Ultrasensitive and High Reproducible Detection of Urinary Metabolites Using the Tip–Contact Extraction Method Coupled with Negative LDI-MS

Abstract

More and more evidence has proved that urinary metabolites can instantly reflect disease state. Therefore, ultra-sensitive and reproducible detection of urinary metabolites in a high-throughput way is urgently desirable for clinical diagnosis. Matrix-free laser desorption/ionization mass spectrometry (LDI-MS) is a high-throughput platform for metabolites detection, but it is encountered by severe interference from numerous salts in urine samples, because the crystallized urine salt on dried samples could result in poor reproducibility in LDI-MS detection. The present work proposed a tip−contact extraction (TCE) technique to eliminate interference from the urine salt. Vertical silicon nanowire arrays decorated with the fluorinated ethylene propylene film (FEP@VSiNWs) could effectively extract metabolites from the urine sample dropping on its surface. High salt tolerance was observed in the subsequent LDI-MS detection of the metabolites extracted on the tip of FEP@ VSiNWs even in the presence of 1 M urea. Stable and reproducible mass spectra for non-target metabolic analysis were obtained in real urine samples with different dilution folds. Urinary metabolites collected from bladder cancer (BC) patients were reliably profiled by the TCE method coupled with negative LDI-MS. Based on this platform, potential metabolic biomarkers that can distinguish BC patients and normal controls were uncovered.

Matrix- and Surface-Assisted Laser Desorption/Ionization Mass Spectrometry Methods for Urological Cancer Biomarker Discovery—Metabolomics and Lipidomics Approaches

“…Another SALDI MS method used in bladder cancer biomarker research was the technique utilizing vertical silicon nanowire arrays decorated with the fluorinated ethylene propylene film (FEP@VSiNWs), as proposed by Jiang and colleagues [ 49 ]. The proposed methodology involved not only measuring LDI MS from the developed systems but also desalting and concentrating urine samples, thereby allowing for the detection of a greater number of metabolites.…”

Nanomaterials‐assisted metabolic analysis toward in vitro diagnostics

“…As a critical component in an electrochemical system, electrodes produce electric signal outputs by interacting with the targeted analytes. Recently, nanomaterials have inched their way into the design and fabrication of electrodes to improve electrochemical responses, due to large surface area (e.g., various nanosheets [ 27–33 ] ) and superior electrochemical properties (e.g., carbon nanotubes [ 40–43 ] and silicon nanowires [ 44–47 ] ). Typically, the nanomaterial‐based electrodes for metabolic analysis can be subclassified into three types according to the material functions, including (1) facilitating enzymatic reactions of the original electrodes; (2) serving as nanozymes with enhanced catalytic activities for replacing natural enzymes; and (3) acting as substrates of non‐enzymatic electrodes with direct electrocatalytic oxidation and good stability.…”

Rapid Diagnosis of Urinary Tract Cancers on a LEGO-Inspired Detection Platform via Chemiresistive Profiling of Volatile Metabolites

“…Other common methods for the detection of cancer markers focus on the chromatographic or mass spectrometric strategies in combination with sophisticated molecular diagnostics to target proteins, lipids, or microRNAs, , which is often limited by heavy dependence on well-trained personnel and centralized facilities. On the other hand, volatile metabolites are indicative of the physiological and pathological conditions of individuals and have emerged as a class of ideal biomarker candidates for noninvasive determination of cancer diseases. , Not until recently have polyaniline- or Mxene-based chemiresistive sensor arrays been reported for early screening of bladder cancer or diabetes through vapor analysis in urine, , yet a field-deployable strategy that can decipher multiplexed electrochemical readouts for comprehensive discrimination of phenotypically similar UTCs is still in urgent need.…”

“…On the other hand, volatile metabolites are indicative of the physiological and pathological conditions of individuals and have emerged as a class of ideal biomarker candidates for noninvasive determination of cancer diseases. 18,19 Not until recently have polyaniline-or Mxene-based chemiresistive sensor arrays been reported for early screening of bladder cancer or diabetes through vapor analysis in urine, 20,21 chemical readouts for comprehensive discrimination of phenotypically similar UTCs is still in urgent need. Despite the advantages in cross-reactivity and portability, the development of array-based chemiresistive sensing technology has been challenged by drawbacks including high operating temperatures, limited data dimensionality, and difficulty in sensors' fabrication.…”