and the concomitant elevation of lactate in the interstitial fluids due to the enhanced glycolysis energy metabolism. [1] Accurate profiling of medically relevant metabolites in human body fluids provides molecular information for deep understanding of pathological mechanism at a more distal level than genomic analysis, and enables precise diagnosis and treatment of the underling diseases. [2] Till now, different advanced techniques, including magnetic resonance spectroscopy, [3] mass spectrometry, [4] and chromatography coupled mass spectroscopy, [5] have been developed to measure metabolites in vitro and in vivo. While useful, these techniques require sophisticated and expensive equipment, hampering their use in rapid point-ofcare clinical testing. By contrast, enzymebased bioassays, where the presence of analytes is optically or electrochemically detected through the highly specific and efficient enzymatic reaction, provide novel opportunities for detection metabolite biomarkers. [6] These approaches show enough figures of merits regarding device portability, speed, sample consumption and cost. However, the inherent instability of enzyme at elevated temperature, in circumstance containing digestive enzymes or chemical chelates, and when storing the enzyme long-term represents a longstanding yet largely unsolved challenge that leads to poor reproducibility and accuracy in enzyme-based metabolite analysis. [7] Reliable monitoring of metabolites in biofluids is critical for diagnosis, treatment, and long-term management of various diseases. Although widely used, existing enzymatic metabolite assays face challenges in clinical practice primarily due to the susceptibility of enzyme activity to external conditions and the low sensitivity of sensing strategies. Inspired by the micro/ nanoscale confined catalytic environment in living cells, the coencapsulation of oxidoreductase and metal nanoparticles within the nanopores of macroporous silica foams to fabricate all-in-one bio-nanoreactors is reported herein foruse in surface-enhanced Raman scattering (SERS)-based metabolic assays. The enhancement of catalytical activity and stability of enzyme against high temperatures, long-time storage or proteolytic agents are demonstrated. The nanoreactors recognize and catalyze oxidation of the metabolite, and provide ratiometric SERS response in the presence of the enzymatic by-product H 2 O 2 , enabling sensitive metabolite quantification in a "sample in and answer out" manner. The nanoreactor makes any oxidoreductase-responsible metabolite a candidate for quantitative SERS sensing, as shown for glucose and lactate. Glucose levels of patients with bacterial infection are accurately analyzed with only 20 µL of cerebrospinal fluids, indicating the potential application of the nanoreactor in vitro clinical testing.

The monitoring of metabolites in biofluids provides critical clues for disease diagnosis and evaluation. Yet, the quantitative detection of metabolites remains challenging for surface-enhanced Raman spectroscopy (SERS) due to poor reproducibility in preparation and manipulation of SERS nanoprobes. Herein, we develop an activity-based, slippery liquid-infused porous surface SERS (abSLIPSERS) sensor for facile quantification of metabolites with unmodified naked metal nanoparticles (NPs) by integrating biocatalysis-boronate oxidation cascades with SLIPSdriven self-concentration and delivering. Upon mixing the target metabolite with a specific oxidase, a H 2 O 2 -sensitive phenylboronate probe, and the naked Au NPs, H 2 O 2 produced from the biocatalytic reaction oxidizes the phenylboronate probe to phenol, resulting in a ratiometric SERS response. Meanwhile, the SLIPS enables the complete enrichment of molecules and NPs within an evaporating liquid droplet, delivering the probes to the SERS-active sites for Raman amplification. Compared with conventional SERS biosensors, abSLIPSERS avoids multistep synthesis and biofunctionalization of nanoprobes, which significantly simplifies the detection workflow and improves the reproducibility. The abSLIPSERS sensor also shows tunable dynamic range beyond 4 orders of magnitude and allows quantifying any other metabolites with specific enzymes. We demonstrate abSLIPSERS sensing of lactate, glucose, and choline in human serum for exploring energy metabolism in lung cancer. This study opens up a new opportunity for future point-of-care testing of circulating metabolites by SERS and will help to facilitate the translation of SERS bioanalysis to clinical settings.

Lung cancer (LC) remains the most commonly diagnosed cancer. Timely diagnosis is crucial to improve the clinical outcomes of LC patients. Serum molecular patterns reflect the physiological and pathological status...