Strategy for In Situ Imaging of Cellular Alkaline Phosphatase Activity Using Gold Nanoflower Probe and Localized Surface Plasmon Resonance Technique

Abstract

In this work, a simple and ultrasensitive localized surface plasmon resonance (LSPR) method that use Au nanoflowers (AuNFs) as a probe was designed for in situ monitoring of alkaline phosphatase (ALP) activity. The AuNFs were fabricated by hydrogen tetrechloroaurate-induced oxidative disruption of polydopamine-coated Au nanoparticles (AuNPs), and subsequently, growth of Au nanopetals on AuNPs occurred. The as-prepared AuNFs showed a much higher LSPR capability and stronger scattering color change than AuNPs. The strategy for in situ cellular ALP activity detection relied on the deposition of Ag on the AuNFs surface, which changed the morphology of AuNFs and led to a tremendous LSPR response and scattering color change. The deposition of Ag shell on AuNFs was related to ALP activity, where ALP catalyzed the hydrolysis of L-ascorbic acid 2-phosphate sesquimagnesium salt hydrate to form Lascorbic acid (AA), and then AA reduced Ag + to Ag and deposited onto AuNFs. With this concept, the ALP activity could be monitored with a detection limit of 0.03 μU L −1 . Meanwhile, the ALP activity of single HepG2 cells and HEK 293 cells was tracked with a proposed approach, which indicated the trace expression level of ALP in HEK 293T cell and overexpressed level of ALP in HepG2 cells. After treatment with drugs, the cellular ALP activity of HepG2 cells was decreased with the treating time and dose increasing. Therefore, the proposed strategy could be used for tracking the cellular ALP activity, which paved a new avenue for cell studies and held great potential for discovering novel ALP-based drugs applications.

Recent Advances in Plasmonic Nanostructures Applied for Label‐free Single‐cell Analysis

“…With the aid of spectrometer, the individual dark‐field scattering spectrum of single plasmonic nanostructure can be obtained, which is contributed to the biosensing and diagnostic at the single particle/cell level [61]. It is reported that deposition of Ag on the Au nanoflowers (AuNFs) surface could be used for in situ monitoring of alkaline phosphatase (ALP) activity (Figure 7a) [62]. The deposition of Ag shell changed the morphology of AuNFs, leading to the tremendous LSPR response and scattering color change, which was related to ALP activity.…”

Overview of Optical and Electrochemical Alkaline Phosphatase (ALP) Biosensors: Recent Approaches in Cells Culture Techniques

“…Sappia et al (2017) researched SPR for the real time detection of ALP by using WGA-modified surfaces, where ALP absorbs and the signal increases [90]. Wang et al (2018) created a probe using gold nanoflower in detecting cellular ALP and found that the ALP activity could be detected up to limits of about 0.03 μU L −1 [91]. In addition, the ALP activity of the mammalian cells was able to be attracted using the develop probe.…”

Gold Nanorod Array-Bridged Internal-Standard SERS Tags: From Ultrasensitivity to Multifunctionality

“…20,21 Although silver coating is beneficial for signal enhancement of Au@Ag NPs, some problems related to the surface topography variation exist. Silver randomly grew on the cores without any site and density regulation, which tended to smooth the surface of core NPs, merging the tips, holes, or junctions of the core NPs (especially for nanoflowers 22 and nanostars 10 ). Thus, the resultant bimetallic NPs were usually spherical and smooth and lost the intrinsic hotspots of the cores.…”