Perspectives of Molecularly Imprinted Polymer-Based Drug Delivery Systems in Ocular Therapy

Unlocking New Avenues: Solid-State Synthesis of Molecularly Imprinted Polymers

Molecularly imprinted polymers (MIPs) are established artificial molecular recognition platforms with tailored selectivity towards a target molecule, whose synthesis and functionality are highly influenced by the nature of the solvent employed in their synthesis. Steps towards the "greenification" of molecular imprinting technology (MIT) has already been initiated by the elaboration of green MIT principles; developing MIPs in a solvent-free environment may not only offer an eco-friendly alternative, but could also significantly influence the affinity and expected selectivity of the resulting binding sites. In the current study the first solvent-free mechanochemical synthesis of MIPs via liquid-assisted grinding (LAG) is reported. The successful synthesis of the imprinted polymer was functionally demonstrated by measuring its template rebinding capacity and the selectivity of the molecular recognition process in comparison with the ones obtained by the conventional, non-covalent molecular imprinting process in liquid media. The results demonstrated similar binding capacities towards the template molecule and superior chemoselectivity compared to the solution-based MIP synthesis method. The adoption of green chemistry principles with all their inherent advantages in the synthesis of MIPs may not only be able to alleviate the potential environmental and health concerns associated with their analytical (e.g., selective adsorbents) and biomedical (e.g., drug carriers or reservoirs) applications, but might also offer a conceptual change in molecular imprinting technology.

Regulation of cell fate by cell imprinting approach in vitro

Cell culture-based technologies are widely utilized in various domains such as drug evaluation, toxicity assessment, vaccine and biopharmaceutical development, reproductive technology, and regenerative medicine. It has been demonstrated that pre-adsorption of extracellular matrix (ECM) proteins including collagen, laminin and fibronectin provide more degrees of support for cell adhesion. The purpose of cell imprinting is to imitate the natural topography of cell membranes by gels or polymers to create a reliable environment for the regulation of cell function. The results of recent studies show that cell imprinting is a tool to guide the behavior of cultured cells by controlling their adhesive interactions with surfaces. Therefore, in this review we aim to compare different cell cultures with the imprinting method and discuss different cell imprinting applications in regenerative medicine, personalized medicine, disease modeling, and cell therapy.

[Recent advances in the applications of metal-organic frameworks-based molecularly imprinted materials]

Molecularly imprinted polymers have received wide attention from various fields owing to their pre-designable, recognition ability, and practicality. However, the disadvantages of the traditional embedding method, which include a slow recognition rate, uneven site recognition, low binding capacity, and incomplete template molecule elution, limit the development of molecular imprinting technology. Surface molecular imprinting techniques have been developed to effectively solve these problems, and different materials are used as carriers in the synthesis of molecularly imprinted polymers. Metal-organic frameworks (MOFs) show great potential as carriers. Because of their high porosity and specific surface area, MOFs can provide a large number of active sites for molecular imprinting, which can improve their detection sensitivity. The variable metal centers and organic ligands of MOF materials can also lead to multiple structures and functions. Numerous types of MOF materials have been synthesized, and the properties of these materials can be tailored by adjusting their pore size and introducing functional groups. MOFs and molecular imprinting technology can be combined to take full advantage of the specific adsorption of molecular imprinting technology and the large specific surface area and multiple active sites of MOFs, thereby expanding the application range of the resulting materials. In this paper, five aspects of the concept of MOF functionalization are discussed: introduction of special ligands, regulation of metal central sites, formation of MOF complexes, derivatization of MOFs, and sacrificial MOFs. The applications of MOF-based molecularly imprinted materials in catalysis, sample pretreatment, drug carriers, fluorescence sensors, and electrochemical sensors are also reviewed. Finally, the existing problems and future development of MOF-based molecularly imprinted materials are discussed and prospected.

Polymeric micelles loaded in situ gel with prednisolone acetate for ocular inflammation: development and evaluation

Aim: Our study developed a prednisolone acetate polymeric micelles (PM) system for ocular inflammation related to allergic uveitis. Methods: For PM development, a thin-film hydration procedure was used. Irritation, in vitro, ex vivo transcorneal permeation, micelle size, entrapment efficiency and histology within the eye were all calculated for PM. Results: The optimized in situ gel (A4) showed superior ex vivo transcorneal permeation with zero-order kinetics. Conclusion: The developed formulation could be a promising candidate for treating anterior uveitis via topical application to the anterior segment of the eye.

Topical Treatment for Retinal Degenerative Pathologies: A Systematic Review

The topical administration of medicines is the preferred route in ocular therapy, at least for the anterior segment of the eye. However, the eye's inherent functional and biological barriers all work against the active pharmaceutical ingredient (API) to efficiently reach the targeted retinal structures. The main objective of this article is to offer a systematic review of the scientific literature in recent years, focusing on the latest developments of topical treatment intended for retinal degenerative diseases. Database search returned 102 clinical studies, focused on topical treatment for age macular degeneration, macular edemas (in diabetic retinopathy, surgery related or in retinal dystrophies) or glaucoma. After the exclusion of low-powered studies and those combining vitreo-retinal surgery, 35 articles remained for analysis. Currently, the topical treatment of retinal degenerative diseases is limited by the difficulty to deliver effective drug concentrations to the posterior eye structures. However, in the case of drug classes like NSAIDs, the presence of certain molecular and metabolic features for specific representatives makes the topical administration currently feasible in several clinical contexts. For other drug classes, either a fine-tuning of the API's pharmacokinetic profile or the use of more advanced formulation strategies, such as rationally designed nanostructured drugs and vehicles, crystalline polymorphs or supramolecular complexes, could bring the much awaited breakthrough for a more predictable and controlled delivery towards the retinal structures and could eventually be employed in the future for the development of more effective ways of delivering drugs to the posterior eye, with the ultimate goal of improving their clinical efficacy.

Ruxolitinib-Loaded Imprinted Polymeric Drug Reservoir for the Local Management of Post-Surgical Residual Glioblastoma Cells

(1) Background: The current limitations of glioblastoma (GBM) chemotherapy were addressed by developing a molecularly imprinted polymer (MIP)-based drug reservoir designed for the localized and sustained release of ruxolitinib (RUX) within the tumor post-resection cavity, targeting residual infiltrative cancerous cells, with minimum toxic effects toward normal tissue. (2) Methods: MIP reservoirs were synthesized by precipitation polymerization using acrylamide, trifluoromethacrylic acid, methacrylic acid, and styrene as monomers. Drug release profiles were evaluated by real-time and accelerated release studies in phosphate-buffered solution as a release medium. The cytotoxicity of polymers and free monomers was evaluated in vitro on GBM C6 cells using the Alamar Blue assay, optical microscopy, and CCK8 cell viability assay. (3) Results: Among the four synthesized MIPs, trifluoromethacrylic acid-based polymer (MIP 2) was superior in terms of loading capacity (69.9 μg RUX/mg MIP), drug release, and efficacy on GBM cells. Accelerated drug release studies showed that, after 96 h, MIP 2 released 42% of the loaded drug at pH = 7.4, with its kinetics fitted to the Korsmeyer-Peppas model. The cell viability assay proved that all studied imprinted polymers provided high efficacy on GBM cells. (4) Conclusions: Four different drug-loaded MIPs were developed and characterized within this study, with the purpose of obtaining a drug delivery system (DDS) embedded in a fibrin-based hydrogel for the local, post-surgical administration of RUX in GBM in animal models. MIP 2 emerged as superior to the others, making it more suitable and promising for further in vivo testing.

Molecularly Imprinted Nanomaterials with Stimuli Responsiveness for Applications in Biomedicine

The review aims to summarize recent reports of stimuli-responsive nanomaterials based on molecularly imprinted polymers (MIPs) and discuss their applications in biomedicine. In the past few decades, MIPs have been proven to show widespread applications as new molecular recognition materials. The development of stimuli-responsive nanomaterials has successfully endowed MIPs with not only affinity properties comparable to those of natural antibodies but also the ability to respond to external stimuli (stimuli-responsive MIPs). In this review, we will discuss the synthesis of MIPs, the classification of stimuli-responsive MIP nanomaterials (MIP-NMs), their dynamic mechanisms, and their applications in biomedicine, including bioanalysis and diagnosis, biological imaging, drug delivery, disease intervention, and others. This review mainly focuses on studies of smart MIP-NMs with biomedical perspectives after 2015. We believe that this review will be helpful for the further exploration of stimuli-responsive MIP-NMs and contribute to expanding their practical applications especially in biomedicine in the near future.

In Vivo Applications of Molecularly Imprinted Polymers for Drug Delivery: A Pharmaceutical Perspective

Molecularly imprinted polymers (MIPs) have been proven to be a promising candidate for drug delivery systems (DDS) due to their ability to provide a sustained and controlled drug release, making them useful for treating a wide range of medical conditions. MIP-based DDS offer many advantages, including the administration of a smaller drug doses, due to the higher drug payload or targeted delivery, resulting in fewer side effects, as well as the possibility of attaining high concentrations of the drug in the targeted tissues. Whether designed as drug reservoirs or targeted DDS, MIPs are of great value to drug delivery as conventional drug formulations can be redesigned as DDS to overcome the active pharmaceutical ingredient's (APIs) poor bioavailability, toxic effects, or other shortcomings that previously made them less efficient or unsuitable for therapy. Therefore, MIP design could be a promising alternative to the challenging research and development of new lead compounds. Research on MIPs is primarily conducted from a material science perspective, which often overlooks some of their key pharmaceutical requirements. In this review, we emphasize the specific features that make MIPs suitable for clinical use, from both a material science and a biopharmaceutical perspective.

Crosslinking-Dependent Drug Kinetics in Hydrogels for Ophthalmic Delivery

Drug-diffusion kinetics in 2-hydroxyethyl methacrylate hydrogels were studied as a function of the crosslinking density and porosity. By varying the concentration of the crosslinker, tetraethylene glycol dimethacrylate, we demonstrated how the release of Timolol maleate could be optimized to allow for efficient drug delivery. FTIR and spectrophotometry supplied optical inferences into the functional groups present. By studying the swelling and degradation of hydrogels, supplemented with drug-release kinetics studies, the relationship between these two tenets could be formulated.