Design and Functional Verification of a Release-controlled Aptamer Scaffold Displayed on Graphene Surfaces for Bioseparation
Magnetic separation(MS)is frequently used to enrich specific targets from biological sam-ples,which is commonly performed using antibodies coupled immunomagnetic beads(IMBs).However,due to the high cost of antibodies and difficulties in the process of releasing captured targets,IMBs have limitations for large-scale enrichment of targeted bioproducts.The specificities and affinities of aptamers towards their targets are in line with antibodies,but with characteristic of significantly lower costs of prep-aration,simpler structures,and higher chemical stability.In this study,taking advantages of the distinct adsorption features of graphene for single-stranded and double-stranded nucleic acids,we designed a novo system as bioseparation method that could display aptamers on graphene surfaces to enrich targets and then manipulate their release.This system mainly includes two units.Take CD63 aptamer as an exam-ple:double-stranded oligonucleotides scaffold attached to the graphene surface for CD63 aptamer exhibi-tion;and a single-stranded oligonucleotide complementary to the scaffold bipod sequence to desorb the captured targets from graphene.In this study,firstly,using graphene oxide(GO)paper as a graphene surface,we fluorescently labeled scaffolds or CD63 proteins and compared the fluorescence intensity difference on the GO paper before and after scaffold or CD63 protein release.Subsequently,a novo mate-rial,amino-modified graphene-shelled iron-nitrogen magnetic beads were introduced to carry the scaffold,and used to capture CD63 proteins from cell lysates.The results indicate that this scaffold can display the aptamer on the graphene surface for CD63 protein capture and controlled release.Using selected modified graphene magnetic beads carried with the scaffold,we achieved the capture of CD63 proteins from cell ly-sates.This system is expected to enrich various proteins such as CD63,or capture exosomes by hooking membrane proteins.
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