Functionalized poly(butylene succinate) (PBS) samples were prepared by a post-polymerization method
based on the coupling reaction between TEMPO derivatives bearing different functionalities and
PBS macroradicals generated by H-abstraction using a peroxide. 4-Benzoyloxy-2,2,6,6-
tetramethylpiperidine-1-oxyl (BzO-TEMPO) and 4-(1-naphthoate)-2,2,6,6-tetramethylpiperidine-1-oxyl
(NfO-TEMPO), a pro-fluorescent nitroxide, were successfully grafted on PBS, as revealed by MALDI TOF
MS and UV-Vis spectroscopy. The functionalization degrees were accurately determined by UV-Vis
analysis and confirmed by 1H-NMR spectroscopy. The grafting site was identified by combining
theoretical calculations with experimental evidence. This evidence was collected by both EPR analysis of
a functionalized sample subjected to controlled heating in the EPR cavity, and by 1H-NMR spectroscopy.
Our functionalization method, which was also tested for poly(lactic acid) (PLA), preserves the original
polymer structure. This avoids the crosslinking-branching side reaction, which generally affects the free
radical treatment of biodegradable aliphatic polyesters. In addition, using a pro-fluorescent nitroxide to
form functionalized samples is a significant step towards unambiguously demonstrating the radical
grafting on these types of polymer. It also proves that well-defined fluorescently labeled biodegradable
polyesters can be tailored
Detection
of circulating tumor cells (CTCs) may be applied for
diagnosis of early tumors like a liquid biopsy. However, the sensitivity
remains a challenge because CTCs are extremely rare in peripheral
blood. In this study, we developed a supersensitive CTC analysis system
based on triangular silver nanoprisms (AgNPR) and superparamagnetic
iron oxide nanoparticles (SPION) with function of capture, enrichment,
detection, and release. The AgNPR was encoded with MBA (i.e., 4-mercaptobenzoic
acid) and modified with rBSA (i.e., reductive bovine serum albumin)
and FA (i.e., folic acid) generating organic/inorganic composite nanoparticle
MBA-AgNPR-rBSA-FA, which has the function of surface-enhanced Raman
scattering (SERS). The optimized SERS nanoparticles (i.e., MBA3-AgNPR-rBSA4-FA2)
can be utilized for CTC detection in blood samples with high sensitivity
and specificity, and the LOD (i.e., limit of detection) reaches to
five cells per milliliter. In addition, the SPION was also modified
with rBSA and FA generating magnetic nanoparticle SPION-rBSA-FA. Our
supersensitive CTC analysis system is composed of MBA3-AgNPR-rBSA4-FA2
and SPION-rBSA-FA nanoparticles, which were applied for capture (via
interaction between FA and FRα), enrichment (via magnet), and
detection (via SERS) of cancer cells from blood samples. The results
demonstrate that our supersensitive CTC analysis system has a better
sensitivity and specificity than the SERS nanoparticles alone, and
the LOD is up to 1 cell/mL. The flow cytometry and LSCM (i.e., laser
scanning confocal microscope) results indicate the CTCs captured,
enriched, and isolated by our supersensitive CTC analysis system can
also be further released (via adding excessive free FA) for further
cell expansion and phenotype identification.
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