Green Chemistry and Biosurfactant Research - Biosurfactants: Research Trends and Applications - page 19

In another work, a liposome vector containing betasitosterol beta-d-glucoside
BS-complexed DNA was successfully used for herpes simplex virus thymidine
kinase gene therapy (Maitani et al., 2006). More recently, nanovectors contain-
ing a BS have been successfully used to increase the efficacy for gene transfection
in vitro and in vivo (Nakanishi et al., 2009). On the other hand, Morita et al. (2009),
using a three-dimensional cultured human skin model, observed that the viability
of the SDS damaged cells was markedly improved by the addition of MEL-A in a
dose-dependent manner. This demonstrated that MEL-A had a ceramide-like mois-
turizing activity toward the skin cells. Another interesting application for natural
surfactant is the possibility to synthesize metal-bound nanoparticles using an envi-
ronmentally friendly and benign technology (Palanisamy and Raichur, 2009). The
use of gold nanoparticles, in particular, is currently undergoing a dramatic expansion
in the field of drug and gene delivery, targeted therapy, and imaging (Boisselier and
Astruc, 2009). Recently, Reddy et al. (2009) synthesized, for the first time, surfactin-
mediated gold nanoparticles, opening the way to a new and fascinating application
of BSs in the biomedical field.
f lavoliPiDs : n ovel B iosurfaCtants
Bodour et al. (2004) reported that the genus Flavobacterium produces a BS.
Flavobacterium is an aerobic, nonfermenting, gram-negative, rod-shaped micro-
organism that exhibits gliding motility. It belongs to the Flavobacteriaceae family
in the Cytophaga-Flavobacterium-Bacteroides phylum. The small-subunit rRNA
of Flavobacterium suggests that it is closely related to the sulfur bacteria (Woese
et al., 1990; Gherna and Woese, 1992). This organism is ubiquitous in the envi-
ronment. Flavobacterium is known to produce pigments ranging in color from
yellow to orange, pink, red, and brown. Some species of Flavobacterium degrade
organic contaminants, such as pentachlorophenol, nylon oligomers, polyaromatics,
and pesticides.
Flavolipid as an emulsifier. : The flavolipid is a strong and stable emulsifier. Flavolipid
concentrations as low as 19 mg/L exhibited an emulsification index of 100%, indicat-
ing complete emulsification of the oil layer. Emulsions were stable even after 1 week.
Remediation applications : BSs have been intensively studied for application in
the remediation of organic chemical- and metal-contaminated sites. Therefore,
the flavolipid was subjected to a series of tests to begin evaluation of its ability
to enhance solubilization and biodegradation of hydrocarbons and to determine
whether it has the ability to complex metals. Success has already been achieved in
the following cases:
1. Solubilization and biodegradation of hexadecane
2. Effect of BS on complex formation with heavy metals
The flavolipids described herein represent a new class of BSs with strong surface
activity and emulsifying ability. The polar moiety of flavolipid features citric acid