Proceso Sol-Gel en la Síntesis de Dióxido de Silicio (Sio2)

En ciencia de los materiales el dióxido de silicio, también conocido como sílice, ha recibido significante atención en diferentes áreas de investigación, ganando un espacio importante y de mucho interés entre los investigadores, debido a sus diversas aplicaciones que abarcan desde la síntesis de soportes para catalizadores hasta materiales para la liberación controlada de fármacos. Es motivo por el cual, en este manuscrito se dan a conocer aspectos químicos fundamentales e importantes sobre el proceso sol-gel en la síntesis de la sílice a partir de moléculas precursoras de alcóxidos de silicio y organosilanos. Se analiza cómo el catalizador ácido/básico y el tipo de precursor afectan a las reacciones de hidrólisis y condensación, así como a la estructura y morfología del material. Palabra clave: Sílice, Sol-gel, Hidrólisis, Condensación, Alcóxido. Abstract In materials science, silicon dioxide has received significant attention in different research areas, gaining valuable space and interest between researchers due to its diverse applications, ranging from the synthesis of supports for catalysts to materials for controlled drug liberation. Herein we describe fundamental and important chemical aspects of the sol-gel process in the synthesis of silica, starting from precursor molecules of silicon alkoxides and organosilanes. Moreover, this review analyses how the acid/basic catalyst and the type of precursor affect the hydrolysis and condensation reaction, as well as the structure and morphology of the obtained material. Keywords: Silica, Sol-gel, Hydrolysis, Condensation, Alkoxide.

Development and Evaluation of a Reconstitutable Dry Suspension Containing Isoniazid for Flexible Pediatric Dosing

Tuberculosis (TB) is a major cause of childhood death. Despite the startling statistics, it is neglected globally as evidenced by treatment and clinical care schemes, mostly extrapolated from studies in adults. The objective of this study was to formulate and evaluate a reconstitutable dry suspension (RDS) containing isoniazid, a first-line anti-tubercular agent used in the treatment and prevention of TB infection in both children and adults. The RDS formulation was prepared by direct dispersion emulsification of an aqueous-lipid particulate interphase coupled with lyophilization and dry milling. The RDS appeared as a cream-white free-flowing powder with a semi-crystalline and microparticulate nature. Isoniazid release was characterized with an initial burst up to 5 minutes followed by a cumulative release of 67.88% ± 1.88% (pH 1.2), 60.18% ± 3.33% (pH 6.8), and 49.36% ± 2.83% (pH 7.4) over 2 h. An extended release at pH 7.4 and 100% drug liberation was achieved within 300 min. The generated release profile best fitted the zero order kinetics (R2 = 0.976). RDS was re-dispersible and remained stable in the dried and reconstituted states over 4 months and 11 days respectively, under common storage conditions.

Hypoxia- and singlet oxygen-responsive chemo-photodynamic Micelles featured with glutathione depletion and aldehyde production

Triggered drug release from anti-tumor nanomedicine is an efficient approach to address the dilemma of systemic nanocarrier stability and on-demand drug liberation in tumor sites.

Effect of microemulsion on liberation of indomethacin from hydrophilic and lipophilic gel

Effect of microemulsion on liberation of indomethacin from hydrophilic and lipophilic gelThe paper is focused on liberation of indomethacin from gels and the influence of microemulsion's presence in the system. Liberation of drug was performed in vitro through a semipermeable membrane and drug quantity was determined spectrophotometrically. Our results pointed out that the influence of microemulsion system on drug liberation depends on the gel selection. The presence of o/w microemulsion in the lipophilic gel (aerosil in liquid paraffin) increased the released amount of the drug approximately 50%. The liberation profile of indomethacin is better when the hydrophilic gel (carbopol) was used. Drug was released in higher amounts from hydrophilic gel comparised to the commercial gel. The presence of microemulsion in carbopol gel did not have any significant influence.