Local Delivery and Sustained-Release of Nitric Oxide Donor Loaded in Mesoporous Silica Particles for Efficient Treatment of Primary Open-Angle Glaucoma

The menace of severe adverse events and deaths associated with viral gene therapy and its potential solution

Over the past decade, in vivo gene replacement therapy has significantly advanced, resulting in market approval of numerous therapeutics predominantly relying on adeno-associated viral vectors (AAV). While viral vectors have undeniably addressed several critical healthcare challenges, their clinical application has unveiled a range of limitations and safety concerns. This review highlights the emerging challenges in the field of gene therapy. At first, we discuss both the role of biological barriers in viral gene therapy with a focus on AAVs, and review current landscape of in vivo human gene therapy. We delineate advantages and disadvantages of AAVs as gene delivery vehicles, mostly from the safety perspective (hepatotoxicity, cardiotoxicity, neurotoxicity, inflammatory responses etc.), and outline the mechanisms of adverse events in response to AAV. Contribution of every aspect of AAV vectors (genomic structure, capsid proteins) and host responses to injected AAV is considered and substantiated by basic, translational and clinical studies. The updated evaluation of recent AAV clinical trials and current medical experience clearly shows the risks of AAVs that sometimes overshadow the hopes for curing a hereditary disease. At last, a set of established and new molecular and nanotechnology tools and approaches are provided as potential solutions for mitigating or eliminating side effects. The increasing number of severe adverse reactions and, sadly deaths, demands decisive actions to resolve the issue of immune responses and extremely high doses of viral vectors used for gene therapy. In response to these challenges, various strategies are under development, including approaches aimed at augmenting characteristics of viral vectors and others focused on creating secure and efficacious non-viral vectors. This comprehensive review offers an overarching perspective on the present state of gene therapy utilizing both viral and non-viral vectors.

Evaluation of the Ocular Safety of Hollow Mesoporous Organosilica Nanoparticles with Different Tetrasulfur Bond Content

Background

Drug therapy for eye diseases has been limited by multiple protective mechanisms of the eye, which can be improved using well-designed drug delivery systems. Mesoporous silica nanoparticles (MSNs) had been used in many studies as carriers of therapeutic agents for ocular diseases treatment. However, no studies have focused on ocular biosafety. Considering that MSNs containing tetrasulfur bonds have unique advantages and have drawn increasing attention in drug delivery systems, it is necessary to explore the ocular biosafety of tetrasulfur bonds before their widespread application as ophthalmic drug carriers.

Methods

In this study, hollow mesoporous silica nanoparticles (HMSNs) with different tetrasulfur bond contents were prepared and characterized. The ocular biosafety of HMSN-E was evaluated in vitro on the three selected ocular cell lines, including corneal epithelial cells, lens epithelial cells and retinal endothelial cells (HREC), and in vivo by using topical eye drops and intravitreal injections.

Results

In cellular experiments, HMSNs caused obvious S content-dependent cytotoxic effect. HMSNs with the highest tetrasulfur bond content (HMSN-E), showed the highest cytotoxicity among all the HMSNs, and HREC was the most vulnerable cell to HMSN-E. It was shown that HMSN-E could react with intracellular GSH to generate H2S and decrease intracellular GSH concentration. Treatment of HREC with HMSN-E increased intracellular ROS, decreased mitochondrial membrane potential, and induced cell cycle arrest at the G1/S checkpoint, finally caused apoptosis and necrosis of HREC. Topical eye drops of HMSN-E could cause corneal damage. The intravitreal injection of HMSN-E could induce inflammation in the vitreum and ganglion cell layers, resulting in vitreous opacities and retinal abnormalities.

Conclusion

The incorporation of tetrasulfur bonds into HMSN can have toxic effects on ocular tissues. Therefore, when mesoporous silica nanocarriers are designed for ophthalmic pharmaceuticals, the ocular toxicity of the tetrasulfur bonds should be considered.

Hyaluronic Acid-Coated Silica Nanoparticles for Targeted Delivery of Nitric Oxide to Cancer Cells

Drug resistance and off-target toxicity are two of the greatest challenges to chemotherapeutic melanoma treatments. Nitric oxide (NO) represents an attractive alternative to conventional therapeutics due to its numerous anticancer properties and low probability of engendering resistance. As NO is highly reactive, macromolecular NO donors are needed for the controlled and targeted delivery of NO for therapeutic applications. Herein, mesoporous silica nanoparticles (MSNs) coated with hyaluronic acid (HA) were developed as a NO delivery system to facilitate controlled delivery to cancer cells through both passive and active targeting via the enhanced permeation and retention effect and directed binding of HA with CD44 receptors, respectively. The aminosilane modification, HA concentration, and HA molecular weight were systematically evaluated to facilitate the MSN coating and NO loading. The hydrodynamic diameter and dispersity of the nanoparticles increased after HA coating due to the hydrophilic nature of HA, with greater increases observed at higher HA molecular weight. Lower starting concentrations of HA and aminosilanes with longer alkyl chains favored more efficient HA coating. Faster NO-release kinetics and lower NO payloads were observed for the HA-coated MSNs relative to uncoated MSNs. However, the localized delivery of NO to cancer cells through the active targeting conferred by HA increased levels of oxidative stress and induced mitochondria-mediated apoptosis in melanoma cells. Cytotoxicity was also evaluated against human dermal fibroblasts, with the use of 6 kDa HA-coated MSNs resulting in the greatest therapeutic indices. Enhanced internalization of HA-coated nanoparticles into melanoma cells versus uncoated nanoparticles was visualized with confocal microscopy and quantified by fluorescence spectroscopy. In total, HA-coated MSNs represent a promising NO delivery system for potential use as a chemotherapeutic for skin melanomas.

Breaking Barriers: Nanomedicine-Based Drug Delivery for Cataract Treatment

Cataract is a leading cause of blindness globally, and its surgical treatment poses a significant burden on global healthcare. Pharmacologic therapies, including antioxidants and protein aggregation reversal agents, have attracted great attention in the treatment of cataracts in recent years. Due to the anatomical and physiological barriers of the eye, the effectiveness of traditional eye drops for delivering drugs topically to the lens is hindered. The advancements in nanomedicine present novel and promising strategies for addressing challenges in drug delivery to the lens, including the development of nanoparticle formulations that can improve drug penetration into the anterior segment and enable sustained release of medications. This review introduces various cutting-edge drug delivery systems for cataract treatment, highlighting their physicochemical properties and surface engineering for optimal design, thus providing impetus for further innovative research and potential clinical applications of anti-cataract drugs.

Novel Biomaterials in Glaucoma Treatment

Glaucoma is a significant cause of blindness worldwide, and its treatment remains challenging. The disease progressively leads to damage to the optic disc and thus loss of visual acuity and visual field. High intraocular pressure (IOP) is a common risk factor. There are three major methods to treat this disease: topical, laser, and surgical. None of these are completely satisfactory; therefore, alternatives using new biomaterials are being sought. Since biomaterial engineering has experienced significant growth in recent decades, its products are gradually being introduced to various branches of medicine, with the exception of ophthalmology. Biomaterials, such as glaucoma drainage implants, have been successfully used to treat glaucoma. There is significant ongoing research on biomaterials as drug delivery systems that could overcome the disadvantages of topical glaucoma treatment, such as poor intraocular penetration or frequent drug administration. This article summarizes the use of novel biomaterials for glaucoma treatment presented in the literature. The literature search was based on articles published in English on PubMed.gov, Cochranelibrary.com, and Scopus.com between 2018 and 2023 using the following term "biomaterials in glaucoma." A total of 103 published articles, including twenty-two reviews, were included. Fifty-nine articles were excluded on the basis of their titles and abstracts.

Controllable release of nitric oxide from an injectable alginate hydrogel

Currently, the controlled release of nitric oxide (NO) plays a crucial role in various biomedical applications. However, injectable NO-releasing materials remain an underexplored research field to date. In this study, via the incorporation of S-nitroso-N-acetyl-penicillamine (SNAP) as an NO donor, a family of NO-releasing injectable hydrogels was synthesized through the in situ cross-linking between sodium alginate and calcium ion induced by D-(+)-gluconate δ-lactone as an initiator. Initially, the organic functional groups and the corresponding morphologies of the resulting injectable hydrogels were characterized by IR and SEM spectroscopies, respectively. The NO release times of hydrogels with different SNAP loading amounts could reach up to 36-47 h. Due to the release of NO, the highest antibacterial rates of these injectable hydrogels against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were up to 95 %, respectively. Furthermore, the matrix of these hydrogels demonstrated great water absorption ability, swelling behavior, and degradation performance. Finally, we expect that these NO-releasing injectable hydrogels could have great potential applications various biomedical material fields.

Peroxynitrite-Scavenging Organosilica Nanomedicines for Light-Controllable NO Release and Precision On-Demand Glaucoma Therapy

Nitric oxide (NO) is a promising approach for treating ocular hypertension and glaucoma. However, its clinical application is limited by its uncontrollable release and the unwanted overproduction of peroxynitrite. Herein, a denitrifying hollow mesoporous organosilica nanoparticle (HMMN) with framework cohybridization is first constructed to encapsulate S-nitroso-N-acetyl-d,l-penicillamine (SNAP) to produce SNAP@HMMN with dual capacities of selective peroxynitrite removal and controllable NO release. Featuring a large corneal permeability, the well-designed SNAP@HMMN can achieve trans-corneal delivery to reach the target trabecular meshwork (TM)/Schlemm's canal (SC) site. Upon light irradiation, the intraocular pressure (IOP) is appropriately lowered in an adjustable and long-lasting manner while the outflow tissues are protected from nitrative damage, which is expected to realize precision on-demand glaucoma therapy with little biosafety concern, promising significant clinical translational potential.

Polarity-Sensitive Probe for Two-Photon Fluorescence Lifetime Imaging of Lipid Droplets In Vitro and In Vivo

Lipid droplets (LDs) are crucial organelles used to store lipids and participate in lipid metabolism in cells. The abnormal aggregation and polarity change of LDs are associated with the occurrence of diseases, such as steatosis. Herein, the polarity-sensitive probe TBPCPP with a donor-acceptor-π-acceptor (D-A-π-A) structure was designed and synthesized. The TBPCPP has a large Stokes shift (∼220 nm), excellent photostability, high LD targeting, and considerable two-photon absorption (TPA) cross-section (∼226 GM), enabling deep two-photon imaging (∼360 μm). In addition, the fluorescence lifetime of TBPCPP decreases linearly with increasing solvent polarity. Therefore, with the assistance of two-photon fluorescence lifetime imaging microscopy (TP-FLIM), TBPCPP has successfully achieved not only the visualization of polarity changes caused by LD accumulation in HepG-2 cells but also lipid-specific imaging and visualization of different polarities in lipid-rich regions in zebrafish for the first time. Furthermore, TP-FLIM revealed that the polarity gradually decreases during steatosis in HepG-2 cells, which provided new insights into the diagnosis of steatosis.

Poly(l-Histidine)-Mediated On-Demand Therapeutic Delivery of Roughened Ceria Nanocages for Treatment of Chemical Eye Injury

Development of topical bioactive formulations capable of overcoming the low bioavailability of conventional eye drops is critically important for efficient management of ocular chemical burns. Herein, a nanomedicine strategy is presented to harness the surface roughness-controlled ceria nanocages (SRCNs) and poly(l-histidine) surface coatings for triggering multiple bioactive roles of intrinsically therapeutic nanocarriers and promoting transport across corneal epithelial barriers as well as achieving on-demand release of dual drugs [acetylcholine chloride (ACh) and SB431542] at the lesion site. Specifically, the high surface roughness helps improve cellular uptake and therapeutic activity of SRCNs while exerting a negligible impact on good ocular biocompatibility of the nanomaterials. Moreover, the high poly(l-histidine) coating amount can endow the SRCNs with an ≈24-fold enhancement in corneal penetration and an effective smart release of ACh and SB431542 in response to endogenous pH changes caused by tissue injury/inflammation. In a rat model of alkali burn, topical single-dose nanoformulation can efficaciously reduce corneal wound areas (19-fold improvement as compared to a marketed eye drops), attenuate ≈93% abnormal blood vessels, and restore corneal transparency to almost normal at 4 days post-administration, suggesting great promise for designing multifunctional metallic nanotherapeutics for ocular pharmacology and tissue regenerative medicine.

Bacteria-Targeted Combined with Photothermal/NO Nanoparticles for the Treatment and Diagnosis of MRSA Infection In Vivo

Currently, undeveloped diagnosis and delayed treatment of bacteria-infected sites in vivo not only expand the risk of tissue infection but are also a major clinical cause of multiple drug-resistant bacterial infections. Herein, an efficient nanoplatform for near-infrared (NIR)-light-controlled release and bacteria-targeted delivery of nitric oxide (NO) combined with photothermal therapy (PTT) is presented. Using maltotriose-decorated mesoporous polydopamine (MPDA-Mal) and BNN6, a smart antibacterial (B@MPDA-Mal) is developed to combine bacterial targeting, gas-controlled release, and PTT. Utilizing bacteria's unique maltodextrin transport system, B@MPDA-Mal can accurately distinguish bacterial infection from sterile inflammation and target the bacteria-infected sites for efficient drug enrichment. Moreover, NIR-light causes MPDA to generate heat, which not only effectively induces BNN6 to produce NO, but also raises the temperature to harm the bacteria further. NO/photothermal combination therapy effectively eliminates biofilm and drug-resistant bacteria. The myositis model of methicillin-resistant Staphylococcus aureus infection is established and indicates that B@MPDA-Mal can successfully eradicate inflammation and abscesses in mice. Meanwhile, magnetic resonance imaging technology is used to monitor the treatment procedure and healing outcomes. Given the aforementioned advantages, the smart antibacterial nanoplatform B@MPDA-Mal can be used as a potential therapeutic tool in the biomedical field against drug-resistant bacterial infections.

Combined Therapy of Experimental Autoimmune Uveitis by a Dual-Drug Nanocomposite Formulation with Berberine and Dexamethasone

Purpose

Autoimmune uveitis is a kind of sight-threatening ocular and systemic disorders. Recent treatments on autoimmune uveitis still remain many limitations due to extreme complexity and undetermined pathogenesis. In this study, a novel dual-drug nanocomposite formulation is developed to treat experimental autoimmune uveitis by a combined and sustained therapy method.

Methods

The dual-drug nanocomposite formulation is constructed by integrating berberine (BBR)-loaded mesoporous silica nanoparticles (MSNs) into dexamethasone (DEX)-loaded thermogel (BBR@MSN-DEX@Gel). The BBR@MSN-DEX@Gel is characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometer and rheometer. The in vitro drug release profile, cytotoxicity and anti-inflammation effectiveness of BBR@MSN-DEX@Gel on lipopolysaccharide-stimulated human conjunctival epithelial cells are investigated. After the in vivo drug release profile and biosafety of the dual-drug nanocomposite formulation are confirmed, its treatment effectiveness is fully assessed based on the induced experimental autoimmune uveitis (EAU) Lewis rat's model.

Results

The dual-drug nanocomposite formulation has good injectability and thermosensitivity, suitable for administration by an intravitreal injection. The BBR@MSN-DEX@Gel has been found to sustainably release both drugs for up to 4 weeks. The carrier materials have minimal in vitro cytotoxicity and high in vivo biosafety. BBR@MSN-DEX@Gel presents obviously anti-inflammatory effectiveness in vitro. After administration of BBR@MSN-DEX@Gel into Lewis rat's eye with EAU by an intravitreal injection, the nanocomposite formulation significantly suppresses inflammatory reaction of autoimmune uveitis via a dual-drug combined and sustained therapy method, compared with the equivalent dose of single-component formulations.

Conclusion

BBR@MSN-DEX@Gel serves as a promising dual-drug nanocomposite formulation for future treatment of autoimmune uveitis.

Trans-corneal drug delivery strategies in the treatment of ocular diseases

The cornea is a remarkable tissue that possesses specialized structures designed to safeguard the eye against foreign objects. However, its unique properties also make it challenging to deliver drugs in a non-invasive manner. This review highlights recent advancements in achieving highly efficient drug transport across the cornea, focusing on nanomaterials. We have classified these strategies into three main categories based on their mechanisms and have analyzed their success and limitations in a systematic manner. The purpose of this review is to examine potential general principles that could improve drug penetration through the cornea and other natural barriers in the eye. We hope it will inspire the development of more effective drug delivery systems that can better treat ocular diseases.

Breaking Barriers in Eye Treatment: Polymeric Nano-Based Drug-Delivery System for Anterior Segment Diseases and Glaucoma

The eye has anatomical structures that function as robust static and dynamic barriers, limiting the penetration, residence time, and bioavailability of medications administered topically. The development of polymeric nano-based drug-delivery systems (DDS) could be the solution to these challenges: it can pass through ocular barriers, offering higher bioavailability of administered drugs to targeted tissues that are otherwise inaccessible; it can stay in ocular tissues for longer periods of time, requiring fewer drug administrations; and it can be made up of polymers that are biodegradable and nano-sized, minimizing the undesirable effects of the administered molecules. Therefore, therapeutic innovations in polymeric nano-based DDS have been widely explored for ophthalmic drug-delivery applications. In this review, we will give a comprehensive overview of polymeric nano-based drug-delivery systems (DDS) used in the treatment of ocular diseases. We will then examine the current therapeutic challenges of various ocular diseases and analyze how different types of biopolymers can potentially enhance our therapeutic options. A literature review of the preclinical and clinical studies published between 2017 and 2022 was conducted. Thanks to the advances in polymer science, the ocular DDS has rapidly evolved, showing great promise to help clinicians better manage patients.

Dendrimer and dendrimer gel-derived drug delivery systems: Breaking bottlenecks of topical administration of glaucoma medications

Due to high structural flexibility, multidrug carrying capability, and tunable size, dendrimers have been used as suitable carriers for ophthalmic drug delivery. Drug molecules can be either encapsulated or chemically coupled to dendrimers. The nanoscopic size, spheroidal shape, and cationic surface of polyamidoamine (PAMAM) dendrimers promote their interaction with the cornea and result in prolonged precorneal retention. Dendrimers could be further cross-linked to produce three-dimensional hydrogel networks or dendrimer hydrogels (DH). The properties of the DH can be readily adjusted to maintain both fluidity and adhesiveness, making them suitable for developing topical ocular drug formulations. Micro-/nano-sized DHs, that is, dendrimer micro-/nano-gels, have unique properties such as ease of administration, large specific surface area for adhesion, and drug targeting functionalities, making them attractive for ophthalmic drug delivery. This perspective reports advances in PAMAM dendrimer based drug delivery systems including drug conjugates and micro- and nano-gels to enhance and sustain the delivery of multiple anti-glaucoma drugs, Dendrimer and dendrimer gel-derived drug delivery systems hold great potential as multifunctional topical drug delivery systems for the eye.

Combined Anti-Angiogenic and Anti-Inflammatory Nanoformulation for Effective Treatment of Ocular Vascular Diseases

Background

Ocular vascular diseases are the major causes of visual impairment, which are characterized by retinal vascular dysfunction and robust inflammatory responses. Traditional anti-angiogenic or anti-inflammatory drugs still have limitations due to the short-acting effects. To improve the anti-angiogenic or anti-inflammatory efficiency, a dual-drug nanocomposite formulation was proposed for combined anti-angiogenic and anti-inflammatory treatment of ocular vascular diseases.

Methods 

CBC-MCC@hMSN(SM) complex nanoformulation was prepared by integrating conbercept (CBC, an anti-angiogenic drug) and MCC950 (MCC, an inhibitor of inflammation) into the surface-modified hollow mesoporous silica nanoparticles (hMSN(SM)). CBC-MCC@hMSN(SM) complex nanoformulation was then characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, zeta potentials, and nitrogen adsorption-desorption measurement. CBC and MCC release profile, cytotoxicity, tissue toxicity, anti-angiogenic effects, and anti-inflammatory effects of CBC-MCC@hMSN(SM) were estimated using the in vitro and in vivo experiments.

Results

 CBC-MCC@hMSN(SM) complex had no obvious cytotoxicity and tissue toxicity and did not cause a detectable ocular inflammatory responses. CBC-MCC@hMSN(SM) complex was more effective than free CBC or MCC in suppressing endothelial angiogenic effects and inflammatory responses in vitro. A single intraocular injection of CBC-MCC@hMSN(SM) complex potently suppressed diabetes-induced retinal vascular dysfunction, choroidal neovascularization, and inflammatory responses for up to 6 months.

Conclusion 

Combined CBC and MCC nanoformulation provides a promising strategy for sustained suppression of pathological angiogenesis and inflammatory responses to improve the treatment outcomes of ocular vascular diseases.

Nitroprusside─Expanding the Potential Use of an Old Drug Using Nanoparticles

For more than 70 years, sodium nitroprusside (SNP) has been used to treat severe hypertension in hospital emergency settings. During this time, a few other clinical uses have also emerged such as in the treatment of acute heart failure as well as improving mitral incompetence and in the intra- and perioperative management during heart surgery. This drug functions by releasing nitric oxide (NO), which modulates several biological processes with many potential therapeutic applications. However, this small molecule has a short lifetime, and it has been administered through the use of NO donor molecules such as SNP. On the other hand, SNP also has some setbacks such as the release of cyanide ions, high water solubility, and very fast NO release kinetics. Currently, there are many drug delivery strategies that can be applied to overcome many of these limitations, providing novel opportunities for the use of old drugs, including SNP. This Perspective describes some nitroprusside properties and highlights new potential therapeutic uses arising from the use of drug delivery systems, mainly silica-based nanoparticles. There is a series of great opportunities to further explore SNP in many medical issues as reviewed, which deserves a closer look by the scientific community.

Identifying and categorizing compounds that reduce corneal transforming growth factor beta induced protein levels: a scoping review

INTRODUCTION

Transforming growth factor beta induced (TGFBI) gene mutations have been reported as the cause of a group of genetically inherited, visually debilitating, corneal dystrophies (CD). A scoping literature review to identify and categorize compounds that inhibit corneal TGFBI expression and/or promote TGFBIp degradation was performed. Emphasis was given to their potential to be used as a cost-effective approach via drug repurposing.

AREAS COVERED

We performed a thorough search of original peer-reviewed literature using electronic bibliographic databases and selected articles according to a set of criteria. The total number of articles retrieved from the search terms applied to the databases was 2344. The number of relevant full-text articles included added up to 19. We identified 16 compounds that can theoretically reduce the levels of mutant TGFBIp in human corneal cells.

EXPERT OPINION

Currently, the only temporary treatments available for this condition are lubricant drops and surgery. Here, we explored the crosstalk between cascades that regulate TGFBI expression and identified compounds that target these pathways. Compounds that inhibit DNA synthesis and function, increase elimination of TGFBIp or bind to mutant TGFBIp were also explored with the aim of highlighting promising compounds that can be used in future cost-effective drug-repurposing studies.

An Update on Novel Ocular Nanosystems with Possible Benefits in the Treatment of Corneal Neovascularization

Corneal neovascularization (CNV) is an ocular pathological change that results from an imbalance between angiogenic factors and antiangiogenic factors as a result of various ocular insults, including infection, inflammation, hypoxia, trauma, corneal degeneration, and corneal transplantation. Current clinical strategies for the treatment of CNV include pharmacological treatment and surgical intervention. Despite some degree of success, the current treatment strategies are restricted by limited efficacy, adverse effects, and a short duration of action. Recently, gene-based antiangiogenic therapy has become an emerging strategy that has attracted considerable interest. However, potential complications with the use of viral vectors, such as potential genotoxicity resulting from long-term expression and nonspecific targeting, cannot be ignored. The use of ocular nanosystems (ONS) based on nanotechnology has emerged as a great advantage in ocular disease treatment during the last two decades. The potential functions of ONS range from nanocarriers, which deliver drugs and genes to target sites in the eye, to therapeutic agents themselves. Various preclinical studies conducted to date have demonstrated promising results of the use of ONS in the treatment of CNV. In this review, we provide an overview of CNV and its current therapeutic strategies and summarize the properties and applications of various ONS related to the treatment of CNV reported to date. Our goal is to provide a comprehensive review of these considerable advances in ONS in the field of CNV therapy over the past two decades to fill the gaps in previous related reports. Finally, we discuss existing challenges and future perspectives of the use of ONS in CNV therapy, with the goal of providing a theoretical contribution to facilitate future practical growth in the area.

Erianin-Loaded Photo-Responsive Dendrimer Mesoporous Silica Nanoparticles: Exploration of a Psoriasis Treatment Method

Psoriasis is a chronic inflammatory skin disorder accompanied by excessive keratinocyte proliferation. Erianin (Eri) is an ideal drug candidate for inhibiting proliferation and inducing apoptosis in the treatment of psoriasis. However, Eri’s poor water solubility and low penetration activity across the skin hinder its application in local medicine. In this study, we developed a novel photo-responsive dendritic mesoporous silica nanoparticle-based carrier to deliver erianin, improved its bioavailability, and achieved sustained-release effects. Spiropyran (SP), 3-aminopropyltriethoxysilane (APTES), and perfluorodecyltriethoxysilane (PFDTES) were conjugated to the outer surface, which allowed Eri to be released in response to UV radiation. The physicochemical properties of photo-responsive dendritic mesoporous silica nanoparticles (Eri-DMSN@FSP) were characterized via multiple techniques, such as using a Fourier-transform infrared spectrometer, a high-resolution transmission electron microscope, and nuclear magnetic resonance (NMR) spectroscopy. The anti-proliferative properties and light-triggered release of erianin-loaded photo-responsive dendritic mesoporous silica nanoparticles were assessed via the MTT assay and a drug release study in vitro. Erianin-loaded photo-responsive dendritic mesoporous silica nanoparticles (UV) exhibit a significantly enhanced HaCat cell-inhibiting efficacy compared to other formulations, as demonstrated by their extremely low cell viability of 10.0% (concentration: 500 mg/mL), indicating their capability to release a drug that responds to UV radiation. The cellular uptake of photo-responsive dendritic mesoporous silica nanoparticles (DMSN@FSP) was observed via confocal laser scanning microscopy (CLSM). These experimental results show that Eri-DMSN@FSP could be effectively endocytosed into cells and respond to ultraviolet light to release Eri, achieving a more effective psoriasis treatment. Therefore, this drug delivery system may be a promising strategy for addressing the question of Eri’s delivery and psoriasis therapy.

Recent achievements in nano-based technologies for ocular disease diagnosis and treatment, review and update

Ocular drug delivery is one of the most challenging endeavors among the various available drug delivery systems. Despite having suitable drugs for the treatment of ophthalmic disease, we have not yet succeeded in achieving a proper drug delivery approach with the least adverse effects. Nanotechnology offers great opportunities to overwhelm the restrictions of common ocular delivery systems, including low therapeutic effects and adverse effects because of invasive surgery or systemic exposure. The present review is dedicated to highlighting and updating the recent achievements of nano-based technologies for ocular disease diagnosis and treatment. While further effort remains, the progress illustrated here might pave the way to new and very useful ocular nanomedicines.

Silica nanoparticles: Biomedical applications and toxicity

Silica nanoparticles (SiNPs) are composed of silicon dioxide, the most abundant compound on Earth, and are used widely in many applications including the food industry, synthetic processes, medical diagnosis, and drug delivery due to their controllable particle size, large surface area, and great biocompatibility. Building on basic synthetic methods, convenient and economical strategies have been developed for the synthesis of SiNPs. Numerous studies have assessed the biomedical applications of SiNPs, including the surface and structural modification of SiNPs to target various cancers and diagnose diseases. However, studies on the in vitro and in vivo toxicity of SiNPs remain in the exploratory stage, and the toxicity mechanisms of SiNPs are poorly understood. This review covers recent studies on the biomedical applications of SiNPs, including their uses in drug delivery systems to diagnose and treat various diseases in the human body. SiNP toxicity is discussed in terms of the different systems of the human body and the individual organs in those systems. This comprehensive review includes both fundamental discoveries and exploratory progress in SiNP research that may lead to practical developments in the future.

Ocular Nanomedicine

Intrinsic shortcomings associated with conventional therapeutic strategies often compromise treatment efficacy in clinical ophthalmology, prompting the rapid development of versatile alternatives for satisfactory diagnostics and therapeutics. Given advances in material science, nanochemistry, and nanobiotechnology, a broad spectrum of functional nanosystems has been explored to satisfy the extensive requirements of ophthalmologic applications. In the present review, the recent progress in nanosystems, both conventional and emerging nanomaterials in ophthalmology from state-of-the-art studies, are comprehensively examined and the role of their fundamental physicochemical properties in bioavailability, tissue penetration, biodistribution, and elimination after interacting with the ophthalmologic microenvironment emphasized. Furthermore, along with the development of surface engineering of nanomaterials, emerging theranostic methodologies are promoted as potential alternatives for multipurpose ocular applications, such as emerging biomimetic ophthalmology (e.g., smart electrochemical eye), thus provoking a holistic review of "ocular nanomedicine." By affording insight into challenges encountered by ocular nanomedicine and further highlighting the direction of future studies, this review provides an incentive for enriching ocular nanomedicine-based fundamental research and future clinical translation.

Mesoporous Silica-Based Nanoparticles as Non-Viral Gene Delivery Platform for Treating Retinitis Pigmentosa

BACKGROUND

Gene therapy is a therapeutic possibility for retinitis pigmentosa (RP), in which therapeutic transgenes are currently delivered to the retina by adeno-associated viral vectors (AAVs). Although their safety and efficacy have been demonstrated in both clinical and preclinical settings, AAVs present some technical handicaps, such as limited cargo capacity and possible immunogenicity in repetitive doses. The development of alternative, non-viral delivery platforms like nanoparticles is of great interest to extend the application of gene therapy for RP.

METHODS

Amino-functionalized mesoporous silica-based nanoparticles (N-MSiNPs) were synthesized, physico-chemically characterized, and evaluated as gene delivery systems for human cells in vitro and for retinal cells in vivo. Transgene expression was evaluated by WB and immunofluorescence. The safety evaluation of mice subjected to subretinal injection was assessed by ophthalmological tests (electroretinogram, funduscopy, tomography, and optokinetic test).

RESULTS

N-MSiNPs delivered transgenes to human cells in vitro and to retinal cells in vivo. No adverse effects were detected for the integrity of the retinal tissue or the visual function of treated eyes. N-MSiNPs were able to deliver a therapeutic transgene candidate for RP, PRPF31, both in vitro and in vivo.

CONCLUSIONS

N-MSiNPs are safe for retinal delivery and thus a potential alternative to viral vectors.

Mechanistic study of silica nanoparticles on the size-dependent retinal toxicity in vitro and in vivo

Background

Silica nanoparticles (SiO₂ NPs) are extensively applied in the biomedical field. The increasing medical application of SiO₂ NPs has raised concerns about their safety. However, studies on SiO₂ NP-induced retinal toxicity are lacking.

Methods

We investigated the retinal toxicity of SiO₂ NPs with different sizes (15 and 50 nm) in vitro and in vivo along with the underlying mechanisms. The cytotoxicity of SiO₂ NPs with different sizes was assessed in R28 human retinal precursor cells by determining the ATP content and LDH release. The cell morphologies and nanoparticle distributions in the cells were analyzed by phase-contrast microscopy and transmission electron microscopy, respectively. The mitochondrial membrane potential was examined by confocal laser scanning microscopy. The retinal toxicity induced by SiO₂ NPs in vivo was examined by immunohistochemical analysis. To further investigate the mechanism of retinal toxicity induced by SiO₂ NPs, reactive oxygen species (ROS) generation, glial cell activation and inflammation were monitored.

Results

The 15-nm SiO₂ NPs were found to have higher cytotoxicity than the larger NPs. Notably, the 15-nm SiO₂ NPs induced retinal toxicity in vivo, as demonstrated by increased cell death in the retina, TUNEL-stained retinal cells, retinal ganglion cell degeneration, glial cell activation, and inflammation. In addition, The SiO₂ NPs caused oxidative stress, as demonstrated by the increase in the ROS indicator H₂DCF-DA. Furthermore, the pretreatment of R28 cells with N-acetylcysteine, an ROS scavenger, attenuated the ROS production and cytotoxicity induced by SiO₂ NPs.

Conclusions

These results provide evidence that SiO₂ NPs induce size-dependent retinal toxicity and suggest that glial cell activation and ROS generation contribute to this toxicity.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01326-8.

Nano-in-Nano Dendrimer Gel Particles for Efficient Topical Delivery of Antiglaucoma Drugs into the Eye

Low bioavailability of topically applied drugs remains a significant challenge for long-term glaucoma therapy. To enhance drug delivery efficiency, we developed dendrimer gel particles that collectively exhibit structural benefits of dendrimer, hydrogel, and particles, using the inverse emulsion method coupled with the highly efficient aza-Michael addition reaction (IEaMA). This hierarchical approach would maximize the utility of the structural features of existing ocular drug delivery systems. We have tested the delivery efficiency and efficacy of two first-line antiglaucoma drugs, brimonidine tartrate (BT) and timolol maleate (TM), which were loaded into dendrimer gel particles of various sizes, i.e., nDHP (nano-in-nano dendrimer hydrogel particles, ~200 nm), μDHP3 (3 μm), and μDHP10 (9 μm). We found that nDHP was superior to μDHP3 and μDHP10 in terms of cytocompatibility, degradability, drug release kinetics, and corneal permeability. The nDHPs increased drug corneal permeability by 17-fold compared to plain drug solution and enabled zero-order prolonged drug release kinetics. The nDHP-based formulation demonstrated pronounced IOP-lowering effects in both single-dose test and 7-day chronic daily dosing test in both Brown Norway rats and glaucoma mice. Taken together, we have developed nano-in-nano dendrimer gel particles for precise dosing and enabling sustained and synergistic efficacy of antiglaucoma drugs, which could be clinically impactful for improving glaucoma treatment.

The Application of Nitric Oxide for Ocular Hypertension Treatment

Despite of various therapeutic methods for treating ocular hypertension and glaucoma, it still remains the leading cause of irreversible blindness. Intraocular pressure (IOP) lowering is the most effective way to slow disease progression and prevent blindness. Among the ocular hypotensive drugs currently in use, only a couple act on the conventional outflow system, which is the main pathway for aqueous humor outflow and the major lesion site resulting in ocular hypertension. Nitric oxide (NO) is a commendable new class of glaucoma drugs that acts on the conventional outflow pathway. An increasing number of nitric oxide donors have been developed for glaucoma and ocular hypertension treatment. Here, we will review how NO lowers IOP and the types of nitric oxide donors that have been developed. And a brief analysis of the advantages and challenges associated with the application will be made. The literature used in this review is based on Pubmed database search using ‘nitric oxide’ and ‘glaucoma’ as key words.

Endogenous dual stimuli-activated NO generation in the conventional outflow pathway for precision glaucoma therapy

High intraocular pressure (IOP) has been regarded as a predominant risk factor for glaucoma. Nitric oxide (NO) is shown to lower IOP, but the magnitude and duration of IOP reduction are not satisfying due to the poor cornea penetration of NO drugs and limited NO generation in the trabecular meshwork (TM)/Schlemm's canal (SC) area. Herein, we introduce deep cornea penetrating biodegradable hollow mesoporous organosilica (HOS) nanocapsules for the efficient co-delivery of hydrophobic JS-K (J_R) and hydrophilic l-Arginine (L_O). The resulting HOS-J_RL_O can be reduced and oxidized by the ascorbic acid (AA) and catalysis of endothelial nitric oxide synthase (eNOS) in the TM/SC microenvironment to release NO for inducing appreciable IOP reduction in various glaucoma mouse models. In addition to developing an endogenous stimuli-responsive NO nanotherapeutic, this study is also expected to establish a versatile, non-invasive, and efficacious treatment paradigm for precision glaucoma therapy.

Inhibiting corneal neovascularization by sustainably releasing anti-VEGF and anti-inflammation drugs from silica-thermogel nanohybrids

Corneal neovascularization (CNV) is one of the main factors that induce blindness worldwide. To effectively inhibit CNV, a novel nanohybrid has been developed by incorporating anti-VEGF bevacizumab (BEV)-loaded mesoporous silica nanoparticles (BEV@MSN) into the thermogel matrix with anti-inflammation cyclosporine A (CsA) (BEV@MSN-CsA@Thermogel). This nanohybrid regulates the in vitro release of both bevacizumab and cyclosporine A in a sustainable way for up to four weeks to enhance CNV inhibition through the synergistic anti-VEGF and anti-inflammation. The carrier materials (i.e. silica and thermogel) in this nanohybrid do not show any cytotoxicity to human Tenon's fibroblasts, corneal epithelial cells and corneal endothelial cells. BEV@MSN-CsA@Thermogel effectively prevents proliferation, migration, and tube-like structure formation of human umbilical vein endothelial cells. Moreover, subconjunctival injection of BEV@MSN-CsA@Thermogel significantly inhibits corneal neovascularization in terms of the CNV area, the new vessel length, the corneal opaque area, the corneal inflammation and abnormal fibrosis in a rabbit model. This nanohybrid is thus a promising alternative for effective CNV treatment.

Nitric Oxide Interaction with the Eye

Nitric oxide (NO) is acknowledged as a vital intercellular messenger in multiple systems in the body. Medicine has focused on its functions and therapeutic applications for decades, especially in cardiovascular and nervous systems, and its role in immunological responses. This review was composed to demonstrate the prevalence of NO in components of the ocular system, including corneal cells and multiple cells in the retina. It discussed NO's assistance during the immune, inflammation and wound-healing processes. NO is identified as a vascular endothelial relaxant that can alter the choroidal blood flow and prompt or suppress vascular changes in age-related macular degeneration and diabetes, as well as the blood supply to the optic nerve, possibly influencing the progression of glaucoma. It will provide a deeper understanding of the role of NO in ocular homeostasis, the delicate balance between overproduction or underproduction and the effect on the processes from aqueous outflow and subsequent intraocular pressure to axial elongation and the development of myopia. This review also recognized the research and investigation of therapies being developed to target the NO complex and treat various ocular diseases.

Nanomedicines for the treatment of glaucoma: Current status and future perspectives

Glaucoma is the global leading cause of irreversible blindness. It is a chronic progressive disorder and, therefore, often requires long-term management with drugs on patients' discretion. However, there is a shortage of antiglaucoma drugs in the current market due to their low bioavailability. This is because there are multiple biological barriers of the human eyes, thereby leading to increased demands for frequent dosage regimen per day of these drugs, which could result in concomitant side effects and eventually reduced patient compliance. Recently, nanomedicines have become optimized alternatives to conventional ophthalmic formulations due to advantages of improved barrier permeability, sustained drug release, tissue targeting, and lowered systemic absorption of instilled medications. These merits provide the active ingredients in these nanomedicines an effective manner to reach the ideal concentrations at sites of damaged nerves, offering a promising platform for neuroprotective treatment of these conditions. In this study, nanomedicines and nanomedicine-based novel strategies for pharmacotherapy of glaucoma were reviewed, including liposomes, niosomes, nanoparticles, and dendrimers. This article intends to offer a comprehensive review of frontier progresses as well as hotspots and issues that appeared in the field of nanomedicines, which may enable a practical flourish in the future. STATEMENT OF SIGNIFICANCE: Recent novel pharmaceutical strategies toward glaucoma, a chronic blinding ocular disease that currently requires frequent daily dosage regimen, based on nanomedicines and nanomaterials have been comprehensively reviewed in this manuscript. The collection of field hotspots and issues in the late years should offer a quick grasp of the general concept and up-to-date threads upon the refinement of existing treatment patterns for glaucoma. Meanwhile, the Conclusion and Future Perspective section given at the end of the text brings out the possible shortages and opinions in terms of ideal research direction, which hopefully could facilitate a future practical flourish in the area.

Polymeric Nitric Oxide Delivery Nanoplatforms for Treating Cancer, Cardiovascular Diseases, and Infection

The shortened Abstract is as follows: Therapeutic gas nitric oxide (NO) has demonstrated the unique advances in biomedical applications due to its prominent role in regulating physiological/pathophysiological activities in terms of vasodilation, angiogenesis, chemosensitizing effect, and bactericidal effect. However, it is challenging to deliver NO, due to its short half-life (<5 s) and short diffusion distances (20-160 µm). To address these, various polymeric NO delivery nanoplatforms (PNODNPs) have been developed for cancer therapy, antimicrobial and cardiovascular therapeutics, because of the important advantages of polymeric delivery nanoplatforms in terms of controlled release of therapeutics and the extremely versatile nature. This reviews highlights the recent significant advances made in PNODNPs for NO storing and targeting delivery. The ideal and unique criteria that are required for PNODNPs for treating cancer, cardiovascular diseases and infection, respectively, are summarized. Hopefully, effective storage and targeted delivery of NO in a controlled manner using PNODNPs could pave the way for NO-sensitized synergistic therapy in clinical practice for treating the leading death-causing diseases.

Micro/nanodevices for assessment and treatment in stomatology and ophthalmology

Micro/nanodevices have been widely applied for the real-time monitoring of intracellular activities and the delivery of exogenous substances in the past few years. This review focuses on miniaturized micro/nanodevices for assessment and treatment in stomatology and ophthalmology. We first summarize the recent progress in this field by examining the available materials and fabrication techniques, device design principles, mechanisms, and biosafety aspects of micro/nanodevices. Following a discussion of biochemical sensing technology from the cellular level to the tissue level for disease assessment, we then summarize the use of microneedles and other micro/nanodevices in the treatment of oral and ocular diseases and conditions, including oral cancer, eye wrinkles, keratitis, and infections. Along with the identified key challenges, this review concludes with future directions as a small fraction of vast opportunities, calling for joint efforts between clinicians and engineers with diverse backgrounds to help facilitate the rapid development of this burgeoning field in stomatology and ophthalmology.

Nitric oxide donating anti-glaucoma drugs: advances and prospects

Glaucoma is a disease that causes irreversible blindness. Reducing intraocular pressure (IOP) is the main treatment at present. Nitric oxide (NO), an endogenous gas signaling molecule, can increase aqueous humor outflow facility, inhibit aqueous humor production thereby reducing IOP, as well as regulate eye blood flow and protect the optic nerve. Therefore, NO donating anti-glaucoma drugs have broad research prospects. In this review, we summarize NO-mediated therapy for glaucoma, and the state of the art of some NO donating molecules, including latanoprostene bunod in market and some other candidate compounds, for the intervention of glaucoma, as well as prospects and challenges ahead in this field.

Macromolecular Platform with Super-Cation Enhanced Trans-Cornea Infiltration for Noninvasive Nitric Oxide Delivery in Ocular Therapy

The cornea provides important protection for human eyes from invasion of alien substances. However, its blockage on the infiltration of molecules also constitutes a great challenge for noninvasive trans-cornea delivery of drugs. Here we report polyamino acid-based S-nitrosothiols with high cationic charge density as a NO carrier to overcome cornea associated blockage in ophthalmological therapy. Our results demonstrate that the cationic nature of the polymer promoted transcytosis, which greatly enhances the trans-cornea delivery of the NO donor and bypasses cornea barriers on passive drug diffusion. The combination of super cation and glutathione responsiveness synergistically enhanced intraocular delivery of topically administered poly(2-acetamido-N-triethylenetetramine-3-nitrosothiol-3-methylbutanamide)aspartamide, effectively alleviating high intraocular pressure in mice with glaucoma. Such a noninvasive "barrier hopping" approach not only serves as an inspiration in improving the efficiency of trans-cornea drug delivery but also has great potential in overcoming drug transporting barriers in other biomedical applications.

Emerging Trends in Nanomedicine for Improving Ocular Drug Delivery: Light-Responsive Nanoparticles, Mesoporous Silica Nanoparticles, and Contact Lenses

Vision is the most dominant of our senses, and it is crucial in every stage of our lives. Ocular diseases, regardless of whether they cause vision impairment or not, lead to personal and financial hardships. The anatomy and physiology of the eye strongly limit the efficacy of current ocular drug delivery strategies. Nanotechnology has been the ground for the development of powerful strategies in several fields, namely in medicine. This review highlights emerging nanotechnology-based solutions for improving ocular drug delivery and thus the bioavailability and efficacy of drugs. We focus our review on ambitious but promising approaches currently emerging to leverage the efficacy of nanoparticle-based systems in ocular therapy: (i) light-responsive nanoparticles, which enable spatiotemporal control of drug release; (ii) mesoporous silica nanoparticles, which offer high surface area-to-volume ratio, simple surface modification, good biocompatibility, and improved bioavailability; and (iii) contact lenses, which serve as a compliant method of nanoparticles use and as drug delivery systems for the treatment of ocular diseases.

Photothermally triggered nitric oxide nanogenerator targeting type IV pili for precise therapy of bacterial infections

Nitric oxide (NO) is an important biological messenger involved in the treatment of bacterial infections, but its controlled and targeted release in bacterial infections remains a major challenge. Herein, an intelligent NO nanogenerator triggered by near-infrared (NIR) light is constructed for targeted treatment of P. aeruginosa bacterial infection. Since maleimide can recognize and attach to the pilus of T4P of P. aeruginosa, we adopt this strategy to achieve the accurate release of therapeutic drugs at the infection site, i.e., after maleimide targets Gram-negative bacteria, the SNP@MOF@Au-Mal nanogenerator will release NO and generate ROS in situ from the inorganic photosensitizer gold nanoparticles under NIR irradiation to achieve synergistic antibacterial effect. In vivo experiments proved that the bacterial burden on the wound was reduced by 97.7%. Additionally, the nanogenerator was shown to promote the secretion of growth factors, which play a key role in regulating inflammation and inducing angiogenesis. This strategy has the advantage of generating a high concentration of NO in situ to promote the transfer of more NO and its derivatives (N₂O₃, ONOO^-) to bacteria, thereby significantly improving the antibacterial effect. The multifunctional antibacterial platform has been demonstrated as a good carrier for gas therapy because of its simple and efficient gas release performance, indicating its great potential for the treatment of drug-resistant bacterial infections.

The vital role for nitric oxide in intraocular pressure homeostasis

Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.

Glaucoma: Management and Future Perspectives for Nanotechnology-Based Treatment Modalities

Glaucoma, being asymptomatic for relatively late stage, is recognized as a worldwide cause of irreversible vision loss. The eye is an impervious organ that exhibits natural anatomical and physiological barriers which renders the design of an efficient ocular delivery system a formidable task and challenge scientists to find alternative formulation approaches. In the field of glaucoma treatment, smart delivery systems for targeting have aroused interest in the topical ocular delivery field owing to its potentiality to oppress many treatment challenges associated with many of glaucoma types. The current momentum of nano-pharmaceuticals, in the development of advanced drug delivery systems, hold promises for much improved therapies for glaucoma to reduce its impact on vision loss. In this review, a brief about glaucoma; its etiology, predisposing factors and different treatment modalities has been reviewed. The diverse ocular drug delivery systems currently available or under investigations have been presented. Additionally, future foreseeing of new drug delivery systems that may represent potential means for more efficient glaucoma management are overviewed. Finally, a gab-analysis for the required investigation to pave the road for commercialization of ocular novel-delivery systems based on the nano-technology are discussed.

Prolonged use of nitric oxide donor sodium nitroprusside induces ocular hypertension in mice

Nitric oxide (NO) donors are promising therapeutic candidates for treating intraocular hypertension (IOP) and glaucoma. This study aims to investigate the effect of prolonged use of NO donor sodium nitroprusside (SNP) on IOP. Since SNP has a short biological half-life, a nanoparticle drug delivery system (mesoporous silica nanoparticles) has been used to deliver SNP to the target tissues (trabecular meshwork and Schlemm's canal). We find that the sustained use of NO donor initially reduced IOP followed, surprisingly, by IOP elevation, which could not recover by drug withdraw but could be reversed by the antioxidant MnTMPyP application. The IOP elevation and normalization coincide with increased and reduced protein nitration in the mouse conventional outflow tissue. These findings suggest that the prolonged use of NO donor SNP may be problematic as it can cause outflow tissue damage by protein nitration. MnTMPyP is protective of the nitrative damage which could be considered to be co-applied with NO donors.

Influence of the Surface Functionalization on the Fate and Performance of Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles have been broadly applied as drug delivery systems owing to their exquisite features, such as excellent textural properties or biocompatibility. However, there are various biological barriers that prevent their proper translation into the clinic, including: (1) lack of selectivity toward tumor tissues, (2) lack of selectivity for tumoral cells and (3) endosomal sequestration of the particles upon internalization. In addition, their open porous structure may lead to premature drug release, consequently affecting healthy tissues and decreasing the efficacy of the treatment. First, this review will provide a comprehensive and systematic overview of the different approximations that have been implemented into mesoporous silica nanoparticles to overcome each of such biological barriers. Afterward, the potential premature and non-specific drug release from these mesoporous nanocarriers will be addressed by introducing the concept of stimuli-responsive gatekeepers, which endow the particles with on-demand and localized drug delivery.

Porous materials as carriers of gasotransmitters towards gas biology and therapeutic applications

This review highlights the strategies employed to load and release gasotransmitters such as NO, CO and H₂S from different kinds of porous materials, including zeolites, mesoporous silica, metal–organic frameworks and protein assemblies.

Cubic and hexagonal liquid crystal gels for ocular delivery with enhanced effect of pilocarpine nitrate on anti-glaucoma treatment

The objective of this work was to investigate phytantriol-based liquid crystal (LC) gels including cubic (Q₂) and hexagonal (H₂) phase for ocular delivery of pilocarpine nitrate (PN) to treat glaucoma. The gels were produced by a vortex method and confirmed by crossed polarized light microscopy, small-angle X-ray scattering, and rheological measurements. Moreover, the release behaviors and permeation results of PN from the gels were estimated using in vitro studies. Finally, the anti-glaucoma effect of LC gels was evaluated by in vivo animal experiments. The inner structure of the gels was Pn3m-type Q₂ and H₂ phase, and both of them showed pseudoplastic fluid properties based on characterization techniques. In vitro release profiles suggested that PN could be sustainably released from LC gels within 48 h. Compared with eye drops, Q₂ and H₂ gel produces a 5.25-fold and 6.23-fold increase in the P_app value (p < .05), respectively, leading to a significant enhancement of corneal penetration. Furthermore, a good biocompatibility and longer residence time on precorneal for LC gels confirmed by in vivo animal experiment. Pharmacokinetic studies showed that LC gels could maintain PN concentration in aqueous humor for at least 12 h after administration and remarkably improve the bioavailability of drug. Additionally, in vivo pharmacodynamics studies indicated that LC gels had a more significant intraocular pressure-lowering and miotic effect compared to eye drops. These research findings hinted that LC gels would be a promising pharmaceutical strategy for ocular application to enhance the efficacy of anti-glaucoma.