Biocompatibility of nanofilm-encapsulated silicone and silicone-hydrogel contact lenses

Low-Cost Photoelectric Flow Rate Sensors Based on a Flexible Planar Curved Beam Structure for Clinical Treatments

In clinical treatments, reliable flow rate measurements ensure accurate drug delivery during infusions, precise gas delivery during artificial ventilations, etc., thereby reducing patient morbidity and mortality. However, precise flow rate sensors are costly, so medical devices with limited budgets choose cheaper but unsatisfactory flow rate measurement approaches, leading to increased medical risks. Here, a photoelectric flow rate sensor based on a flexible planar curved beam structure (FPCBS) is proposed. The FPCBS ensures low out-of-plane stiffness of the sensitive sheet and allows large deformation in the elastic range, enabling the flow rate sensor to measure the flow rate with high sensitivity over a wide range. Meanwhile, the flow rate sensor can be mass-produced using mature materials and manufacturing technology at less than $5 each. The flow rate sensors are integrated into a commercial infusion pump to measure drug infusion and a home ventilator to monitor respiration. The results are comparable to those measured by a commercial flow rate sensor, demonstrating the applicability of the sensor. Considering its proven outstanding performance at low cost, the flow rate sensor shows great potential in clinical treatment, medical diagnosis, and other medical fields.

Advanced morphological analysis of siloxane-hydrogel contact lenses

The purpose of this work is to provide a better understanding of three-dimensional (3-D) surface texture of siloxane-hydrogel contact lenses (CLs) using atomic force microscopy (AFM) and stereometric analysis. The 3-D surface texture characterization of unworn/worn siloxane-hydrogel CLs made of Filcon V (I FDA group) was performed with stereometric analysis. The atomic force microscopy (AFM) measurements of surface roughness and micromorphology of CLs were made using a Nanoscope V MultiMode (Bruker) in intermittent-contact mode, in air, on square areas of 5 × 5 μm. Stereometric study of 3-D surface texture was made according with ISO 25178-2:2012 for CL_rins (taken from the blister and rinsed with deionized water); CL_ss (preserved for 12 hr in saline solution and rinsed with deionized water); CL_worn-smooth (worn for 8 hr and presenting the smooth type morphology), and CL_worn-sharp (worn for 8 hr and presenting the sharp-type morphology). The 3-D surface texture of siloxane-hydrogel CLs was found to have specific morphological characteristics. Statistical parameters revealed local geometrical and morphological spatial structures at nanometer scale attributed to the specific interactions at the CLs surface. Before wear, the surface micromorphology of Filcon V CLs is regular with uniformly distributed microasperities and relatively small heights (Sq = 0.6 nm). After 12 hr in saline, it is found that the micromorphology changes relatively easily, but retaining the main morphological characteristics (Sq = 1.2 nm). After 8 hr of wear, there are two typical micromorphologies: smooth type, characterized by gutter structures and isolated microasperities (Sq = 2.5 nm), while the sharp type has an appearance with compactly arranged microasperities of hill type flanked by compactly arranged microregions of valley type (Sq = 2.2 nm). Surface statistical parameters allow manufacturers in developing the next generation of CLs with improved surface texture while improving biocompatibility and minimizing the impact of the material on corneal physiology. Furthermore, the micro-elastohydrodynamic lubrication due to surface texture at a nanometer scale between the back surface of the CL with the corneal surface and the front surface of the CL with the under-surface of the eyelid can be deeper and more nuanced to understand in light of modern tribological theories.

Functional cellulose-based hydrogels as extracellular matrices for tissue engineering

Cellulose-based hydrogels are immensely important for tissue engineering. In this review, we attempt to document the source, nature, and application of cellulose-based hydrogels as an extracellular matrix for tissue growth and regeneration. Hydrogels can be prepared either from native cellulose, including both bacterial and plant sources or from cellulose derivatives, such as methyl cellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose or even metal ions such as silver. Cellulose-polymer composite (polymers that include natural sources including chitosan, starch, alginates, collagen, hyaluronic acid, and chitin) are an attractive, inexpensive, and advantageous structural material that is easy to use. Cellulose-based scaffolding materials are widely used in the regeneration of various tissues, such as bone, cartilage, heart, blood vessel, nerve, and liver, among others. In this review, we discuss the most important applications of cellulosic hydrogels in tissue engineering based on their structural compositions.

Advanced drug delivery and targeting technologies for the ocular diseases

INTRODUCTION

Ocular targeted therapy has enormously been advanced by implementation of new methods of drug delivery and targeting using implantable drug delivery systems (DDSs) or devices (DDDs), stimuli-responsive advanced biomaterials, multimodal nanomedicines, cell therapy modalities and medical bioMEMs. These technologies tackle several ocular diseases such as inflammation-based diseases (e.g., scleritis, keratitis, uveitis, iritis, conjunctivitis, chorioretinitis, choroiditis, retinitis, retinochoroiditis), ocular hypertension and neuropathy, age-related macular degeneration and mucopolysaccharidosis (MPS) due to accumulation of glycosaminoglycans (GAGs). Such therapies appear to provide ultimate treatments, even though much more effective, yet biocompatible, noninvasive therapies are needed to control some disabling ocular diseases/disorders.

METHODS

In the current study, we have reviewed and discussed recent advancements on ocular targeted therapies.

RESULTS

On the ground that the pharmacokinetic and pharmacodynamic analyses of ophthalmic drugs need special techniques, most of ocular DDSs/devices developments have been designed to localized therapy within the eye. Application of advanced DDSs such as Subconjunctival insert/implants (e.g., latanoprost implant, Gamunex-C), episcleral implant (e.g., LX201), cationic emulsions (e.g., Cationorm™, Vekacia™, Cyclokat™), intac/punctal plug DDSs (latanoprost punctal plug delivery system, L-PPDS), and intravitreal implants (I-vitaion™, NT-501, NT- 503, MicroPump, Thethadur, IB-20089 Verisome™, Cortiject, DE-102, Retisert™, Iluvein™ and Ozurdex™) have significantly improved the treatment of ocular diseases. However, most of these DDSs/devices are applied invasively and even need surgical procedures. Of these, use of de novo technologies such as advanced stimuli-responsive nanomaterials, multimodal nanosystems (NSs)/nanoconjugates (NCs), biomacromolecualr scaffolds, and bioengineered cell therapies need to be further advanced to get better compliance and higher clinical impacts.

CONCLUSION

Despite mankind successful battle on ocular diseases, our challenge will continue to battle the ocular disease that happen with aging. Yet, we need to understand the molecular aspects of eye diseases in a holistic way and develop ultimate treatment protocols preferably as non-invasive systems.

Hydrogels for ocular drug delivery and tissue engineering

Hydrogels, as crosslinked polymeric three dimensional networks, possess unique structure and behavior in response to the internal and/or external stimuli. As a result, they offer great prospective applications in drug delivery, cell therapy and human tissue engineering. Here, we highlight the potential of hydrogels in prolonged intraocular drug delivery and ocular surface therapy using stem cells incorporated hydrogels.

Kinetics ofIn VitroLysozyme Deposition on Silicone Hydrogel, PMMA, and FDA Groups I, II, and IV Contact Lens Materials

We sought to compare the kinetics of in vitro lysozyme deposition on silicone hydrogel (SH), polymethyl methacrylate (PMMA), and FDA groups I, II, and IV contact lenses. Lenses were incubated in 125I-labeled lysozyme for time periods ranging from 1 hr to 28 days, and radioactive counts were determined. SH lenses and PMMA deposited less lysozyme than conventional hydrogel lenses (p < 0.05). Lysozyme accumulation on group IV lenses reached a maximum on the seventh day and then plateaued, whereas on groups I, II, and SH lenses, deposition continued to increase across all time periods, reiterating that kinetics of lysozyme deposition is highly material dependent.

Effects of poly(2-hydroxyethyl methacrylate) and poly(vinyl-pyrrolidone) hydrogel implants on myopic and normal chick sclera

There has been generally little attention paid to the utilization of biomaterials as an anti-myopia treatment. The purpose of this study was to investigate whether polymeric hydrogels, either implanted or injected adjacent to the outer scleral surface, slow ocular elongation. White Leghorn (Gallus gallus domesticus) chicks were used at 2 weeks of age. Chicks had either (1) a strip of poly(2-hydroxyethyl methacrylate) (pHEMA) implanted monocularly against the outer sclera at the posterior pole, or (2) an in situ polymerizing gel [main ingredient: poly(vinyl-pyrrolidone) (PVP)] injected monocularly at the same location. Some of the eyes injected with the polymer were fitted with a diffuser or a -10D lens. In each experiment, ocular lengths were measured at regular intervals by high frequency A-scan ultrasonography, and chicks were sacrificed for histology at staged intervals. No in vivo signs of either orbital or ocular inflammation were observed. The pHEMA implant significantly increased scleral thickness by the third week, and the implant became encapsulated with fibrous tissue. The PVP-injected eyes left otherwise untreated, showed a significant increase in scleral thickness, due to increased chondrocyte proliferation and extracellular matrix deposition. However, there was no effect of the PVP injection on ocular elongation. In eyes wearing optical devices, there was no effect on either scleral thickness or ocular elongation. These results represent "proof of principle" that scleral growth can be manipulated without adverse inflammatory responses. However, since neither approach slowed ocular elongation, additional factors must influence scleral surface area expansion in the avian eye.

Hydrogels for tissue engineering and delivery of tissue-inducing substances

This manuscript presents hydrogels (HGs) from a tissue engineering perspective being especially written for those who are approaching this field by offering a concise but inclusive review of hydrogel synthesis, properties, characterization methods, and applications.