Antibody-Conjugated Nanodiamonds as Dual-Functional Immunosensors for In Vitro Diagnostics
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2023-08-03 |
| Journal | Analytical Chemistry |
| Authors | TrongāNghia Le, HsināYi Chen, Xuan Mai Lam, C.R. Wang, HuanāCheng Chang |
| Institutions | National Taiwan Normal University, National Taiwan University of Science and Technology |
| Citations | 18 |
Abstract
Section titled āAbstractāNanodiamonds (NDs) are carbon nanoparticles with a large refractive index, a high density, and exceptional chemical stability. When excited by green light, they can emit bright red fluorescence from implanted nitrogen-vacancy (NV) centers. Taking advantage of these properties, we have developed antibody-conjugated NDs as in vitro diagnostic sensors for two complementary assays: particle-enhanced turbidimetric immunoassay (PETIA) and spin-enhanced lateral flow immunoassay (SELFIA). To achieve this goal, monocrystalline diamond powders (ā¼100 nm in diameter) with or without NV implantation were first treated in molten KNO<sub>3</sub> to reduce their size and shape inhomogeneity, followed by surface carboxylation in strong oxidative acids and non-covalent conjugation with antibodies in water. PETIA and SELFIA were carried out separately with a microplate reader and a magnetically modulated fluorescence analyzer. Using C-reactive protein (CRP) as the target antigen, we found that anti-CRP-conjugated NDs exhibited high colloidal stability over 1 month at 4 Ā°C in buffer solution. The limits of detection for 3 Ī¼L of CRP sample solution were 0.06 Ī¼g/mL and 1 ng/mL with variation coefficients of less than 10 and 15% for PETIA and SELFIA, respectively. These two methods together provide a detection range of 1 ng/mL-10 Ī¼g/mL, potentially useful for clinical applications. This work represents the first practical use of rounded monocrystalline NDs as in vitro diagnostic reagents.