Diagnosis in a Preclinical Model of Bladder Pain Syndrome Using a Au/ZnO Nanorod-based SERS Substrate

Abstract

To evaluate the feasibility of ZnO nanorod-based surface enhanced Raman scattering (SERS) diagnostics for disease models, particularly for interstitial cystitis/bladder pain syndrome (IC/BPS), ZnO-based SERS sensing chips were developed and applied to an animal disease model. ZnO nanorods were grown to form nano-sized porous structures and coated with gold to facilitate size-selective biomarker detection. Raman spectra were acquired on a surface enhanced Raman substrate from the urine in a rat model of IC/BPS and analyzed using a statistical analysis method called principal component analysis (PCA). The nanorods grown after the ZnO seed deposition were 30 to 50 nm in diameter and 500 to 600 nm in length. A volume of gold corresponding to a thin film thickness of 100 nm was deposited on the grown nanorod structure. Raman spectroscopic signals were measured in the scattered region for nanometer biomarker detection to indicate IC/BPS. The Raman peaks for the control group and IC/BPS group are observed at 641, 683, 723, 873, 1002, 1030, and 1355 cm^-1, which corresponded to various bonding types and compounds. The PCA results are plotted in 2D and 3D. The Raman signals and statistical analyses obtained from the nano-sized biomarkers of intractable inflammatory diseases demonstrate the possibility of an early diagnosis.

Keywords: ZnO nanorods; interstitial cystitis/bladder pain syndrome (IC/BPS); principal component analysis (PCA); surface enhancement Raman spectroscopy (SERS).

Figure 1

Schematic showing the production process, measurement, and analysis process of the ZnO nanorod-based SERS sensing chip.

Figure 2

(a) Measurement of voiding function in the control group and the IC/BPS animal group at 7 days after HCl treatment. Optical microscope images of a Raman measurement region diffused from a sample droplet into a nanoporous area, indicated by red arrows: (b) 10× and (c) 40× objective.

Figure 3

FE-SEM images of urine dropped on a SERS substrate: (a) 250 times magnification, containing a dried droplet, diffused area, and bare SERS area; (b) 5k and (c) 50k magnification showing the interface between the diffused and bare area; (d) cross-sectional image showing Au-coated ZnO nanorods.

Figure 4

Averaged Raman spectra for all samples (black line), for IC/BPS (blue line), and control (red line) of rat’s urine. Standard deviations are painted around the spectra, and the main peaks marked by bands are due to nanometer-scale bio-markers.

Figure 5

Principal component analysis results for urine of IC/BPS and control sample: (a) PC1 (39.23%) vs. PC2 (17.09%); (b) PC1 vs. PC3 (9.49%); (c) PC2 vs. PC3; (d) 3D plot of PC1, PC2, and PC3.