The Fe(3)O(4) nanoparticles, tailored with maleimidyl 3-succinimidopropionate ligands, were conjugated with paclitaxel molecules that were attached with a poly(ethylene glycol) (PEG) spacer through a phosphodiester moiety at the (C-2')-OH position. The average number of paclitaxel molecules/nanoparticles was determined as 83. These nanoparticles liberated paclitaxel molecules upon exposure to phosphodiesterase.
In an attempt to fabricate highly active immunoprobes for serum biomarker detection, we report a simple and effective method for site-specific and self-oriented immobilization of antibodies on magnetic nanoparticles (MNPs). Through boronate formation, the carbohydrate moiety within the constant domain, Fc, of the antibody can be specifically and covalently linked to a boronic acid-functionalized MNP (BA@MNP) without hindering the antigen binding domain, Fab. The performance was evaluated by immunoaffinity extraction of multiple serum antigens. Compared with the random immobilization of antibody on a MNP, the antibody self-oriented immunoprobe provides long-term stability (>2 months) and 5-fold extraction efficiency. It also provides 5-fold improved sensitivity at a low nM range (0.4 nM), presumably through enhanced antibody@MNP activity. In addition, false-positive detections arising from nonspecific binding can be completely minimized by effective surface protection using concentration-dependent dextran blocking. Compared with conventional antibody site-specific immobilization through protein G, this new BA-mediated covalent antibody immobilization provides interference-free extraction resulting from noncovalent immobilization of antibody by protein G. The new immunoassay was applied in comparative profiling of serum amyloid P (SAP), serum amyloid A (SAA), and C-reactive protein (CRP) in human serum. Our triple immunoassay revealed a distinct pattern among normal patients, patients with cancer, and patients with cardiovascular disease. Using the previously reported quantization capability of the MALDI MS readout, we expect that this site-specific immunonanoprobe-based immunoassay can be highly active, rapid, and accurate in nanodiagnosis.
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.