Effect of Cyclodextrins Formulated in Liposomes and Gold and Selenium Nanoparticles on siRNA Stability in Cell Culture Medium.

Background: Encapsulation of siRNA fragments inside liposome vesicles has emerged as an effective method for delivering siRNAs in vitro and in vivo. However, the liposome's fluid-phospholipid bilayer of liposomes allows siRNA fragments to diffuse out of the liposome, decreasing the dose concentration and therefore the effectiveness of the carrier. We have previously reported that β-cyclodextrins formulated in liposomes help increase the stability of siRNAs in cell culture medium.

A Fresh Look at the Potential of Cyclodextrins for Improving the Delivery of siRNA Encapsulated in Liposome Nanocarriers.

Liposomes are among the most effective vehicles to deliver siRNAs to cells, both and . However, despite numerous efforts to improve the potential of liposomes, siRNAs begin to leach out of liposomes as soon as they are formulated. This decreases the value of liposomes for drug delivery purposes significantly, masking their true potential.

Biguanide-, imine-, and guanidine- based networks as catalysts for transesterification of vegetable oil.

Polycationic systems based on poly(hexamethylene biguanide) (PHMBG), branched polyethyleneimine (PEI) and poly(N-vinylguanidine) (PVG) have been evaluated as heterogeneous catalysts for the transesterification of sunflower oil by methanol. Insoluble networks are synthesized via crosslinking of PHMBG by either 4,4'-methylenebis(N,N-diglycidylaniline) or polyisocyanate prepolymer, PEI with sebacoyl chloride, and PVG with 1,4-butanediol diglycidyl ether. PHMBG and its crosslinked networks appeared to be remarkably efficient catalysts, enabling 80-100% triglyceride conversion within 0.

Effect of prolonged exposure to organic solvents on the active site environment of subtilisin Carlsberg.

The potential of enzyme catalysis as a tool for organic synthesis is nowadays indisputable, as is the fact that organic solvents affect an enzyme's activity, selectivity and stability. Moreover, it was recently realized that an enzyme's initial activity is substantially decreased after prolonged exposure to organic media, an effect that further hampers their potential as catalysts for organic synthesis. Regrettably, the mechanistic reasons for these effects are still debatable.

Hydrogen/deuterium exchange study of subtilisin Carlsberg during prolonged exposure to organic solvents.

It has been previously reported that prolonged exposure of an enzyme to organic solvents leads to substantial decrease of activity. This effect was found to be unrelated to the catalysts' structure or their possible aggregation in organic solvents, and up to the present day the cause for activity loss remains unclear. In the present work, the structural dynamics of the serine protease subtilisin Carlsberg (SC) have been investigated during prolonged exposure to two organic solvents by following hydrogen/deuterium (H/D) exchange of mobile protons.

Can an inactivating agent increase enzyme activity in organic solvent? Effects of 18-crown-6 on lipase activity, enantioselectivity, and conformation.

Lipase from Burkholderia cepacia (lipase BC) and lipase B from Candida antarctica (CALB) show an increase of the transesterification activity in toluene (up to 2.4- and 1.7-fold, respectively), when lyophilized with 18-crown-6.