The performance of surfactant mixtures at low temperatures

Optimising detergency at lower temperatures is of increasing interest due to environmental and economic factors, and requires a greater understanding of the effects of temperature on the adsorption of surfactant mixtures at interfaces. The adsorption properties of surfactant mixtures and biosurfactant/surfactant mixtures have been studied at room temperatures and at temperatures below ambient using surface tension and neutron reflectivity measurements. For the ternary surfactant mixture of octaethylene monododecyl ether, C12E8, sodium dodecyl 6-benzene sulfonate, LAS, and sodium dioxyethylene glycol monododecyl sulfate, SLES, the surface tension at the air-water interface increases with decreasing temperature. In contrast, there is a notable reduction in the increase in the surface tension with a decrease in temperature from 25 °C to 10 °C for the 5 component rhamnolipid/surfactant mixture of the mono-rhamnose, R1, and di-rhamnose, R2, with C12E8/LAS/SLES. The associated neutron reflectivity data for the ternary C12E8/LAS/SLES mixture and the significant observation is that the 3, 4, and 5-component mixtures containing rhamnolipids in conjunction with the other surfactants show changes in composition and adsorbed amounts of the individual components which are close to the experimental error. However the significant observation is that the neutron reflectivity data indicate that the improved surface tension tolerance at lower temperatures is associated with the dominance of the rhamnolipid adsorption in such mixtures. Hence the introduction of the rhamnolipids provides a tolerance to the adverse effects associated with reduced temperatures, and a potential for improved detergency at relatively low temperatures

Biomedical and therapeutic applications of biosurfactants

During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases and as therapeutic agents due to their antibacterial, antifungal and antiviral activities. Furthermore, their role as anti-adhesive agents against several pathogens illustrate their utility as suitable anti-adhesive coating agents for medical insertional materials leading to a reduction of a large number of hospital infections without the use of synthetic drugs and chemicals. Biomedical and therapeutic perspectives of biosurfactants applications are presented and discussed in this chapter

Thermally enhanced approaches for bioremediation of hydrocarbon contaminated soils

process significantly. In this study we investigated the benefits of high temperature in enhancing hydrocarbon degradation rates and evaluated the effect of different biostimulants. Hexadecane polluted soil microcosms with various amendments were incubated both at 60 C and room temperature (18 C) and analyzed periodically up to 40 d for the degradation of hydrocarbon and the response of the microbial population. Natural attenuation showed a satisfactory intrinsic degradative capability at 60 C and the addition of inorganic N, P and K increased the degradation rates by 10%. The addition of rhamnolipid biosurfactant further enhanced the bioavailability of alkane to microbial degradation resulting in up to 71% removal at 60 C and 42% at 18 C. Significant input to hexadecane degradation occurred at 60 C (70%) as a result of the bioaugmentation with thermophilic Geobacillus thermoleovorans T80, which did not take place at 18 C. Coupling high temperature to all amendments resulted in 90% removal of the hexadecane from soil after 40 d which was also accompanied with an increase in bacterial numbers. The results suggest that thermally enhanced bioremediation may be an efficient technology for the treatment of hydrocarbon-contaminated soils

Carrier�Based Systems as Strategies for Oral Delivery of Therapeutic Peptides and Proteins: A Mini�Review

Peptides and proteins play an essential role in biological systems and the human body. Deficiency or dysfunction of peptides and proteins such as insulin can lead to various illnesses. The therapeutic use of peptides and proteins in some illnesses such as diabetes, cardiovascular disease, autoimmunity, and cancer, among others, is highly considered. Peptides and proteins have large molecular structures and are generally hydrophilic, and maintaining their spatial composition or tertiary configurations are necessary for their pharmacological activities. Maintaining the stability of the protein structure and composition is therefore very important and necessary to maintain functionality. There are different routes for peptides and proteins administration such as injection (subcutaneous, intravenous, and intramuscular), oral, nasal, pulmonary, rectal, and ocular routes. The oral administration route is better accepted by the patient due to safety and ease of use. However, oral administration often is unsuitable because of the physicochemical properties and macromolecular structure of proteins and the presence of gastrointestinal (GI) enzymes under an acidic environment within the stomach. Proteins and peptides undergo enzymatic degradation, tertiary structural alteration, and low absorption. This necessitates the need to use alternative oral drug delivery systems for peptides and proteins that maintain their overall structure and enhances their absorption and bioavailability. In this article, we review carrier-based oral drug delivery systems that were suitable for peptides and proteins. © 2021, The Author(s), under exclusive licence to Springer Nature B.V