly described. The current comprehension of topical drug delivery will be improved by focusing on the advances of nanogels in typical ocular diseases, including glaucoma, cataracts, dry eye syndrome, and bacterial keratitis, as well as related drug-loaded contact lenses and natural active substances.

Biopolymers in Mucoadhesive Eye Drops for Treatment of Dry Eye and Allergic Conditions: Application and Perspectives

Dry eye syndrome and allergic conjunctivitis are the most common inflammatory disorders of the eye surface. Although eye drops are the most usual prescribed dosage form, they are characterized by low ocular availability due to numerous barrier mechanisms of the eye. The use of biopolymers in liquid ophthalmic preparations has numerous advantages, such as increasing the viscosity of the tear film, exhibiting bioadhesive properties, and resisting the drainage system, leading to prolonged retention of the preparation at the site of application, and improvement of the therapeutic effect. Some mucoadhesive polymers are multifunctional excipients, so they act by different mechanisms on increasing the permeability of the cornea. Additionally, many hydrophilic biopolymers can also represent the active substances in artificial tear preparations, due to their lubrication and moisturizing effect. With the modification of conventional ophthalmic preparations, there is a need for development of new methods for their characterization. Numerous methods for the assessment of mucoadhesiveness have been suggested by the literature. This review gives an overview related to the development of mucoadhesive liquid ophthalmic formulations for the treatment of dry eye and allergic conditions.

Biomaterials for dry eye disease treatment: Current overview and future perspectives

Dry eye disease (DED) is an emerging health problem affecting millions of individuals every year. The current treatments for DED include lubricating eye drops and anti-inflammatory agents. These agents have to be used frequently and contain preservatives, which can damage the ocular surface. A substantially long-acting treatment with better bioavailability on the ocular surface might reduce the frequency of drug use and its side effects. This review summarizes the current state of different biomaterials-nanosystems, hydrogels, and contact lenses used as drug delivery systems in DED. The explored drugs in biomaterial formulation are cyclosporin, ocular lubricants, and topical steroids. Most of the data is from animal models where increased drug delivery and desired therapeutic effects could be obtained; however, trials involving human participants are yet to happen. There is no published study comparing the different types of biomaterials for DED use. Long-term studies evaluating their ocular toxicity and biocompatibility would enhance their transition to human use. Overall they look promising for DED treatment, but they are still in the stage of technological advancement and clinical studies.

Recent Advances in Hydrogels for the Diagnosis and Treatment of Dry Eye Disease

Dry eye disease (DED) is the most common clinical ocular surface disease. Given its multifactorial etiology, no consensus has been reached on the diagnosis criteria for dry eye disease. Topical drug administration remains the mainstay of treatment but is limited to the rapid clearance from the eye surface. To address these problems, hydrogel-based materials were designed to detect biomarkers or act as drug delivery systems by taking advantage of their good biocompatibility, excellent physical and mechanical properties, and long-term implant stability. Biosensors prepared using biocompatible hydrogels can be sensitive in diagnosing DED, and the designed hydrogels can also improve the drug bioavailability and retention time for more effective and long-term treatment. This review summarizes recent advances in the use of hydrogels for diagnosing and treating dry eye, aiming to provide a novel reference for the eventual clinical translation of hydrogels in the context of dry eye disease.

Anti-Oxidative and Anti-Inflammatory Micelles: Break the Dry Eye Vicious Cycle

Dry eye disease (DED) impacts ≈30% of the world's population and causes serious ocular discomfort and even visual impairment. Inflammation is one core cause of the DED vicious cycle, a multifactorial deterioration in DED process. However, there are also reactive oxygen species (ROS) regulating inflammation and other points in the cycle from the upstream, leading to treatment failure of current therapies merely targeting inflammation. Accordingly, the authors develop micelle-based eye drops (more specifically p38 mitogen-activated protein kinases (MAPK) inhibitor Losmapimod (Los)-loaded and ROS scavenger Tempo (Tem)-conjugated cationic polypeptide micelles, designated as MTem/Los) for safe and efficient DED management. Cationic MTem/Los improve ocular retention of conjugated water-soluble Tem and loaded water-insoluble Los via electrostatic interaction with negatively charged mucin on the cornea, enabling an increase in therapeutic efficiency and a decrease in dosing frequency. Mechanistically, MTem/Los effectively decrease ROS over-production, reduce the expression of proinflammatory cytokines and chemokines, restrain macrophage proinflammatory phenotypic transformation, and inhibit cell apoptosis. Therapeutically, the dual-functional MTem/Los suppress the inflammatory response, reverse corneal epithelial defect, save goblet cell dysfunction, and recover tear secretion, thus breaking the vicious cycle and alleviating the DED. Moreover, MTem/Los exhibit excellent biocompatibility and tolerability for potential application as a simple and rapid treatment of oxidative stress- and inflammation-induced disorders, including DED.

Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications

Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.

Polyethylene oxide-polyacrylic acid-folic acid (PEO-PAAc) nanogel as a 99m Tc targeting receptor for cancer diagnostic imaging

Nanoparticles are frequently used as targeting delivery systems for therapeutic and diagnostic radiopharmaceuticals. Polyethylene oxide-polyacrylic acid (PEO-PAAc) nanogel was prepared via γ-radiation-induced polymerization. Variable factors affecting nanoparticles size were investigated. The nanogel was radiolabeled with the imaging radioisotope ^99m Tc and finally conjugated with folic acid to target folate receptor actively. PEO-PAAc-folic acid gel was characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM). Biodistribution was studied in normal mice and solid tumor-bearing mice via intravenous and intratumor injections of the radiolabeled PEO-PAAc-folic acid nanogel. Results of biodistribution showed high selective uptake of the prepared complex in tumor muscle compared with normal muscle for both intravenous and intratumor injections. The T/NT ratio was found to be 6.186 and 294.5 for intravenous and intratumor injections, respectively. Consequently, ^99m Tc-PEO-PAAc-folic acid complex could be a promising agent for cancer diagnostic imaging.

Radiation-Assisted Synthesis of Polymer-Based Nanomaterials

Radiation technology has long been proven as a simple, rapid, green and sustainable technology with macroscale applications in healthcare, industry and environment. Its merits, however, have not been fully utilized in today’s ever growing nanotechnology. Ionizing radiation has beneficial effects for the synthesis and modification of structure and properties of nanomaterials. This paper intends to update the application of ionizing radiation in the development of various nanomaterials under the categories: (i) carbon-based nanomaterials, (ii) metal-based nanomaterials, (iii) polymer-based nanomaterials, (iv) polymer nanocomposites and (v) nano-scale grafting for advanced membrane applications.

Activity of Povidone in Recent Biomedical Applications with Emphasis on Micro- and Nano Drug Delivery Systems

Due to the unwanted toxic properties of some drugs, new efficient methods of protection of the organisms against that toxicity are required. New materials are synthesized to effectively disseminate the active substance without affecting the healthy cells. Thus far, a number of polymers have been applied to build novel drug delivery systems. One of interesting polymers for this purpose is povidone, pVP. Contrary to other polymeric materials, the synthesis of povidone nanoparticles can take place under various condition, due to good solubility of this polymer in several organic and inorganic solvents. Moreover, povidone is known as nontoxic, non-carcinogenic, and temperature-insensitive substance. Its flexible design and the presence of various functional groups allow connection with the hydrophobic and hydrophilic drugs. It is worth noting, that pVP is regarded as an ecofriendly substance. Despite wide application of pVP in medicine, it was not often selected for the production of drug carriers. This review article is focused on recent reports on the role povidone can play in micro- and nano drug delivery systems. Advantages and possible threats resulting from the use of povidone are indicated. Moreover, popular biomedical aspects are discussed.

Why chitosan could be apt candidate for glaucoma drug delivery - An overview

Most of the people in the world are affected by glaucoma, which leads to irreversible blindness. Several patient friendly treatments are available, nevertheless medications lack an easy and efficient way of sustained delivery. To make the delivery with enhanced bioavailability, biodegradable and non-biodegradable polymers-based drug carriers are explored. However, ocular drug delivery issues have not been resolved yet due to less adhesiveness, poor penetration ability, pH, and temperature dependent burst releases. Chitosan is found to be effective for ocular drug delivery due to excellent physio-chemical properties in terms of overcoming the existing issues. In this review, we aim to highlight why it has been chosen and the holy grail for ocular drug delivery. Besides, we have comprehensively reviewed recent patents on chitosan as a platform for ocular drug delivery and future perspectives on factors, lacunae and challenges that need to be addressed for better ocular delivery methods for glaucoma management.

Micro- to Nanoscale Bio-Hybrid Hydrogels Engineered by Ionizing Radiation

Bio-hybrid hydrogels consist of a water-swollen hydrophilic polymer network encapsulating or conjugating single biomolecules, or larger and more complex biological constructs like whole cells. By modulating at least one dimension of the hydrogel system at the micro- or nanoscale, the activity of the biological component can be extremely upgraded with clear advantages for the development of therapeutic or diagnostic micro- and nano-devices. Gamma or e-beam irradiation of polymers allow a good control of the chemistry at the micro-/nanoscale with minimal recourse to toxic reactants and solvents. Another potential advantage is to obtain simultaneous sterilization when the absorbed doses are within the sterilization dose range. This short review will highlight opportunities and challenges of the radiation technologies to produce bio-hybrid nanogels as delivery devices of therapeutic biomolecules to the target cells, tissues, and organs, and to create hydrogel patterns at the nano-length and micro-length scales on surfaces.

Novel Poly(vinylpyrrolidone)-Coated Silicone Contact Lenses to Improve Tear Volume During Lens Wear: In Vitro and In Vivo Studies

Poly(vinylpyrrolidone) (PVP-K90) is widely used to manage dry eye syndrome (DES). The marketed eye drop solutions (high dose) need frequent instillation, affecting the routine lifestyle of patients. PVP-K90-laden contact lenses can be used to overcome the limitations of eye drop solutions (low bioavailability and frequent instillation). However, the conventional methods of PVP-K90 loading show poor loading capacity and short duration of effect. In the present study, we have developed PVP-K90-coated contact lenses via a short curing approach to increase the PVP-K90 loading capacity with a sustained release profile to manage dry eye syndrome. PVP-K90 was loaded by a soaking method (SM-PVP), direct loading (during fabrication, DL-PVP), a combination of soaking and direct loading (DL-SM-PVP), and a novel coating process (SM-PVP-C and DL-SM-PVP-C). The swelling studies suggested improvement in the water uptake (hydration) property of the contact lenses due to the presence of PVP-K90. The optical transparency was within an acceptable range. The in vitro release of PVP-K90 was in the following order: PVP-coated contact lens (168 h) > DL-SM-PVP (168 h) > DL-PVP (96 h) > SM-PVP (72-96 h). PVP-coated contact lenses showed a high burst effect (lubricating effect) and sustained release (3161-448 ng/h between 24 and 168 h) due to high PVP loading/coating in comparison to the uncoated respective contact lenses (964-113 ng/h between 24 and 96 h). In animal studies, the PVP-K90-coated contact lens showed higher tear volume in comparison to the respective uncoated contact lenses and an eye drop solution. This study demonstrates a novel approach of coating a high amount of PVP-K90 on contact lenses for sustained release to manage several ocular diseases like dry eye syndrome, conjunctivitis, and other ocular injuries.