Template-directed hydrothermal synthesis of hydroxyapatite as a drug delivery system for the poorly water-soluble drug carvedilol

In order to improve the dissolution rate and increase the bioavailability of a poorly water-soluble drug, intended to be administered orally, the biocompatible and bioactive mesoporous hydroxyapatite (HA) was successfully synthesized. In the present study, mesoporous HA nanoparticles were produced using Pluronic block co-polymer F127 and cetyltrimethylammonium bromide (CTAB) as templates by the hydrothermal method. The obtained mesoporous HA was employed as a drug delivery carrier to investigate the drug storage/release properties using carvedilol (CAR) as a model drug. Characterizations of the raw CAR powder, mesoporous HA and CAR-loaded HA were carried out by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, N₂ adsorption/desorption, thermogravimetric analysis (TGA), and UV-VIS spectrophotometry. The results demonstrated that CAR was successfully incorporated into the mesoporous HA host. In vitro drug release studies showed that mesoporous HA had a high drug load efficiency and provided immediate release of CAR compared with micronized raw drug in simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.8). Consequently, mesoporous HA is a good candidate as a drug carrier for the oral delivery of poorly water-soluble drugs.     

Functional and unmodified MWNTs for delivery of the water-insoluble drug Carvedilol - A drug-loading mechanism

The purpose of this study was to develop carboxyl multi-wall carbon nanotubes (MWNTs) and unmodified MWNTs loaded with a poorly water-soluble drug, intended to improve the drug loading capacity, dissolubility and study the drug-loading mechanism. MWNTs were modified with a carboxyl group through the acid treatment. MWNTs as well as the resulting functionalized MWNTs were investigated as scaffold for loading the model drug, Carvedilol (CAR), using three different methods (the fusion method, the incipient wetness impregnation method, and the solvent method). The effects of different pore size, specific surface area and physical state were systematically studied using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), nitrogen adsorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The functional MWNTs allowed a higher drug loading than the unmodified preparations. The methods used to load the drug had a marked effect on the drug-loading, dissolution, and physical state of the drug as well as its distribution. In addition, the solubility of the drug was increased when carried by both MWNTs and functional MWNTs, and this might help to improve the bioavailability.     

Magnetic nanoemulsions as drug delivery system for Foscan: Skin permeation and retention in vitro assays for topical application in photodynamic therapy (PDT) of skin cancer

In this work, we performed the synthesis and in vitro characterization of a new class of drug delivery system (DDS) denominated magnetic nanoemulsion (MNE). The association of colloidal nanoparticles with biocompatible magnetic fluids results in a new DDS for application in photodynamic therapy (PDT) and magnetic hyperthermia treatment. It works in a synergic manner with an expected enhancement in tumor damage after minimum drug doses, based on heat dissipation and/or light photosensitization. For this purpose, we investigated the permeation and retention in vitro model using Foscan^® as a photosensitizer incorporated in MNE using a Franz diffusion cell and a biological skin model in biomimetic conditions.     

Elementary Process Theory: a formal axiomatic system with a potential application as a foundational framework for physics supporting gravitational repulsion of matter and antimatter

Theories of modern physics predict that antimatter having rest mass will be attracted by the earth's gravitational field, but the actual coupling of antimatter with gravitation has not been established experimentally. The purpose of the present research was to identify laws of physics that would govern the universe if antimatter having rest mass would be repúlsed by the earth's gravitational field. As a result, a formalized axiomatic system was developed together with interpretation rules for the terms of the language: the intention is that every theorem of the system yields a true statement about physical reality. Seven non‐logical axioms of this axiomatic system form the Elementary Process Theory (EPT): this is then a scheme of elementary principles describing the dynamics of individual processes taking place at supersmall scale. It is demonstrated how gravitational repulsion functions in the universe of the EPT, and some observed particles and processes have been formalized in the framework of the EPT. Incompatibility of Quantum Mechanics (QM) and General Relativity (GR) with the EPT is proven mathematically; to demonstrate applicability to real world problems to which neither QM nor GR applies, the EPT has been applied to a theory of the Planck era of the universe. The main conclusions are that a completely formalized framework for physics has been developed supporting the existence of gravitational repulsion and that the present results give rise to a potentially progressive research program.     

Development of a dual-wavelength dye-laser system for the UV and its application to simultaneous multi-element detection

In this paper, the design and performance characteristics of a pulsed tunable dye laser system for the simultaneous generation of two UV wavelengths are presented. The system is composed of an oscillator and an amplifier stage, pumped by the second harmonic of a commercial Nd:YAG laser. Dual-wavelength operation is achieved with one additional tuning mirror introduced to the prism expanded grazing incidence oscillator. The two obtained wavelengths are independently tunable, their separation is only limited by the gain profile of the dye. Both wavelengths are frequency doubled by Second-Harmonic Generation (SHG) in two KDP or BBO crystals. Performance characteristics such as bandwidth, efficiency, tuning range and wavelength separation are reported. As application two such systems are used for the simultaneous detection of the four elements cadmium, nickel, manganese and lead by Laser-Excited Atomic Fluorescence Spectrometry in a graphite furnace (ETA-LEAFS).     

非线性系统的任意项精细积分外插多步法及其在混沌数值分析中的应用

对非线性系统提出了高精度的精细积分任意项外插多步法的计算公式.本方法只需增加插值 项数即可提高计算精度，同时不会增加过大的计算量，发展完善了精细积分法.将本方法应 用于混沌方程中，取得了较好的效果.数值计算结果表明，该方法是一种高精度、高效率的 方法，在求解混沌系统上比传统方法有很大的优势. 关键词： 非线性系统 任意项精细积分多步法 混沌系统     

The co-luminescence effect of a europium (III)-lanthanum (III)-gatifloxacin-sodium dodecylbenzene sulfonate system and its application for the determination of trace amount of europium (III)

A novel co-luminescence system based on the formation of a complex between europium (III) (Eu³⁺) and gatifloxacin (GFLX) in sodium dodecylbenzene sulfonate (SDBS) micelle solution containing lanthanum (III) (La³⁺) has been developed for the determination of Eu³⁺. The experimental results show that the complex formed by Eu³⁺ and GFLX here can emit the characteristic luminescence of Eu³⁺. With the addition of La³⁺, the luminescence intensity of the system was enhanced about 7-fold compared with that without La³⁺. Under the optimal conditions, the luminescence intensity exhibits an excellent linear relationship with Eu³⁺ concentration in the range of 1.0×10⁻¹⁰-5.0×10⁻⁸ mol L⁻¹. The correlation coefficient (r) is 0.9998, and the detection limit (3σ) is 7.0×10⁻¹⁴ mol L⁻¹. A test method with satisfactory accuracy based on this system was applied to determine trace amounts of Eu³⁺ in rare earth samples. In addition, the detailed luminescence mechanism of this system was investigated by analyzing the ultraviolet absorption spectra, surface tension, fluorescence polarization, quantum yield, and the number of water molecules in the first coordination sphere of the Eu³⁺ complex.