Gold nanoparticle-based colorimetric biosensors

Gold nanoparticles (AuNPs) provide excellent platforms for the development of colorimetric biosensors as they can be easily functionalised, displaying different colours depending on their size, shape and state of aggregation. In the last decade, a variety of biosensors have been developed to exploit the extent of colour changes as nano-particles (NPs) either aggregate or disperse, in the presence of analytes. Of critical importance to the design of these methods is that the behaviour of the systems has to be reproducible and predictable. Much has been accomplished in understanding the interactions between a variety of substrates and AuNPs, and how these interactions can be harnessed as colorimetric reporters in biosensors. However, despite these developments, only a few biosensors have been used in practice for the detection of analytes in biological samples. The transition from proof of concept to market biosensors requires extensive long-term reliability and shelf life testing, and modification of protocols and design features to make them safe and easy to use by the population at large. Developments in the next decade will see the adoption of user friendly biosensors for point-of-care and medical diagnosis as innovations are brought to improve the analytical performances and usability of the current designs. This review discusses the mechanisms, strategies, recent advances and perspectives for the use of AuNPs as colorimetric biosensors. Keywords: biosensors, colloids, gold nanoparticles, nanotechnology, surface plasmon resonance, enzymes, quantification

Nanoparticules originales à base de carboxylates de fer (encapsulation du busulfan, de l'AZT-TP et du cidofovir)

Cette thèse a comme but de préparer de nanoparticules de (MOF) ou plus précisément de carboxylates de fer présentant des taille compatibles avec une administration intraveineuse, porosités importante, une bonne biocompatibilité et des capacités d encapsulation et de libération de principes actifs d intérêt comme le busulfan (agent anticancéreux), l AZT-TP et le cidofovir (agents antirétroviraux). Dans la perspective des applications biomédicales, nous avons choisi la famille des carboxylates de fer pour préparer nos nanoparticules, car ces matériaux peuvent être élaborés à partir de fer et des acides di(ou tri) carboxyliques de très faible DL50.This thesis is intended to prepare nanoparticles (MOF) or more precisely iron carboxylates having a size compatible with intravenous, high porosity, good biocompatibility and capability of encapsulation and release of active ingredients of interest as busulfan (anticancer agent), AZT-TP and cidofovir (antiretrovirals). From the perspective of biomedical applications, we chose the family of iron carboxylates to prepare our nanoparticles, because these materials can be made from iron and acid di (or tri) carboxylic very low LD50.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Selective spectrofluorimetric method for the determination of perindopril erbumine in bulk and tablets through derivatization with dansyl chloride

Background: Perindopril erbumine is an antihypertensive, which belongs to the category of angiotensin-converting enzyme inhibitors (ACE inhibitors) that inhibit the conversion of angiotensin I to angiotensin II. Methods: A new, selective, and sensitive spectrofluorimetric method was developed for the determination of perindopril erbumine based on the reaction with dansyl chloride in alkaline medium to give a highly fluorescent derivative which was measured at 496 nm after excitation at 340 nm in dichloromethane. The reaction conditions were studied and optimized. Results: Under the optimum conditions, the fluorescence intensity was linear over a concentration range of 1.0 to 21.0 μg/mL (R2 = 0.9997) with a detection limit of 0.242 μg/mL. In order to validate the method, the results were compared with those obtained by a high performance liquid chromatography method. Conclusions: The proposed method was successfully applied to the analysis of perindopril erbumine in pure form and tablets with good precision and accuracy as revealed by t- and F tests. The mechanism of the reaction has also been discussed

Vitiligo: Types and Treatment According to the Most Renowned Arab Muslim Scientists

Introduction: Vitiligo is one of the oldest diseases that have afflicted people. It was firstly described be old Egyptians in Ebres' Papyrus more than four thousand years ago. In this presentation, focus will be on the contribution of Muslim Arab scientists to the field of Vitiligo. Aims: The purpose of this research is to shed light on an important aspect in Islamic Arabic heritage in relation to dermatology, as regards old Muslim Arab physicians. It has been found out that Abi Al-HasanAl-Tabari (375 H.-985 A.D.), a physician of the fourth hegira century, tackled several medical issues in his book, Hippocrates Treatments, among them is Vitiligo. Vitiligo was also mentioned in Al-Razi's, IbnSina's and Al-Zahrawi's books. Because of this, we have chosen to study this disease as its has been the concern of old and contemporary physicians' treatments. Methodology of research: The research type followed in this study is the historical retrieval, through going back to old medical books especially Abi Al-Hasan Al Tabari's Hippocrates Treatments, especially the seventh article which consists of sixty chapters, of which the tenth chapter is dedicated to talk about Vitligo. Other Arabic medical books that handled Vitiligo was Al-Razi's Mansouriin Medicine (375 H.-985 A.D.) and Al-Zahrawi's Managing (404 H.). Results: 1- Muslims Arab scientists differentiated between Vitiligo and leprosy. 2- Al-Zahrawi classified Vitiligo into three types. 3- Abi Al-Hasan Al-Tabari specified a complete chapter to talk about Vitiligo and its treatments. Conclusion: Vitiligo has been known since oldest times. In this respect, Muslim scientists contributed to the field of Vitiligo with respect to diagnosing this disease relying on strong observation and the disease distinguishing features. However, up till now it has not been often found any effective medication for such a disease

NEW FLUORESCENCE QUENCHING BASED METHOD FOR THE DETERMINATION OF TRANDOLAPRIL IN BULK AND CAPSULES

Objective: The objective of the method was to develop a new, simple, rapid and accurate spectrofluorimetric method for the determination of trandolapril in bulk and capsules. Methods: Trandolapril reacts with fluorescein to form a charge transfer complex which results in fluorescence quenching of the fluorescein dye. The fluorescence quenching intensity was measured at 515 nm after excitation at 470 nm. Results: Under the optimum conditions, the quenched fluorescence intensity was linear with the concentration of trandolapril in the range of 1.80 –9.60 μg/mL (4.18×10−6 – 22.30×10−6 M) (R2= 0.9983) with a detection limit of 0.345 μg/mL. In order to validate the method the results were compared with those obtained by a high performance liquid chromatography method. The proposed method was successfully applied to the analysis of trandolapril in pure form and capsules with good precision and accuracy compared to the reported method as revealed by t- and F- tests. Conclusion: The developed method was simple, fast, accurate and precise. It could be applied for routine quality control analysis of trandolapril in its pure form and in capsules

Optimisation of the synthesis of MOF nanoparticles made of flexible porous iron fumarate MIL-88A

The synthesis of nanoparticles of the porous flexible iron fumarate MIL-88A (MIL stands for Materials from Institut Lavoisier) has been studied through the use of several synthetic routes using non-toxic solvents. Hydro-solvothermal synthesis under dynamic or static, ambient or autogenous pressure conditions, assisted or not by microwave irradiation or ultrasonic methods have been compared in terms of particle size, polydispersity and yield. Different parameters such as temperature, time, concentration, pH or the use of additives (base, inhibitor) were evaluated. The resulting nanoparticles were characterised using X-ray powder diffraction (XRPD), dynamic light scattering (DLS), transmission and scanning electron microscopy (TEM and SEM) and the yield of the reaction was estimated. Although significant amounts of small nanoparticles (�200 nm) were obtained from each synthetic route, most conditions led to an important polydispersity. Ultrasonic synthesis led, on the contrary, to very low yields of small and monodisperse nanoparticles. Finally, only microwave assisted hydrothermal synthesis afforded the successful fast synthesis of high yields of small (<100 nm) and monodispersed nanoparticles

Porous metal organic framework nanoparticles to address the challenges related to busulfan encapsulation

Busulfan is an alkylating agent widely used in chemotherapy, but with severe side effects. Many attempts have been made to entrap busulfan in nanocarriers to avoid liver accumulation and to protect it against rapid degradation in aqueous media. However, poor loadings ( =5 wt%) and fast release were generally obtained due to the low affinity of busulfan towards the nanocarriers. Moreover, drug crystallization often occurred during nanoparticle preparation. To circumvent these drawbacks, metal organic framework (MOF) nanoparticles, based on crystalline porous iron (III) carboxylates, have shown an unprecedented loading (up to 25 wt%) of busulfan. This was attributed to the high porosity of nanoMOFs as well as to their hydrophilic–hydrophobic internal microenvironment well adapted to the amphiphilic character of busulfan. NanoMOFs formulations have kept busulfan in molecular form, preventing its crystallization and degradation. Indeed, busulfan was released intact, as proved by the maintenance of its pharmacological activity

Towards an Improved anti-HIV Activity of NRTI via Metal-Organic Frameworks Nanoparticles

Nanoscale mesoporous iron carboxylates metal-organic frameworks (nanoMOFs) have recently emerged as promising platforms for drug delivery, showing biodegradability, biocompatibility and important loading capability of challenging highly water-soluble drugs such as azidothymidine tryphosphate (AZT-TP). In this study, nanoMOFs made of iron trimesate (MIL-100) were able to act as efficient molecular sponges, quickly adsorbing up to 24 wt% AZT-TP with entrapment efficiencies close to 100%, without perturbation of the supramolecular crystalline organization. These data are in agreement with molecular modelling predictions, indicating maximal loadings of 33 wt% and preferential location of the drug in the large cages. Spectrophotometry, isothermal titration calorimetry, and solid state NMR investigations enable to gain insight on the mechanism of interaction of AZT and AZT-TP with the nanoMOFs, pointing out the crucial role of phosphates strongly coordinating with the unsaturated iron(III) sites. Finally, contrarily to the free AZT-TP, the loaded nanoparticles efficiently penetrate and release their cargo of active triphosphorylated AZT inside major HIV target cells, efficiently protecting against HIV infection

Porous metal–organic-framework nanoscale carriers as a potential platform for drug delivery and imaging

In the domain of health, one important challenge is the efficient delivery of drugs in the body using non-toxic nanocarriers. Most of the existing carrier materials show poor drug loading (usually less than 5 wt% of the transported drug versus the carrier material) and/or rapid release of the proportion of the drug that is simply adsorbed (or anchored) at the external surface of the nanocarrier. In this context, porous hybrid solids, with the ability to tune their structures and porosities for better drug interactions and high loadings, are well suited to serve as nanocarriers for delivery and imaging applications. Here we show that specific non-toxic porous iron(III)-based metal–organic frameworks with engineered cores and surfaces, aswell as imaging properties, function as superior nanocarriers for efficient controlled delivery of challenging antitumoural and retroviral drugs (that is, busulfan, azidothymidine triphosphate, doxorubicin or cidofovir) against cancer and AIDS. In addition to their high loadings, they also potentially associate therapeutics and diagnostics, thus opening the way for theranostics, or personalized patient treatments