RESUMEN
Surfactants are amphiphilic compounds having hydrophilic and hydrophobic moieties in their structure. They can be of synthetic or of microbial origin, obtained respectively from chemical synthesis or from microorganisms' activity. A new generation of ecofriendly surfactant molecules or biobased surfactants is increasingly growing, attributed to their versatility of applications. Surfactants can be used as drug delivery systems for a range of molecules given their capacity to create micelles which can promote the encapsulation of bioactives of pharmaceutical interest; besides, these assemblies can also show antimicrobial properties. The advantages of biosurfactants include their high biodegradability profile, low risk of toxicity, production from renewable sources, functionality under extreme pH and temperature conditions, and long-term physicochemical stability. The application potential of these types of polymers is related to their properties enabling them to be processed by emulsification, separation, solubilization, surface (interfacial) tension, and adsorption for the production of a range of drug delivery systems. Biosurfactants have been employed as a drug delivery system to improve the bioavailability of a good number of drugs that exhibit low aqueous solubility. The great potential of these molecules is related to their auto assembly and emulsification capacity. Biosurfactants produced from bacteria are of particular interest due to their antibacterial, antifungal, and antiviral properties with therapeutic and biomedical potential. In this review, we discuss recent advances and perspectives of biosurfactants with antimicrobial properties and how they can be used as structures to develop semisolid hydrogels for drug delivery, in environmental bioremediation, in biotechnology for the reduction of production costs and also their ecotoxicological impact as pesticide alternative.
RESUMEN
Silica gel containing silver ions was prepared and characterized. Silica was organofunctionalized with 3-mercaptopropyl group by using grafting reaction followed by silver ions adsorption (silver covalently bonded to mercaptopropyl silca gel, Ag-MPSG). The organofunctionalization and silver coordination were observed by transmission infrared spectroscopy and elemental analyses (CHN and EDS). The textural characteristics were studied by N2 adsorption-desorption isotherms. Additionally, optical properties were studied by diffuse reflectance spectroscopy. The Ag-MPSG material was employed as stationary phase for the first time for fractionation of a heavy gas oil sample resulting in a fraction that is richer in polycyclic aromatic sulfur heterocycles (PASH). The fractions were analyzed by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detector and Ag-MPSG material provided similar fractionation performance when compared to conventional material [palladium covalently bonded to mercaptopropyl silca gel, Pd(II)-MPSG] usually employed for the same purpose and as the cost of silver is less than the one of palladium, the cost of the fractionation phase was reduced.