Antibodies have been widely used to provide targeting ability and to enhance bioactivity owing to their high specificity, availability, and diversity. Recent advances in biotechnology and nanotechnology permit site-specific engineering of antibodies and their conjugation to the surfaces of nanoparticles (NPs) in various orientations through chemical conjugations and physical adhesions. This study proposes the conjugation of poly(lactic-co-glycolic acid) (PLGA) NPs with antibodies by using two distinct methods, followed by a comparison between the cell-targeting efficiencies of both techniques. Full-length antibodies were conjugated to the PLGA-poly(ethylene glycol)-carboxylic acid (PLGA-PEG-COOH) NPs through the conventional carbodiimide coupling reaction, and f(ab′)2 antibody fragments were conjugated to the PLGA-poly(ethylene glycol)-maleimide(PLGA-PEG-Mal) NPs through interactions between the f(ab′)2 fragment thiol groups and the maleimide located on the nanoparticle surface. The results demonstrate that the PLGA nanoparticles conjugated with the f(ab′)2 antibody fragments had a higher targeting efficiency in vitro and in vivo than that of the PLGA nanoparticles conjugated with the full-length antibodies. The results of this study can be built upon to design a delivery technique for drugs through biocompatible nanoparticles.
Deoxyribonuclease‐I (DNase‐I), a representative endonuclease, is an important biomarker for the diagnosis of infectious diseases and cancer progression. However, enzymatic activity decreases rapidly ex vivo, which highlights the need for precise on‐site detection of DNase‐I. Here, a localized surface plasmon resonance (LSPR) biosensor that enables the simple and rapid detection of DNase‐I is reported. Moreover, a novel technique named electrochemical deposition and mild thermal annealing (EDMIT) is applied to overcome signal variations. By taking advantage of the low adhesion of gold clusters on indium tin oxide substrates, both the uniformity and sphericity of gold nanoparticles are increased under mild thermal annealing conditions via coalescence and Ostwald ripening. This ultimately results in an approximately 15‐fold decrease in LSPR signal variations. The linear range of the fabricated sensor is 20–1000 ng mL−1 with a limit of detection (LOD) of 127.25 pg mL−1, as demonstrated by spectral absorbance analyses. The fabricated LSPR sensor stably measured DNase‐I concentrations from samples collected from both an inflammatory bowel disease (IBD) mouse model, as well as human patients with severe COVID‐19 symptoms. Therefore, the proposed LSPR sensor fabricated via the EDMIT method can be used for early diagnosis of other infectious diseases.
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