Base-triggerable lauryl sarcosinate-dodecyl sulfate catanionic liposomes: structure, biophysical characterization, and drug entrapment/release studies.

Equimolar mixtures of oppositely charged single-chain amphiphiles form a variety of phases, including vesicles. Such catanionic mixed lipid systems show high stability and exhibit versatile physicochemical properties. In the present study we have investigated the aggregation behaviour of lauryl sarcosinate hydrochloride (LS·HCl) in aqueous dispersion as well as its interaction with the anionic surfactant sodium dodecyl sulfate (SDS). The CMC of LS·HCl was estimated to be ∼5 mM by isothermal titration calorimetry (ITC) and fluorescence spectroscopy using pyrene as the fluorescent probe. Turbidimetric and ITC studies on the interaction of LS·HCl with SDS demonstrated that the two surfactants form an equimolar catanionic complex. The crystal structure of the lauryl sarcosinate-dodecyl sulfate (LS-DS) complex revealed that the complex is stabilized by classical N-H⋯O as well as C-H⋯O hydrogen bonds, besides the electrostatic attraction between LS (cation) and DS (anion) and dispersion interactions between the hydrocarbon chains. Differential scanning calorimetry studies revealed that the phase transition of the equimolar LS-DS complex is significantly reduced compared to the analogous LG-DS and LA-DS complexes in the fully hydrated state. Dynamic light scattering, atomic force microscopy and transmission electron microscopy studies demonstrated that the LS-DS catanionic complex forms stable medium-sized vesicles (diameter of ∼300-500 nm). In vitro studies with 5-fluorouracil and rhodamine 6G showed efficient entrapment and release of these two anti-cancer drugs in the physiologically relevant pH range of 6.0-8.0, but with contrasting pH dependences. These observations indicate that LS-DS catanionic vesicles may find application in designing drug delivery systems.

Red-emitting carbon nanoparticles with unprecedented singlet oxygen generation efficiency for cancer theranostics.

Fluorescent Red-emitting carbon nanoparticles (RCNPs) are produced by an economical and green hydrothermal method using Eucalyptus leaves as a precursor. This is the first report of its kind demonstrating RCNPs in combined PDT-Chemo combination therapy, as RCNPs bind with mitoxantrone (MTO) electrostatically. The synthesized RCNPs before and after conjugation of MTO are characterised using DLS, SEM, TEM, UV-Vis, Fluorescence, FTIR, and 1H NMR Spectroscopy. FTIR and 1H NMR confirm the interaction between -NH proton of MTO with carboxylic acid oxygen of RCNPs. RCNPs are demonstrated as brightly fluorescent, type II photosensitizer (PS) with an extraordinary 1O2 quantum yield of 0.96, when triggered with a red laser at 660 nm. Moreover, the biocompatibility of RCNPs and RCNPs-MTO are examined and confirmed by performing a cytotoxicity assay on MCF-7 cell lines. Subsequently, to explore the internalization process of the RCNPs as a function of concentration, confocal imaging study is also carried out. The cell viability and the apoptosis assay indicates that RCNPs-MTO can achieve the PDT-Chemo synergistic cancer therapy. To the best of our knowledge, this is the first time that Eucalyptus leaves, a natural source of great abundance, is used as raw material and applied for combined PDT-chemotherapy.

A metal-enhanced fluorescence sensing platform for selective detection of picric acid in aqueous medium.

Apart from national security and military purposes, it is also of great importance to detect picric acid (PA) in aqueous solution for pollution control. Herein, we report a gold nanoparticle (AuNP)-based sensor for detection of PA in aqueous condition, based on metal-enhanced fluorescence (MEF) of poly(allylamine)hydrochloride (PAH). Notable enhancement in fluorescence intensity is observed when PAH is incubated with Au@SiO2 nanoparticles, where silica shell controls the distance between gold core and PAH. Almost ∼280 fold enhancement is recorded when PAH is incubated with ∼45 nm diameter Au nanoparticles. A significant reduction in excited state lifetime followed the enhancement in fluorescence intensity, identifying the mechanism to be primarily obtained from the intrinsic radiative decay rate enhancement of PAH. The MEF sensor shows excellent selectivity for detection of PA in water, among similar electron deficient compounds via fluorescence quenching. The detection limit of the sensor is calculated to be 79 nM, in the linear range. Detection of PA is demonstrated in simulated water samples, where matrix effects are taken into account to assess the efficacy of the sensor.

Green Synthesis of Full-Color Fluorescent Carbon Nanoparticles from Eucalyptus Twigs for Sensing the Synthetic Food Colorant and Bioimaging.

Full-color fluorescent carbon nanoparticles (CNPs) are produced by a facile and green hydrothermal method followed by the differential washing technique. Eucalyptus twigs are used as a precursor to synthesize multiemissive light blue, blue, green, and red CNPs. Brilliant Blue FCF (BB) is a widely used synthetic food colorant, which is toxic for the human body, when consumed beyond the permitted limit. Herein, we demonstrate light blue CNPs as a sensor for selective and sensitive detection of BB via a fluorescence quenching mechanism with a limit of detection of 200 nM. Temperature-dependent fluorescence and 1H NMR studies confirmed the mechanism as combined dynamic and static quenching. To demonstrate the practical efficacy of the sensor, BB is effectively detected and estimated in selected food samples procured from the market. Moreover, the biocompatibility of light blue and blue CNPs is examined and confirmed by performing a cytotoxicity assay on MDA-MB-231 cell lines. Subsequently, the cellular imaging study is also carried out to explore the internalization process of the CNPs as a function of concentration. To the best of our knowledge, this is the first time that Eucalyptus twigs, a natural source of high abundance, are used as raw materials and valorized for sensing artificial food color and bioimaging purposes.

Synthesis, Detailed Characterization, and Dual Drug Delivery Application of BSA Loaded Aquasomes.

Aquasomes (AQ) are self-assembled nanostructures, made up of a spherical hydroxyapatite core and a carbohydrate layer on top, for delivering bioactive molecules like proteins, peptides, etc., which are adsorbed on the carbohydrate layer. This is the first report of its kind demonstrating AQ as an efficient dual drug delivery system, capable of releasing bioactive molecule and a hydrophobic drug together. The synthesized AQ before and after adsorption of the bioactive molecule are characterized using dynamic light scattering, scanning electron microscopy, X-ray diffraction, small-angle X-ray scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and Raman spectroscopy. BSA (bovine serum albumin) protein is used as the model bioactive molecule for the in vitro dual release studies along with representative hydrophobic drugs Coumarin 153 (C153), Warfarin (WAR), and Ibuprofen (IBU). The release behaviors of the hydrophobic drugs are explained by studying their binding interactions with BSA. The binding interactions of the drugs with BSA are analyzed by carrying out fluorescence quenching experiment of BSA, site marking competition experiment, anisotropy, and ET (30) studies. Further, in vitro biocompatibility studies are performed for dually loaded AQ by using hemolysis assay. The hemolysis assay do not show any lysing of the red blood cells, suggesting the formulations to be clinically capable for administration.