Surface activity as basis for pharmaceutical applications of hydrocolloids: A review.

Hydrocolloids are polymeric substances with mild to moderate surface activity. They are widely used as excipients in drug delivery systems where they serve various purposes such as suspending, emulsifying, wetting, foaming, solubilizing, stabilizing and bioadhesive agents as well as permeation enhancers. The surface activity and pharmaceutical applications of some hydrocolloids were reviewed in this study. The review showed that most natural hydrocolloids are characterized by higher critical micelle concentrations (CMC) compared to semisynthetic and synthetic ones. Cashew and khaya gums (exudates gums) with hydrophile – lipophile balance (HLB) values in the range of 15 - 18 possess solubilizing property. Dispersions of afzelia and prosopis gums (seed gums) have higher viscosity compared to acacia gum and may produce more stable disperse systems. Semisynthetic and synthetic hydrocolloids like sodium carboxyl methylcellulose and polyvinylpyrrolidone are characterized by low CMC and exhibit very high surface elasticity at concentrations above CMC thus exhibiting high bioadhesive strength. Therefore, surface activity is the basis for most pharmaceutical applications of hydrocolloids and the application of individual hydrocolloid depends on its adsorption power, CMC, HLB value and bioadhesive strength.

Dendritic surface functionalization of nanomaterials: controlling properties and functions for biomedical applications

A wide variety of nanomaterials have demonstrated promise in medical applications such as drug delivery and imaging. In these applications, the surface chemistry of the materials is critical as it plays an important role in determining the toxicity and biodistribution behavior of the material. We review here the functionalization of nanomaterials with dendrons as an efficient method to alter the surface chemistry of the materials, introducing new properties and functions. Described here is the functionalization of superparamagnetic iron oxide nanoparticles (SPIO) with dendritic guanidines to enhance their transport into cells for magnetic resonance imaging applications. The introduction of dendrons bearing peripheral hydroxyls, amines, guanidines, carbohydrates and Gd(III) chelates to polymer vesicles (polymersomes) is also described. These dendritic moieties allow for modulation of toxicity, cell uptake, protein binding, and contrast agent efficiency, while at the same time allowing the stabilities of the polymersomes to be maintained. Thus, this approach holds promise for the development of a wide range of multifunctional materials for pharmaceutical applications.

Uma grande variedade de nanomateriais tem demonstrado aplicações médicas promissoras, tais como liberação de fármacos e em imagens. Nestas aplicações, a superfície química dos materiais é crítica, uma vez que exerce papel importante na determinação da toxicidade e comportamento de biodistribuição do material. Aqui, nós revisamos a funcionalização de nanomateriais, como dendrons, como método eficiente de alterar a superfície química destes compostos, introduzindo novas propriedades e funções. Descritos aqui estão nanopartículas superparamagnéticas de óxido de ferro (do inglês, SPIO), com guanidinas dendríticas para aumentar seu transporte para o interior das células, úteis em imagens de ressonância magnética. A introdução de dendrons contendo hidroxilas, aminas, guanidinas, carboidratos e quelatos de Gd(III) periféricos em vesículas poliméricas (polymersomes) também está descrita. Esses grupos dendríticos permitem a modulação de toxicidade, captura celular, ligação à proteína e eficiência como agente de contraste, enquanto que, ao mesmo tempo, permitem a manutenção da estabilidade das vesículas poliméricas. Assim, essa abordagem é promissora para o desenvolvimento de grande variedade de materiais multifuncionais para aplicações farmacêuticas.

Óleo essencial de Thymus vulgaris sobre o crescimentode Streptococcus mutans / Effect of the Thymus vulgaris essential oil on the growth of Streptococcus mutans

The traditional Mediterranean herb thyme (Thymus vulgaris) is a source of an essential oil that has been shown to possess antimicrobial activity against many microorganisms. A considerable part of the general population has dental caries and Streptococcus mutans is one of the microorganisms responsible. The aim of this study was to assess the effect of the essential oil extracted from thyme on the growth of S. mutans, the main bacterium involved in the etiology of dental caries, as well as to incorporate this oil into a toothpaste formulation for preliminary assessment. The broth dilution technique was used in threefold tests for antibacterial activity. The concentrations tested were 1%, 5% and 10% essential oil diluted in ethanol or mineral oil. The controls were triclosan at 0.25% and 0.5%, chlorhexidine digluconate at 0.06% and 0.12%, and ethanol. The 1% solution of thyme essential oil in ethanol proved to be the most efficient against Streptococcus mutans and may be considered viable as an ingredient of toothpaste, both with regard to cost and to the sensory profile of the product. Also, analyses of the characteristics of the formulation indicated that the product is stable.

Thymus vulgaris (tomilho) é uma fonte de óleo essencial que tem demonstrado atividade antimicrobiana. Uma parcela considerável da população tem apresentado problemas dentários, tais como a cárie, na qual o Streptococcus mutans é um microrganismo de fundamental importância. O objetivo deste trabalho foi avaliar o efeito do óleo essencial de tomilho sobre o crescimento do Streptococcus mutans, a principal bactéria relacionada com a etiologia da cárie dentária, bem como veicular este óleo essencial em uma formulação de creme dental para estudo preliminar. O método empregado foi diluição em caldo. As concentrações utilizadas de óleo essencial foram 1%, 5% e 10% de óleo essencial diluído em etanol ou óleo mineral. Os controles foram triclosan a 0,25% e 0,5%, bem como digluconato de clorexidina a 0,06% e 0,12%. A amostra contendo 1% de óleo essencial de tomilho diluída em etanol foi a mais eficaz, sendo efetiva contra Streptococcus mutans e, portanto considerada viável em relação ao custo e ao sensorial conferido ao produto, sendo que a formulação avaliada foi considerada estável.