A promising 'single' and 'dual' drug-nanocomposite enriched contact lens for the management of glaucoma in response to the tear fluid enzyme

Glaucoma is a neurodegenerative condition that results in the damage of retinal ganglion cells due to elevated intraocular pressure (IOP). To curtail the limitations associated with conventional treatments such as eye drops and ocular suspensions, we have developed 'single' and 'dual' drug delivery contact lenses (CLs), that is, latanoprost (LP) and latanoprost-timolol (LP-TM) deliverable CLs, in response to lysozyme (Lyz), which is abundant in the lacrimal fluid. Since chitosan (CS) can entrap more of the drug and also undergo hydrolysis in the presence of Lyz, we have employed CS for the composite preparation. The CL fabrication was performed by free radical copolymerization of poly(2-hydroxyethyl methacrylate) (pHEMA) in the presence of the drug-loaded nanocomposite with UV-curing initiators using the pre-drug loading strategy. The surface morphological, optical and mechanical investigations confirmed the presence of the drugs, ≥80% transparency, the adequate flexibility and biocompatibility of both the CLs. The in vitro release experiments showed the release of 95.86% LP from LP-CL, and 83.87% LP and 86.70% TM from LP-TM-CL in the presence of 1.5 mg mL-1 of Lyz in 72 h. In vitro biocompatibility assay against human corneal epithelial (HCE) cells and ex vivo experiments on HET-CAM confirmed that the fabricated LP-CL and LP-TM-CL are well tolerated. Moreover, in vivo safety evaluations of CLs on New Zealand white rabbit eyes suggest no sign of irritation to the ocular tissues within 72 h of observation. Hence, the study suggests that the 'single' and 'dual' drug-loaded CLs could open a new avenue to manage glaucoma by maintaining mean diurnal IOP.

Development of mucoadhesive Timolol loaded chitosan-nanocomposite to treat glaucoma

Timolol Maleate is an aqueous soluble β-blocker antiglaucoma drug used to suppress intraocular pressure. Several commercially available ocular formulations are not effective in delivering to the target site due to their water-soluble property and low mucoadhesiveness. Hence, there is a requirement for a highly mucoadhesive drug-loaded nanocomposite to suppress intraocular pressure with enhanced bioavailability. Herein, we have prepared a mucoadhesive Timolol-loaded graphene quantum dot-chitosan-nanocomposite to treat glaucoma in response to lysozyme, secreted in the tear fluid. The as-prepared nanocomposite has been characterized through high resolution-transmission electron microscopic, X-ray photoelectron spectroscopic, X-ray diffraction, and Fourier transform infrared spectral studies. The nanocomposite showed 93.74 % encapsulation efficiency with a loading capacity of 7.73 %. Further, 89.26 %, 95.62 %, and 99.29 % of drug release were observed from the nanocomposite in the presence of 1, 1.5, and 2 mg/mL of lysozyme. The mucoadhesion property has been confirmed by the increment in the particle size, fluorescence spectral variations, and Fourier transform infrared spectroscopic studies in the presence of mucin nanoparticles of size 291 nm. Interestingly, mucoadhesion has been demonstrated by pointing to the quenching in the luminescence of mucin. Further, in vitro biocompatibility assay on human corneal epithelial cells showed ≥80 % cell viability. Hence, this study offers the utilization of naturally secreting enzymes for drug delivery applications instead of uncontrolled pH and temperature-triggered releases.

In vivo application of magnetic molecularly imprinted polymer in rheumatoid arthritis rat model

A magnetic molecularly imprinted polymer (MMIP) was synthesised and tested for an in vivo rheumatoid arthritis (RA) rat model. Magnetite coated with mesoporous silica (Fe2O3@mSi) was used as core for surface imprinting, dopamine was used as monomer and methotrexate (MTX) was loaded directly during polymerisation. The amount of MTX loaded on MMIPs reached 201.165 ± 0.315 µmol/g. Characterisation of the polymers was done via SEM, TEM, and FTIR. The pharmacological effect of the selected MMIP was evaluated in a Complete Freund's Adjuvant (CFA) induced arthritis rat model where a 3D magnet bearing construct was designed for targeted delivery of MMIPs. The parameters evaluated were the change in paw edoema, paw diameter, gait score, and animal's weight. Results revealed a tendency of MMIP to significantly improve the measured parameters which was confirmed with histopathological findings. In conclusion, the improvement in the arthritic signs associated with MMIP treatment compared to free MTX, indicated successful targeting of MMIPs to the site of inflammation.

Polytyramine Film-Coated Single-Walled Carbon Nanotube Electrochemical Chemosensor with Molecularly Imprinted Polymer Nanoparticles for Duloxetine-Selective Determination in Human Plasma

We devised, fabricated, and tested differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) chemosensors for duloxetine (DUL) antidepressant determination in human plasma. Polyacrylic nanoparticles were synthesized by precipitation polymerization and were molecularly imprinted with DUL (DUL-nanoMIPs). Then, together with the single-walled carbon nanotube (SWCNT) scaffolds, they were uniformly embedded in polytyramine films, i.e., nanoMIPs-SWCNT@(polytyramine film) surface constructs, deposited on gold electrodes by potentiodynamic electropolymerization. These constructs constituted recognition units of the chemosensors. The molecular dynamics (MD) designing of DUL-nanoMIPs helped select the most appropriate functional and cross-linking monomers and determine the selectivity of the chemosensor. Three different DUL-nanoMIPs and non-imprinted polymer (nanoNIPs) were prepared with these monomers. DUL-nanoMIPs, synthesized from respective methacrylic acid and ethylene glycol dimethyl acrylate as the functional and cross-linking monomers, revealed the highest affinity to the DUL analyte. The linear dynamic concentration range, extending from 10 pM to 676 nM DUL, and the limit of detection (LOD), equaling 1.6 pM, in the plasma were determined by the DPV chemosensor, outperforming the EIS chemosensor. HPLC-UV measurements confirmed the results of DUL electrochemical chemosensing.

Customizable molecular recognition: advancements in design, synthesis, and application of molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) are unlocking the door to synthetic materials that are capable of molecular recognition.

Magnetic Molecularly Imprinted Polymers: Synthesis and Applications in the Selective Extraction of Antibiotics

Recently, magnetic molecularly imprinted polymers (MMIPs) have integrated molecular imprinting technology (MIT) and magnetic separation technology and become a novel material with specific recognition and effective separation of target molecules. Based on their special function, they can be widely used to detect contaminants such as antibiotics. The antibiotic residues in the environment not only cause harm to the balance of the ecosystem but also induce bacterial resistance to specific antibiotics. Given the above consideration, it is especially important to develop sensitive and selective methods for measuring antibiotics in the complex matrix. The combination of MMIPs and conventional analytical methods provides a rapid approach to separate and determine antibiotics residues. This article gives a systematic overview of synthetic approaches of the novel MMIPs materials, briefly introduces their use in sample pretreatment prior to antibiotic detection, and provides a perspective for future research.

Molecularly Imprinted Materials for Selective Biological Recognition

Molecular imprinting is an approach of generating imprinting cavities in polymer structures that are compatible with the target molecules. The cavities have memory for shape and chemical recognition, similar to the recognition mechanism of antigen-antibody in organisms. Their structures are also called biomimetic receptors or synthetic receptors. Owing to the excellent selectivity and unique structural predictability of molecularly imprinted materials (MIMs), practical MIMs have become a rapidly evolving research area providing key factors for understanding separation, recognition, and regenerative properties toward biological small molecules to biomacromolecules, even cell and microorganism. In this review, the characteristics, morphologies, and applicability of currently popular carrier materials for molecular imprinting, especially the fundamental role of hydrogels, porous materials, hierarchical nanoparticles, and 2D materials in the separation and recognition of biological templates are discussed. Moreover, through a series of case studies, emphasis is given on introducing imprinting strategies for biological templates with different molecular scales. In particular, the differences and connections between small molecular imprinting (bulk imprinting, "dummy" template imprinting, etc.), large molecular imprinting (surface imprinting, interfacial imprinting, etc.), and cell imprinting strategies are demonstrated in detail. Finally, future research directions are provided.

On-Chip Preparation of Streptokinase Entrapped in Chitosan Nanoparticles Used in Thrombolytic Therapy Potentially

The objective of this work was to prepare the streptokinase (SK) entrapped in chitosan nanoparticles (CS NPs) using bulk mixing (BM) and microfluidic (MF) techniques. The physicochemical properties of the samples were characterized by means of scanning electron microscopy and dynamic light scattering analysis for optimizing CS and SK solution concentrations as well as pH values. The obtained results showed that CS NPs fabricated using MF chip have the most uniform morphology, spherical shape, and average diameter of 67 ± 13 nm along with a narrow polydispersity. Conversely, the NP samples prepared via BM method have an irregular and disordered morphology as well as a broad distribution in their particle size (452 ± 300 nm). The in vitro drug release from microfluidically generated CS NPs depicted the controlled release of SK without plateau regime compared to those samples prepared using BM method during 48 h. Also, the drug release kinetic followed Higuchi model which revealed that the Fickian diffusion was the predominant mechanism. Subsequently, in in vivo animal model test, the performance of SK in blood plasma exhibited higher amidolytic activity for SK entrapped in CS NP samples fabricated via MF technique compared to those NPs prepared using BM and also SK alone.