Surface chemical approach to single-step measurement of antibody in human serum using localized surface plasmon resonance biosensor on microtiter plate system

Abstract

In clinical settings, serum antibody levels serve as markers of pathology. For example, antibodies related to autoimmune diseases are among the conventional targets in laboratory tests. Simple clinical tests can improve the efficacy of laboratory practice. This study describes a single-step, wash-free technique for optically detecting antibodies in human serum through the localized surface plasmon resonance (LSPR) of gold nanoparticles. As a proof-of-concept experiment, the amount of antibiotin dissolved in human serum was measured with a LSPR-based biosensor in a wash-free manner using a conventional 96-well microtiter plate and a plate reader. For an efficient surface modification of biosensors, zwitterionic copolymer was used as a scaffold on the gold nanoparticle surface to immobilize antigen and blocking reagent. Single-step, wash-free measurement of antibiotin in human serum was successfully achieved. In addition, nonspecific responses from serum contents were significantly reduced because both the copolymer and hydrophilic antigen reagent that we employed were composed of poly(ethylene oxide) spacer. Comparative experiments of the antigen-antibody reaction in serum to that in buffered solution revealed that serum is a favorable environment for the biological reaction. In conclusion, our gold-nanoparticle-based LSPR method may provide a rapid and simple way to measure the amount of antibody in serum quantitatively in clinical practice.

Gold Nanoparticles for In Vitro Diagnostics

“…Another effective approach to increase refractive index is based on molecular binding events that happen on the surfaces of nanoparticles, where the increase of the mass of the biomolecules is likely to induce an enhancement of LSPR shift. 41 …”

“…An aptamer-antigen–antibody sandwich structure on AuNRs was obtained to enlarge the mass of the target of interest, thus leading to an enhanced LSPR shift. 36b,41a The functionalization of aptamer on AuNRs brings two advantages. First, the activity of aptamer can be regenerated when the captured targets are washed away by concentrated salt solutions.…”

“…Several other LSPR sensors for immunodetection have been reported for the biomarkers and showed high sensitivity and simplicity when combined with other ease-of-use formats such as microfluidics, microtiter plate system, or optical fiber. 41b,52 …”

Biosensors and nanobiosensors for therapeutic drug and response monitoring

“…The main advantages of LSPR over SPR are that multiplexing is easily achievable and 96-well plate formats have been reported. 79,80 Also, the instrumental requirements are minimal and devices can be easily miniaturized and previous problems involving lack of uniformity in the nanoparticles have now been greatly improved by developments in nanofabrication techniques. 71 Finally, contrary to SPR, the detection of small molecules is possible with LSPR as mentioned previously.…”

Integration of nanomaterials for colorimetric immunoassays with improved performance: a functional perspective

“…63 One key step for preparing LSPR sensors is immobilizing nanostructures on a bulk surface such as glass. Even though different surface immobilization techniques have been developed, [64][65][66] poor adhesion still remains to be a tough problem for LSPR assays. To address this issue, nanolithography has been developed as an inexpensive, simple, highthroughput nanofabrication technique to prepare a wellordered 2D nano array with tunable parameters.…”