Gold nanoflower‐based surface‐enhanced Raman probes for pH mapping of tumor cell microenviroment

Abstract

Objectives Early diagnosis of tumour cells is critically important for cancer treatment. Given that the tumour environment is slightly acidic, the pH value of the cell environment can be used as a criterion for tumour diagnosis. However, mapping pH in the cell environment with high resolution, high sensitivity and accuracy remains challenging. Materials and Methods Based on gold nanoflower as surface‐enhanced Raman scattering (SERS) substrate loading with p‐mercaptobenzoic acid (MPA) as pH‐responsive Raman reporter, a new SERS nanoprobe for pH mapping was developed. Results This probe showed a characteristic Raman spectrum signal in response to the different pH in solutions or cells. The signal intensity is positively correlated to the pH value. Moreover, this probe is self‐correctable, which can help eliminate the influence of probe concentration on the accuracy of pH measuring. Conclusions We demonstrate the pH mapping of cell environment using the probe, which can be used to distinguish normal cells and tumour cells. This method may provide a new imaging tool for early diagnosis of cancer.

Toward Sensitive and Reliable Surface-Enhanced Raman Scattering Imaging: From Rational Design to Biomedical Applications

“…Better stability and biocompatibility of Au enable it to be the most widely used SERS-active material for in vivo application. 23 Except for the basic nanosphere and nanorod, considerable research has been dedicated to developing substrates with high performance of signal amplification, such as nanotube, 24 nanostar, 25 nanocage, 26 nanoflower, 27 nanomushroom, 28 nanocoral, 29 etc., as shown in Figure 1. These specially shaped structures form sharp points or spikes on the surface of the nanoparticles, generating additional hot spot regions and enhancing SERS signals with the local electromagnetic field.…”

“…(i) TEM image of AuNFs; (ii) TEM image of single AuNF and its interior nanogap; (iii) UV–vis spectra of AuNPs and AuNFs; (iv) finite-difference time-domain simulation of electromagnetic field distribution of AuNFs. Adapted with permission from ref . Copyright 2019 John Wiley and Sons.…”

Recent Progress of SERS Nanoprobe for pH Detecting and Its Application in Biological Imaging

“…At present, the sensitive molecules mainly used to construct pH SERS probes are some carboxyl, amino and pyridine rings containing three kinds of functional groups with pH response. Among them, the three most representative signal molecules are 4-mercaptobenzoic acid (4-MBA) [23][24][25], 4-mercaptopyridine (4-Mpy) [26][27][28], 4-aminobenzene mercaptan (4-ATP) [19,29,30], etc. pH sensitive molecules are usually bound together by the formation of sulfhydryl groups and amino groups with precious metals.…”

“…It can also be used for in situ pH detection of human skin (Figure 2d). Xie et al [23] based on gold nanoflower as SERS substrate loading with 4-MBA to develop a new SERS nanoprobe for pH mapping, which can be used to distinguish normal cells and tumor cells. Monica et al [24] fixed 4-mercaptobenzoic acid onto the surface of chitosan-coated silver nanotriangles to generate a robust pH SERS traceable system.…”

Recent Progress of SERS Nanoprobe for pH Detecting and its Application in Biological Imaging

“…At present, the sensitive molecules mainly used to construct pH SERS probes are some carboxyl, amino and pyridine rings containing three kinds of functional groups with pH response. Among them, the three most representative signal molecules are 4-mercaptobenzoic acid (4-MBA) [21][22][23], 4-mercaptopyridine (4-Mpy) [24][25][26], 4-aminobenzene mercaptan (4-ATP) [27,28], etc. pH sensitive molecules are usually bound together by the formation of sulfhydryl groups and amino groups with precious metals.…”