Silica-coated graphene compared to Si-CdSe/ZnS quantum dots: Toxicity, emission stability, and role of silica in the uptake process for imaging purposes.

Quantum dots (QDs) present a special type of nanocrystals (NCs) due to their unique optical and chemical properties. While cadmium-based QDs (Cd-QDs) have the most favorable physicochemical properties, their toxicity, instability in the aqueous phase, and loss of brightness at high temperature are some of the obstacles that prevent the wide use of Cd-QDs. Carbon-based QDs as graphene quantum dots (GQDs) represent a very promising biocompatible replacement.

Spectroscopic and photostability study of water-soluble hypericin encapsulated with polyvinylpyrrolidone.

Hypericin has gained great attention as a powerful photosensitizing and fluorescent agent for photodynamic therapy (PDT) and fluorescence diagnosis (FD) of cancer. However, native hypericin is hydrophobic and nearly insoluble in aqueous media which hinders its photobiological activity. Herein, we demonstrate the encapsulation of hypericin and polyvinylpyrrolidone (hypericin@PVP) as an attractive class of water-soluble formula of hypericin with improved absorption and emission characteristics in water.

IR-enhanced photothermal therapeutic effect of graphene magnetite nanocomposite on human liver cancer HepG2 cell model.

Graphene magnetite nanocomposites (G/FeO) exhibit light photothermal conversion upon enhancement by 808 nm IR laser excitation. We evaluated the cytotoxic and photothermal effects of G/FeO on a HepG2 human liver cancer cell model. Graphene nanosheets (rGO), magnetite nanoparticles (FeO), and G/FeO were prepared by chemical methods and characterized using transmission electron microscopy, Raman spectroscopy, zeta analysis, and vibrating sample magnemeter.

Photothermal versus photodynamic treatment for the inactivation of the bacteria Escherichia coli and Bacillus cereus: An in vitro study.

The widespread occurrence of microbial pathogens, including multidrug-resistant (MDR) bacteria, has ignited research efforts to discover alternative strategies to combat infections in patients. Recently, photodynamic therapy (PDT) and photothermal therapy (PTT) have been proposed for the inactivation of pathogens. Although PDT and PTT are very promising antipathogenic tools, further effort is needed to determine their real impact on pathogens apart from the effects of individual elements involved in the photodynamic/photothermal processes, i.

One-step synthesis of phyto-polymer coated gold nanospheres as a delivery system to enhance resveratrol cytotoxicity.

This study introduces a simple method for one-step synthesis of highly stable nontoxic polymer-coated gold nanospheres for use in drug delivery, focuses on the ability of chloroauric acid (HAu ) to induce polyphenols polymerization, puts up an easy procedure for loading hydrophobic drugs onto gold nanoparticles with ultra-high loading efficiency and studies the cytotoxicity of free and gold nanoparticles-loaded resveratrol. Gold nanospheres were synthesized simply by direct reaction between resveratrol itself and HAu in aqueous medium. Synthesized gold nanospheres exhibited high stability in both aqueous and ethanolic solutions.

Effect of Novel Quercetin Titanium Dioxide-Decorated Multi-Walled Carbon Nanotubes Nanocomposite on Bacillus subtilis Biofilm Development.

The present work was targeted to design a surface against cell seeding and adhering of bacteria, . A multi-walled carbon nanotube/titanium dioxide nano-power was produced via simple mixing of carbon nanotube and titanium dioxide nanoparticles during the sol-gel process followed by heat treatment. Successfully, quercetin was immobilized on the nanocomposite via physical adsorption to form a quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite.

Gelatin nanoparticles enhance delivery of hepatitis C virus recombinant NS2 gene.

Background: Development of an effective non-viral vaccine against hepatitis C virus infection is of a great importance. Gelatin nanoparticles (Gel.NPs) have an attention and promising approach as a viable carrier for delivery of vaccine, gene, drug and other biomolecules in the body.

Synthesis, Characterization and Cytotoxic Evaluation of Graphene Oxide Nanosheets: In Vitro Liver Cancer Model.

Background: Graphene nanosheets have a broad spectrum of biomedical applications. Hepatocellular cancer (HCC) is a major health problem in the Egyptian population. Currently, treatment strategies are invasive and have several adverse side effects.

Silver nanoparticles: Antimicrobial activity, cytotoxicity, and synergism with N-acetyl cysteine.

The fast progression of nanotechnology has led to novel therapeutic interventions. Antimicrobial activities of silver nanoparticles (Ag NPs) were tested against standard ATCC strains of Staphylococcus aureus (ATCC 9144), Escherichia coli (O157:H7), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 90028) in addition to 60 clinical isolates collected from cancer patients. Antimicrobial activity was tested by disk diffusion method and MIC values for Ag NPs alone and in combination with N-acetylcysteine (NAC) against tested pathogens were determined by broth microdilution method.

Application of quercetin and its bio-inspired nanoparticles as anti-adhesive agents against Bacillus subtilis attachment to surface.

The aim of this study was directed to reveal the repulsive effect of coated glass slides by quercetin and its bio-inspired titanium oxide and tungsten oxide nanoparticles on physical surface attachment of Bacillus subtilis as an ab-initio step of biofilm formation. Nanoparticles were successfully synthesized using sol-gel and acid precipitation methods for titanium oxide and tungsten oxide, respectively (in the absence or presence of quercetin). The anti-adhesive impact of the coated-slides was tested through the physical attachment of B.

Effect of size, concentration, and type of spherical gold nanoparticles on heat evolution following laser irradiation using tissue-simulating phantoms.

Photothermal therapy has recently gained a considerable attention particularly after the revolution of nanomaterials and nanotechnology. The aim of the present study is to assess the optimal photothermal response through investigating some effective parameters of spherical gold nanoparticles (AuNPs), e.g.

Subcellular toxicity of gold nanoparticles irradiated with 532 nm pulsed laser.

Objective: Prior to plasmonic photothermal therapy, involving heating of gold nanoparticles (GNPs) by laser, we explored some subcellular events that may threaten the viability of rat kidney cells (RKCs) incubated with GNPs irradiated with pulsed laser.

Background Data: We have previously shown a decrease in the viability of RKCs, on incubation with GNPs irradiated with pulsed laser. This decrease in viability was concomitant to a reduction in GNP diameter size, and reflected the occurrence of subcellular toxic events.

Laser-induced modifications of gold nanoparticles and their cytotoxic effect.

As nanotechnology continues to develop, an assessment of nanoparticles' toxicity becomes very crucial for biomedical applications. The current study examines the deleterious effects of pre-irradiated gold nanoparticles (GNPs) solutions on primary rat kidney cells (PRKCs). Spectroscopic and transmission electron microscopic studies demonstrated that exposure of 15 nm GNPs in size to pulsed laser caused a reduction both in optical density and mean particle diameter.

Biophysical characterization of gold nanoparticles-loaded liposomes.

Gold nanoparticles were prepared and loaded into the bilayer of dipalmitoylphosphatidylcholine (DPPC) liposomes, named as gold-loaded liposomes. Biophysical characterization of gold-loaded liposomes was studied by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy as well as turbidity and rheological measurements. FTIR measurements showed that gold nanoparticles made significant changes in the frequency of the CH(2) stretching bands, revealing that gold nanoparticles increased the number of gauche conformers and create a conformational change within the acyl chains of phospholipids.

Low power argon laser-induced thermal therapy for subcutaneous Ehrlich carcinoma in mice using spherical gold nanoparticles.

The present study examines the feasibility of a low power argon laser-induced thermal therapy to Ehrlich carcinoma, employing a direct administration of spherical gold nanoparticles (GNPs). This modality utilizes the advantage of strong surface plasmon resonance exhibited by spherical GNPs in the visible range. Ehrlich tumors were grown in female balb mice by subcutaneous injection of Ehrlich ascites carcinoma cells.

Evaluation of hypericin-loaded solid lipid nanoparticles: physicochemical properties, photostability and phototoxicity.

Hypericin (HYP), a natural photosensitizer, has powerful photo-oxidizing ability, tumor-seeking characteristics, and minimal dark toxicity; nevertheless, it has proven high lipid solubility compared to its sparingly water soluble nature. Therefore, its formulation into solid lipid nanoparticles (SLNs) has attracted increasing attention as a potential drug-delivery carrier. Two HYP-loaded SLNs formulations were prepared utilizing microemulsion-based technique.

Photodynamic efficacy of hypericin targeted by two delivery techniques to hepatocellular carcinoma cells.

The photocytotoxic effect of hypericin (Hyp) targeted by two different delivery techniques, namely, liposomes and anti-hepatocyte specific antigen (anti-HSA) was investigated. Optical absorption and steady-state fluorescence were used to analyze the conjugation of Hyp with anti-HSA model and to evaluate the encapsulation capacity and drug release in a liposome model. Particle size and thermal analysis of the prepared liposomes were performed using laser-light scattering and differential scanning calorimetry (DSC), respectively.

Photosensitized effects of Rose Bengal on structure and function of lens protein "alpha-crystallin".

The conformational changes of the bovine lens protein "alpha-crystallin" have been investigated in the presence of the photosensitizer Rose Bengal (RB), in the dark as well as after visible light irradiation. Absorption and fluorescence emission spectra of RB [5 x 10(-6) M] and Fourier transform-IR spectra of alpha-crystallin [5 mg mL(-1)] were significantly altered upon RB alpha-crystallin complex formation. RB was found to bind to alpha-crystallin in a molecular pocket characterized by a low polarity, with Trp most likely involved in this interaction.

Fluorescence study on the interaction between hypericin and lens protein "alpha-crystallin".

Hypericin has been reported as a potent photosensitizing agent exhibiting antiviral, antibacterial, antineoplastic activities. Although its photophysics and mode of action are strongly modulated by the binding protein, detailed information about its mechanism of interaction with possible cellular targets, including proteins, is still lacking. Previous in vitro studies demonstrated that hypericin can be uptaken by intact lens and is able to bind to the major lens protein "alpha-crystallin.

Photosensitized structural modifications of the lens protein alpha-crystallin: do all modifications impair chaperone-like activity?

Among chaperone-like functioning proteins, the lens alpha-crystallins are of particular interest because they are not renewed, and even minor alterations can hurt their function of maintaining the proper refractive index and avoiding cataract formation in the lens. Several reports have suggested the occurrence of remarkable structural modifications in lens proteins in the presence of endogenous and exogenous sensitizers upon exposure to light. In particular, it has been shown in vitro that hypericin, the active ingredient of Hypericum, can bind to and, in the presence of light, cause the photopolymerization of alpha-crystallin.