Photothermal and selective microbial inactivation behaviors of gluconamide-coated IR780 nanoparticles

Photothermal therapy (PTT) is a promising alternative treatment for bacterial infection. In this study, a photothermal nanoparticle was prepared by encapsulating IR780 into N-octyl-D-gluconamide (GA). The photothermal nanoparticle (IR780-GA NP) was evenly suspended in water with an average particle size of 42.2 nm. After exposure to near-infrared light, the temperature of the IR780-GA NP suspension was increased by around 15 °C within 5 min. This leads to an obvious microbial inactivation effect when it is adsorbed to methicillin-resistant Staphylococcus aureus (MRSA, 2 orders of magnitude reduction of CFU concentration) and Escherichia coli (1.5 orders of magnitude reduction of CFU concentration). Interestingly, Salmonella typhimurium survived after the same treatment. Different strains also showed variations. The hemolysis test showed that IR780-GA NPs had good blood compatibility. In vivo experiments collaborated with the in vitro findings. The IR780-GA NP-triggered photothermal effects killed 63-100% of bacteria in the wound site of mice depending on the IR780-GA NP concentration. Overall, this study provided the fundamental basis of IR780-GA NPs in four aspects: fabrication, photothermal characterization, selective adsorption, and microbial inactivation (in vitro and in vivo). The findings of this study provide a practical approach for the development of mild photothermal therapy which targets specific bacterial strains and treats MRSA infection effectively.

An overview of current alternative models in the context of ocular surface toxicity

The 21st century has seen a steadily increasing social awareness of animal suffering, with increased attention to ethical considerations. Developing new integrated approaches to testing and assessment (IATA) strategies is an Organisation for Economic Co-operation and Development (OECD) goal to reduce animal testing. Currently, there is a lack of alternative models to test for ocular surface toxicity (aside from irritation) in lieu of the Draize eye irritation test (OECD guideline No. 405) performed in rabbits. Five alternative in vitro or ex vivo methods have been validated to replace this reference test, but only in combination. However, pathologies like Toxicity-Induced Dry Eye (TIDE), cataract, glaucoma, and neuropathic pain can occur after exposure to a pharmaceutical product or chemical and therefore need to be anticipated. To do so, new models of lacrimal glands, lens, and neurons innervating epithelia are required. These models must take into account real-life exposure (dose, time, and tear film clearance). The scientific community is working hard to develop new, robust, alternative, in silico, and in vitro models, while attempting to balance ethics and availability of biological materials. This review provides a broad overview of the validated methods for analyzing ocular irritation and those still used by some industries, as well as promising models that need to be optimized according to the OECD. Finally, we give an overview of recently developed innovative models, which could become new tools in the evaluation of ocular surface toxicity within the scope of IATAs.

Topical ocular delivery of vancomycin loaded cationic lipid nanocarriers as a promising and non-invasive alternative approach to intravitreal injection for enhanced bacterial endophthalmitis management

Vancomycin (VCM) is a drug of choice for treating infections caused by Staphylococcus species, reported being the most causative agent of bacterial endophthalmitis. However, the ocular bioavailability of topically applied VCM is low due to its high molecular weight and hydrophilicity. The current study sought to explore whether the nanostructured lipid carriers (NLCs) fabricated via cold homogenization technique could improve ocular penetration and prolong the ophthalmic residence of VCM. A 2³ full factorial design was adopted to evaluate the influence of different process and formulation variables on VCM-loaded NLC formulae. The optimized formula with the particle size of 96.4 ± 0.71 nm and narrow size distribution showed spherical morphology obtained by AFM and represented sustained drug release up to 67% in 48 h fitted to the Korsmeyer-Peppas model with probably non-Fickian diffusion kinetic. FTIR studies visualized the drug-carrier interactions in great detail. High encapsulation of VCM (74.8 ± 4.3% w/w) in NLC has been established in DSC and PXRD analysis. The optimal positively charged (+ 29.7 ± 0.47 mV) colloidal dispersion was also stable for 12 weeks at both 4 °C and 25 °C. According to in vivo studies, incorporation of VCM in NLC resulted in a nearly 3-fold increase in the intravitreal concentration of VCM after eye-drop instillation over control groups. Besides, microbiological evaluation admitted its therapeutic effect within five days is comparable to intravitreal injection of VCM. Further, the optimized formula was found to be nonirritant and safe for ophthalmic administration in RBC hemolytic assay. Also, fluorescent tracking of NLCs on rabbit's cornea showed an increase in corneal penetration of nanoparticles. Thus, it is possible to infer that the evolved NLCs are promising drug delivery systems with superior attainments for enhanced Vancomycin ophthalmic delivery to the eye's posterior segment and improved bacterial endophthalmitis management.

Fabrication and Characterization of Chitosan/Poly(Lactic-Co-glycolic Acid) Core-Shell Nanoparticles by Coaxial Electrospray Technology for Dual Delivery of Natamycin and Clotrimazole

Natamycin (NAT) is the drug of choice for the treatment of fungal keratitis (FK). However, its inherent shortcomings, such as poor solubility, high dosing frequency, and long treatment cycle, need to be urgently addressed by designing a new delivery to widen its clinical utility. Growing research has confirmed that clotrimazole (CLZ) plays a significant role in fungal growth inhibition. Hence, coaxial electrospray (CO-ES) technology is used herein to prepare nano-systems with an average hydrodynamic particle size of 309-406 nm for the co-delivery of NAT and CLZ in chitosan (CTS) and poly(lactic-co-glycolic acid) (PLGA). The resulting NAT/CLZ@CTS/PLGA formulations were characterized by a transmission electron microscope (TEM) and in vitro release test. The results show that the formulations had obvious core-shell structures, uniform particle distribution, and also can sustain the release of drugs over 36 h. Furthermore, in vitro hemolysis, in vivo corneal irritation test, local allergenic test, and antifungal activity analyses are performed to evaluate the safety and efficiency of the formulations. Thus, good biosafety along with a significant anti-candidiasis effect are found in the NAT/CLZ@CTS/PLGA nanoparticles (NPs). Taken together, the results suggest that this design may provide a promising drug delivery system and a new option for the treatment of FK.

In vitro biocompatibility of a sandblasted, acid-etched HA composite coating on ultrafine-grained titanium

A sandblasted, acid-etching hydroxyapatite (SLA-HA) composite coating on ultrafine-grained titanium was synthesized by the sandblasting, acid etching and electrophoresis deposition. Mouse osteoblasts (MC3T3-E1) were cultured in vitro and inoculated on the SLA-HA composite coating of the ultrafine-grained titanium. Using ultrafine-grained titanium with SLA coating as the control group, the adhesion and proliferation of the osteoblasts were analyzed using the CCK-8 assay. The number and morphology of the cells were observed using a laser confocal microscope. Cells toxicity of the cytotoxicity to osteoblasts was studied by culturing them in an immersion solution of the SLA-HA composite coating. The hemolysis properties of the obtained material were assessed using fresh rabbit blood. Ultrafine-grained titanium with the SLA-HA composite coating was found to have no significant toxicity to osteoblasts, as well as good blood compatibility, playing a positive role in the adhesion of osteoblasts and promoting their proliferation and differentiation.

Evaluating Hemolytic and Photo Hemolytic Potential of Organophosphorus by In Vitro Method as an Alternative Tool Using Human Erythrocytes

AIMS

The present study aims to determine the phototoxic and haemolytic activity of organophosphorus. The use of alternative in vitro assays with human erythrocytes is suggested to predict the polluting effect of these products on health.

METHODOLOGY

Human erythrocytes from Toluca Blood Bank were used. Sodium dodecyl sulfate was employed as a positive control. Additionally, the haemolysis percentage of three organophosphate (Acetate, Chlorpyrifos, Malathion, Methamidophos, Methyl Parathion) induced photo haemolysis formulated with surfactants on a concentration of 2 x 109 erythrocytes were evaluated. Finally, the products were classified as irritant or phototoxic.

RESULTS

Results showed that the HC50 red blood cells were similar for each organophosphate (Malathion and Methamidophos) indicating very irritant action with ratio classification (L/D) of 0.041 and 0.053, respectively. On the other hand, Chlorpyrifos was classified as an irritant with L/D= 0.14. On the other hand, the HC50 obtained photo hemolysis assays irradiated red blood cells was similar for each organophosphate (Acetate, Chlorpyrifos, Malathion, Methamidophos, Methyl Parathion) indicating no phototoxic action.

CONCLUSION

As a conclusion, it can be said that the parameters of haemolysis and denaturation of proteins are good indicators to classify organophosphorus formulated with surfactants as irritating or phototoxic.

Prospective of Monascus Pigments as an Additive to Commercial Sunscreens

Red and yellow pigments from Monascus purpureus (NMCC-PF01) were evaluated to enhance sun protection factor (SPF) of commercial sunscreens and Aloe vera extract. The extracted Monascus pigments contain rubropunctamine (red pigment) and the mixture of monascin and ankaflavin (yellow pigment) as major components. Antioxidant activity and in-vitro safety of the pigments were assessed by ferric reduction potential and DPPH radical scavenging assays, human keratinocytes (HaCaT), and erythrocytes (RBCs) cytotoxicity assay, respectively. In results, SPF of commercial sunscreens showed an increase of 36.5% with red pigment compared to the 13% increase by yellow pigment. The in-vitro studies showed 67.6% ferric reducing potential and 27% DPPH radical scavenging activity, neither cytotoxic effect against human keratinocytes nor haemolytic activity. These results confirmed the safe nature of the Monascus pigments; however, in-vivo studies merit further research. In conclusion, screened pigments from Monascus purpureus may act as potential candidates to increase SPF of commercial sunscreen naturally.

Cyclodextrin Enhances Corneal Tolerability and Reduces Ocular Toxicity Caused by Diclofenac

With advances in refractive surgery and demand for cataract removal and lens replacement, the ocular use of nonsteroidal anti-inflammatory drugs (NSAIDs) has increased. One of the most commonly used NSAIDs is diclofenac (Diclo). In this study, cyclodextrins (CDs), α-, β-, γ-, and HP-β-CDs, were investigated with in vitro irritation and in vivo ulceration models in rabbits to reduce Diclo toxicity. Diclo-, α-, β-, γ-, and HP-β-CD inclusion complexes were prepared and characterized and Diclo-CD complexes were evaluated for corneal permeation, red blood cell (RBCs) haemolysis, corneal opacity/permeability, and toxicity. Guest- (Diclo-) host (CD) solid inclusion complexes were formed only with β-, γ-, and HP-β-CDs. Amphipathic properties for Diclo were recorded and this surfactant-like functionality might contribute to the unwanted effects of Diclo on the surface of the eye. Contact angle and spreading coefficients were used to assess Diclo-CDs in solution. Reduction of ocular toxicity 3-fold to16-fold and comparable corneal permeability to free Diclo were recorded only with Diclo-γ-CD and Diclo-HP-β-CD complexes. These two complexes showed faster healing rates without scar formation compared with exposure to the Diclo solution and to untreated groups. This study also highlighted that Diclo-γ-CD and Diclo-HP-β-CD demonstrated fast healing without scar formation.

Safety Assessment of Methyl Glucose Polyethers and Esters as Used in Cosmetics

The Cosmetic Ingredient Review Expert Panel (Panel) reviewed the safety of methyl glucose polyethers and esters which function in cosmetics as skin/hair-conditioning agents, surfactants, or viscosity increasing agents. The esters included in this assessment are mono-, di-, or tricarboxyester substituted methyl glucosides, and the polyethers are mixtures of various chain lengths. The Panel reviewed available animal and clinical data, including the molecular weights, log K_ows, and other properties in making its determination of safety on these ingredients. Where there were data gaps, similarities between molecular structures, physicochemical and biological characteristics, and functions and concentrations in cosmetics allowed for extrapolation of the available toxicological data to assess the safety of the entire group. The Panel concluded that there likely would be no significant systemic exposure from cosmetic use of these ingredients, and that these ingredients are safe in cosmetic formulations in the present practices of use and concentration.

Critical appraisal of alternative irritation models: three decades of testing ophthalmic pharmaceuticals

BACKGROUND

Testing ocular tolerability of ocular pharmaceuticals is an essential regulatory requirement. The current approved reference model (gold standard) for ocular irritation testing is the Draize test. However this method is subjective and involves using live animals, hence the need to develop alternative in vitro and ex vivo testing strategies.

SOURCE OF DATA

Pubmed, Science Direct, Scopus, Google Scholar, Medline, Current Content, Web of Science and validation reports from international regulatory bodies; The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) and European Centre for the Validation of Alternative Methods (ECVAM) were searched for in vitro alternatives.

AREA OF AGREEMENT

Whilst no single in vitro test can effectively replace the Draize eye irritation test, regulatory bodies and cosmetic/pharmaceutical industries agree that there is a need for in vitro alternatives with validated endpoints to evaluate pharmaceutical ingredients and finished eye products.

AREA OF CONTROVERSY

There is no single in vitro test / assay that can predict the ocular irritation potential of mild to moderate test substances.

AREA TIMELY FOR DEVELOPING RESEARCH

This review provides a critical appraisal of the selected in vitro and ex vivo ocular toxicity models recommended by international regulatory bodies. These include cytotoxicity methods, biochemical systems and ex vivo assays. The latter are approved by ECVAM as in vitro alternatives for the well-known Draize test. Hen's egg test-chorioallantoic membrane and the isolated rabbit eye test are also accepted by regulatory agencies in France, Germany, the Netherlands and the UK. A combination of ex vivo assays along with histological examination of excised bovine cornea can predict the conjunctival and corneal tolerability and cover a wider range of ocular pharmaceutical substances.

Estimation of the chemical-induced eye injury using a weight-of-evidence (WoE) battery of 21 artificial neural network (ANN) c-QSAR models (QSAR-21): part I: irritation potential

Evaluation of potential chemical-induced eye injury through irritation and corrosion is required to ensure occupational and consumer safety for industrial, household and cosmetic ingredient chemicals. The historical method for evaluating eye irritant and corrosion potential of chemicals is the rabbit Draize test. However, the Draize test is controversial and its use is diminishing - the EU 7th Amendment to the Cosmetic Directive (76/768/EEC) and recast Regulation now bans marketing of new cosmetics having animal testing of their ingredients and requires non-animal alternative tests for safety assessments. Thus, in silico and/or in vitro tests are advocated. QSAR models for eye irritation have been reported for several small (congeneric) data sets; however, large global models have not been described. This report describes FDA/CFSAN's development of 21 ANN c-QSAR models (QSAR-21) to predict eye irritation using the ADMET Predictor program and a diverse training data set of 2928 chemicals. The 21 models had external (20% test set) and internal validation and average training/verification/test set statistics were: 88/88/85(%) sensitivity and 82/82/82(%) specificity, respectively. The new method utilized multiple artificial neural network (ANN) molecular descriptor selection functionalities to maximize the applicability domain of the battery. The eye irritation models will be used to provide information to fill the critical data gaps for the safety assessment of cosmetic ingredient chemicals.

Quantum dots: an insight and perspective of their biological interaction and how this relates to their relevance for clinical use

Due to their novel physico-chemical characteristics, semi-conductor nanocrystal quantum dots (QDs) provide an advantageous perspective towards numerous different consumer and medical applications. The most notable potential application of QDs is their use as therapeutic and diagnostic tools in nanomedicine. Despite the many benefits posed by QDs, the proposed, intentional exposure to humans has raised concerns towards their potential impact upon human health. These concerns are predominantly based upon the heterogeneous composition of QDs, which most commonly comprises of a cadmium-based core and zinc sulphide shell. Whilst other nanoparticle (NP) types possess a similar structure to QDs (i.e. core-shell technology (e.g. Fe(2)O(3), Au and superparamagnetic iron oxide NPs)), the importance of the concerns surrounding human exposure to QDs is amplified further since, due to the sophisticated chemical and light-emitting properties of QDs, the use of these NPs within any (nano)medical setting/application could be suggested as realistic, rather than simply an advantageous possibility. It is therefore imperative that a thorough understanding of how QDs interact with various biological systems, predominantly those relative to humans and what the consequences of such interactions are is gained with extreme alacrity. It is the aim of this review to highlight the current knowledge base of QD-biological system interactions, where the knowledge gaps (still) remain and how the understanding of this interaction relates to the most notable of applications for QDs; their clinical relevance.