Wrapping of gold nanoparticles (AuNPs) with a biocompatible
matrix,
to gain AuNP colloids, is a general strategy to synthesize the AuNPs
for biomedical purposes. This work reports the synthesis of AuNP colloids
in the aqueous solution of several natural matrices using a liquid-phase
plasma process. Two classes of natural substances used are sugars
(including: glucose, fructose, and sucrose) and biopolymers (including:
carboxymethyl cellulose, sodium alginate, and gelatin). All are negatively
charged water-soluble substances that are claimed to be sources of
energy for cells to grow and have a high potential to be compatible
with them. The study has emerged since one question arises: “Do these matrices also promote the growth of cancer cells?” The synthesis is performed by generating plasma across
a pair of electrodes immersed in an aqueous solution of a natural
matrix containing a gold precursor (HAuCl4·3H2O). Two concentrations of the matrices (0.5 and 1.0% w/v)
are used, and the plasma treatment times are varied (0, 10, and 30
min). The effect of the type and concentration of natural matrices
as well as the plasma treatment time on the formation of AuNPs, along
with their physical and chemical properties, including morphology,
size, hydrodynamic diameter (d
h), colloidal
stability, and charge on the AuNP surface, is evaluated. We find that
the charge of the AuNP surfaces could be altered by the plasma treatment.
Eventually, cytotoxicity test results against normal (MRC-5) and cancer
(H460 and HeLa) cell lines could not only answer our opening question
but also suggest a rather complex response. Our findings indicate
the great potential of the obtained AuNP colloids as a part of cancer
therapy.
Background: Aldehyde-deformylating oxygenase (ADO) is a non-heme di-iron enzyme that catalyzes deformylation of aldehydes to generate alkanes/alkenes. In this study, we report for the first time that under anaerobic or limited oxygen conditions, Prochlorococcus marinus (PmADO) can generate full-length fatty alcohols from fatty aldehydes without eliminating a carbon unit. Results: Unlike the native activity of ADO which requires electrons from the Fd/FNR electron transfer complex, the aldehyde reduction activity of ADO requires only NADPH. Our results demonstrated that yield of alcohol products can be affected by oxygen concentration and type of aldehyde. Under O2-scant conditions (10-15%), yields of octanol and dodecanol were around 40-60% and could be increased up to 80% under strict anaerobic conditions (>0.0004%). Unexpectedly, Fe2+ cofactor is not involved in the aldehyde reductase activity of PmADO because yields of alcohols obtained from holo- and apo-enzymes were similar under anaerobic conditions. The direct hydride transfer activity of PmADO is highly specific to substrates; NADPH not NADH can be used as a reductant to reduce medium-chain fatty aldehydes (C6-C10) with decanal as the most preferred substrate (the highest kcat/Km value with 98% bioconversion yield). Molecular dynamics (MD) simulations was used to identify a binding site of NADPH which is located close to the aldehyde binding site. In the metabolic engineered cells containing PmADO, dual activities of alkane and alcohol production could be detected. Conclusion: The findings reported herein highlight a new activity of PmADO which may be applied as a biocatalyst for industrial synthesis of fatty alcohols in the future.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.