RESUMO
Quantitative imaging of amyloid beta (Aß) in brain is of great significance for pathological study and follow-up drug development of Alzheimer's disease (AD). In this work, a method using antibody-conjugated gold nanoparticles (AuNPs) was established for quantitative imaging of Aß peptide in the brain of AD mouse by Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Aß antibody (Anti-Aß) was labeled with AuNPs to form the conjugate AuNPs-Anti-Aß which was immunoreactive with Aß in the brain slice of mouse. Quantitative imaging of Au was acquired with homogenized brain slice matrix-matched standards as external calibrants which were made by immersing in gold standard solution with different concentrations. Furthermore, the stoichiometric ratios between metal conjugates and Aß were optimized, and the immunoreaction efficiency after labeling was also investigated. According to the molar relationship between AuNPs and Anti-Aß (1:4.3) and the ratio of Anti-Aß to Aß (1:1), quantitative imaging of Aß in brain was accomplished. The method intuitively displayed the location and concentration of Aß aggregation, which was consistent with traditional immunohistochemical staining. Since the numerous gold atoms contained in AuNPs can enhance the signal of Aß, the method is more intuitive and sensitive. The proposed methodology is potential in investigating the quantitative imaging of biomarker heterogeneity, and is useful to understand such complex brain mechanisms in the future.