Synthesis And Characterization Of Mannosylerythritol Lipids-Based Nanomaterials,and Their Potential Applications

The utilization of biosurfactants(BSs)in the synthesis of nanomaterials has been emerged as an alternative green material compared to the physiochemical methods,BSs are biodegradable,stable,less toxic,uniform in shape,and have improved their biomedical activities of nanomaterials.Among them,mannosylerythritol lipids(MEL)are surface-active molecules that affiliated to the glycolipid group of BSs and produced by different microorganisms.MEL has gained particular attention due to its various potential bioactivities,such as antimicrobial activity,antioxidant,interfacial,and antitumor properties.In this study,we produced MEL from Ustilago maydis CGMCC 5.203 by resting cell fermentation under the limited nitrogen using different carbon sources,including olive,sunflower,and soybean oil.The obtained MEL was exploited to mediate a variety of nanomaterials,namely,MEL-AuNPs,MEL@AgNPs,MEL@ZnONPs,and Ag-ZnO/MEL/GA nanocomposites were biosynthesized using MEL and gum arabic.Further,the immobilization of lysozyme into the Ag@LZ/CS-MBs complex was fabricated using chitosan/silver microbeads by adding different amounts of MEL.Moreover,the biosynthesized nanomaterials were verified using UV-visible spectrum,X-ray diffraction,FE-SEM,TEM,EDX,and FTIR spectroscopy.Also,the biological activities,such as antibacterial,antidiabetic,anticancer,and antioxidant activities were investigated.Our findings indicated that MEL plays a crucial role in the rapid bio-fabrication of metallic nanoparticles.Besides,the Ag-ZnO/MEL/GA nanocomposites exhibited great potential to serve as antitumor against HepG2,antidiabetic,and antibacterial.Furthermore,the Ag@LZ/CS-MBs complex showed a potent antibacterial efficacy and high biocompatibility,which could be useful for food and medical applications.The main findings are summarized as follows:a)The production of MEL from different carbon sources by the resting cells of Ustilago maydis 203 under growth-limiting nitrogen conditions.After fermentation,extracted and purified by silica-gel column chromatography,then it was confirmed by using thin-layer chromatography(TLC).The total yields of MEL from sunflower,olive,and soybean oil were 10.36,5.26,and 7.03 g/L,respectively.b)The fabrication of MEL-AuNPs was verified using UV-visible spectrum,XRD,TEM,FTIR,SEM,and EDX.In the biomedical examinations,MEL-AuNPs demonstrated potential cytotoxicity against HepG2 cells,and IC50 values were found to be 100 and 75?g/mL for 24 h and 48 h of exposure,respectively,which indicates its excellent performance against cancer cells.The IC50 value of MEL-AuNPs was found to be 115 and 124 ?g/mL for DPPH and ABTS scavenging activities,respectively.The biosynthesized MEL-AuNPs significantly inhibited cell growth of pathogenic bacteria.c)The biosynthesized nanocomposites were examined using XRD,TEM,SEM,and FTIR spectroscopy.The Ag-ZnO/MEL/GA nanocomposites showed greater antidiabetic activity against ?-amylase and ?-glucosidase,and higher antibacterial activity compared to MEL@AgNPs and MEL@ZnONPs.Furthermore,HepG2 cells were exposed to MEL@AgNPs,MEL@ZnONPs,and Ag-ZnO/MEL/GA nanocomposites for 24 h and their IC50 values were 63.25,26.91 and 28.97 ?g mL-1(P<0.05),respectively.d)The X-ray diffraction analyses of Ag@LZ/CS-MBs demonstrated weak peaks after crosslinking with genipin.FE-SEM images and FTIR spectra indicated the successful fabrication of Ag@LZ/CS-MBs.The enzymatic activity of LZ increased at low concentrations(<15 mg)of MEL.The prepared samples were highly effective in inhibiting VREF growth in the first 30 min of incubation.For all incubation periods,the Ag@LZCS-MBs displayed higher antibacterial efficacy compared to the free lysozyme samples.The human colon cells showed a minor reduction in cell viability when being exposed to Ag@LZ/CS-MBs complex for 6 h,and 24 h without affecting the morphology.