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Owing to its promising biocompatibility and reliable sensitivity, semiconductor-guided surface-enhanced Raman scattering (SERS) technology has aroused widespread concern in clinical immunoassays. Herein, the well-improved light capture capability of MoS2 with a novel three-dimensional (3D) flower-like morphology was combined with the synergistic chemical enhancement from a MoS2@red phosphorus (RP) hybrid system, facilitating an attractive non-metallic SERS-based detection of ferritin in serum. Owing to the remarkable enhancement factors of both the immunoprobe and immunosubstrate, which were comparable to noble metal, an extremely low limit detection of 11.5 pg mL−1 was achieved in the absence of fluorescence interference. In particular, the trace ferritin in the clinical serum sample was successfully monitored, demonstrating superior sensitivity to the traditional chemiluminescent method. Overall, this study convincingly revealed the feasibility and reliability of SERS-based immunoassays induced by biocompatible semiconductors, which has opened a new way to implement the detection and tracking of biomarkers in the human body. [ABSTRACT FROM AUTHOR]

It holds extreme significance in expansive fields to promote the sensitivity and quantitative aptitudes of surface-enhanced Raman scattering (SERS) substrate. Herein, a distinctive piezoelectric polyvinylidene fluoride (PVDF) film combined with hydrophilic-hydrophobic strategy was ventured into SERS technique to facilitate a superior self-energized hybrid substrate. Notably, enhanced localized electromagnetic field of Ag nanoparticles (Ag NPs) could be rationally induced by pressing or bending the PVDF film, enabling a tunable ultra-high sensitivity. The quantitative level of the sensitive detection was further improved by employing a facile hydrophilic-hydrophobic strategy to uniformly anchor and enrich analytes, ascertaining a low variation of 11.8%. As a proof-of-concept, an in-situ collection and assay of enrofloxacin residue on fishes with different surface roughness were successfully accomplished by the pressed substrate and trustworthy recovery rates were demonstrated. Briefly, the hydrophilic-hydrophobic self-energized PVDF-Ag hybrids demonstrated superior SERS enhancement with a promising uniformity, providing a novel and practical design options for sensing devices and facilitating the noninvasive monitoring of residue in sea food. [Display omitted] • A novel kind of self-energized E-SERS substrate with a tunable ultra-high sensitivity was developed. • An facile hydrophilic-hydrophobic strategy was used to improve the accuracy of the E-SERS signal. • A practical monitoring of enrofloxacin residue on fishes was achieved by the self-energized substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gold and silver nanoparticles have been homogeneously disseminated on BP nanosheet by a light-assisted self-reduction. • Robust SERS chips were successfully developed by assembling BP@Au-Ag nanocomposites into bilayer membrane. • A reliable in-situ recyclable detection strategy has been demonstrated utilizing the tape-mediated SERS chip. • The effective preservation of BP was realized based on the principle of fresh-keeping film. Self-cleaning surface-enhanced Raman scattering (SERS) substrates dependent on versatile two-dimensional semiconductors offer an efficient channel for the sensitive monitoring and timely degradation of hazardous molecules. Herein, a kind of sophisticated SERS-active nanocomposites was developed by incorporating Au-Ag nanoparticles onto black phosphorus (BP) nanosheets via photo-induced self-reduction. Combining the substantial electromagnetic "hot spots" triggered by bimetallic plasma coupling effect and the efficient charge transfer from BP to probe molecules, the proposed nanocomposites featured attractive SERS enhancement, facilitating a limit of detection down to 4.5 × 10−10 M. Attributed to the remarkable restriction of electron-hole recombination stemming from "Schottky contact", the photocatalytic activity of BP was prominently boosted, demonstrating a complete degradation time as short as 65 min. Furthermore, the disgusting instability of BP was considerably hindered by inserting the nanocomposites into various bilayer matrices with diverse hardness and viscosity inspired by cling film principle. Moreover, a significantly elevated collection rate high to 93.1% for in-situ detection was also achieved by the as-manufactured flexible SERS chips based on tape. This study illustrates a clear perspective for the development of versatile BP-based SERS chips which might facilitate sensitive analysis and treatment of perilous contaminants in complicated real-life scenarios. [ABSTRACT FROM AUTHOR]

Non-metallic surface-enhanced Raman scattering (SERS) demonstrates an attractive potential in clinical immunoassay thanks to the brilliant biocompatibility and chemical enhancement of semiconductor substrates. Herein, SERS-based quantitative assay of SARS-CoV-2 in saliva was carried out by constructing SiC@RP nanotowers (NTs) and Si nanoparticles. Ascribed to the efficient light absorption and molecular enrichment capacity of the hierarchical tower morphology as well as the synergistic chemical enhancement in the semiconductor heterojunction, the SiC@RP NTs achieved a minimum limit of detection as 7.6 × 10-11 g/mL for SARS-CoV-2. Concurrently, the correction of the detection signal by the intrinsic Raman signal of Si nanoparticles drastically improved the stability and reliability of the detection, facilitating a relative standard deviation (RSD) data within ± 9.53%. Ultimately, the real-time SERS monitoring of saliva samples displayed an ultra-high response rate of no less than 83.2%. Such a non-metallic SERS immunoassay with high sensitivity and attractive reliability is expected to play a key role in future clinical monitoring application. • Sensitivity was enhanced by utilizing the synergistic chemical enhancement of SiC@RP compound semiconductor. • Light-limiting effect and molecular enrichment was improved by the unique morphology of SiC nanotowers. • The intrinsic Raman signal of silicon probes was used as an internal standard signal. • High throughput detection of SARS-CoV-2 in saliva with a LOD of 7.6 × 10-11 g/mL was realized. [ABSTRACT FROM AUTHOR]

Internal standard-mediated quantitative surface enhanced Raman scattering (SERS) technique has been restricted due to the reduction and collapse of intrinsic Raman signal after further modification. Alternatively, the concept of tunable internal standard was proposed and investigated here for its attractive prospect in practical application. Specifically, a recyclable PMMA@MoS 2 @Ag composite SERS substrate was firstly developed to enable not only the sensitive in-situ detection of pernicious molecules, but also their efficient green diminishing. Furthermore, a tailorable Raman internal standard at 520 cm−1 was developed to promote the quantification degree of the above detection by simply tuning the number of silicon nanoparticles (Si NPs) in the NaCMC polymer matrix. The obtained flexible NaCMC-Si/PMMA@MoS 2 @Ag hybrid substrate with enhancement factors from 1.86 × 106 to 2.88 × 109, reliable self-cleaning ability, and robust quantification effect was finally conducted in the in-situ monitoring and diminishing of mixed thiabendazole (TBZ) and vanillin (VA) on tobacco, achieving an ultra-low limit of detections as about 10−7 M and recovery rates higher than 87%. In summary, the proposed sophisticated substrate with both green degradation capability and tunable internal standard is expected to broaden the application of SERS technique in practical biochemical monitoring. [Display omitted] • The concept of tunable internal standard was proposed and investigated here. • A flexible NaCMC-Si/PMMA@MoS 2 @Ag SERS substrate with self-cleaning ability and quantification effect was developed. • The in-situ monitoring and diminishing of mixed hazardous molecules on tobacco were achieved. [ABSTRACT FROM AUTHOR]

It is tremendously desirable for the timely and effective detection of cancer to facilitate the ultra-highly sensitive monitoring of tumor marker in clinical serum sample. In this study, an electromagnetic and chemical synergistically enabled recyclable immunoassay based on surface-enhanced Raman scattering (SERS) was proposed by realizing the anisotropic growth of sea-urchin-like gold nanoflowers (Au NFs) on two-dimensional red phosphorus (RP) nanoplates. Besides the achieved enhancement factor as high as 2.24 × 106, it was found that the photocatalytic and SERS activities were kept at a high level for the hybrid substrate of RP/Au NFs throughout 7 cycles of immunoassay. In combination with a non-metallic immunoprobe, the limit of detection was drove to 7.41 × 10−5 IU·mL−1 for cancer antigen 19–9. The comparative experiments of nonspecific monitoring verified the promising selectivity of this strategy. Considering the intriguing features of high sensitivity, recyclability, and specificity, the proposed multifunctional RP/Au NFs exhibited its superior role in the early detection of cancer and can be adapted for point-of-care diagnosis. ► A symmetric Au nanoflowers have been successfully decorated onto the RP nanosheet. ► Abundant bright "hot spots" around decorated sea-urchin-like Au nanoflowers were confirmed. ► A recyclable immunoassay strategy has been demonstrated by RP/Au NFs hybrid substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible biomimetic SERS substrates were fabricated by nanoimprint technology. • Linear relationship in SERS detection was significantly corrected by the intrinsic Raman peak of PDMS. • The significance of manufacturing highly conformed micro/nanofabrication from the surface to be tested was pointed out. Although biomimetic surface enhanced Raman scattering (SERS) substrate which makes use of naturally existing raw materials have been fully utilized, it remains challenging to achieve credible quantitative detection. Herein, nanoimprint technology was exploited to engineer internal standard (IS) enabled quantitative flexible biomimetic SERS substrates, in which polydimethylsiloxane (PDMS) with intrinsic Raman signal was utilized as a tool to reversely duplicate surface structures from different agriculture products and then deposited with Ag nanoparticles. The resultant four kinds of biomimetic SERS substrates with different surface geometries all permit highly sensitive assay with enhancement factors (EFs) of about 106 in both drop-dry and in situ SERS detection modes. Moreover, the quantitative degree in the SERS detection was effectively corrected based on the IS strategy. Finally, an ingenious interactive in situ SERS detection was conducted. Interestingly, the maximum recovery rate was achieved when the template food was used as target surface compared with other foods, indicating the significance of manufacturing the highly conformed SERS-active structure from the surface to be tested. The proposed quantitative biomimetic SERS substrate is expected to be widely used in the field of biochemical supervision. [ABSTRACT FROM AUTHOR]

Recently, nonmetallic substrates have stimulated great interest in surface-enhanced Raman scattering (SERS)-based immunoassay owing to their good uniformity, stability, and biocompatibility. In this context, a novel nonmetallic SERS-based immunoassay mediated by two-dimensional molybdenum disulfide (MoS 2) was delivered for the sensitive and specific monitoring of carbohydrate antigen 19–9 (CA19-9). The effective enrichment of molecules on the large active surfaces of MoS 2 as well as potential 532-nm laser-induced charge transfer resonances between them engendered desirable enhancement factor values at the level of 105. Intriguingly, a sandwich immunocomplex combined MoS 2 nanoflower and nanosheet exhibited not only a wide linear range from 5 × 10−4 to 1 × 102 IU·mL−1 but also a limit of detection as low as 3.43 × 10−4 IU·mL−1 towards CA19-9. More meaningful, the analytical result for clinical patient serum sample was basically compared with the conventional chemiluminescent immunoassay. Such a novel nonmetallic SERS-based immunosensor with desirable biocompatibility and sensitivity is promising for clinical diagnosis. • A novel nonmetallic SERS-based immunoassay mediated by two-dimensional molybdenum disulfide (MoS 2) was developed. • Potential 532-nm laser-induced CT resonances between MoS 2 and R6G engendered a fascinating EF value of 105. • The sensitive and specific monitoring of carbohydrate antigen 19–9 in human serum has been achieved by the nonmetallic SERS-based immunoassay. [ABSTRACT FROM AUTHOR]

Aiming to augment the reliability and efficiency of surface enhanced Raman scattering (SERS)-active immunoprobe, sophisticated strategies that are able to avoid the dissociation of Raman molecules and noble metal nanoparticles (NPs) in practice have drawn a considerable attention. This study confirmed that Ag@polystyrene-block-poly(acrylic acid)@Ag core-shell nanostructures possessed superior stability compared with bare Ag NPs in phosphate buffer saline solution and human serum. Combined with a unique paper-based immunosubstrate with a satisfying enhancement factor of 9.71 × 105, a robust sandwich immunostructure was constructed and conducted to monitor carbohydrate antigen 19-9 (CA19-9), presenting a low limit of detection of about 10−4 U/mL. With these exceptional features, such a proposed protocol was finally utilized to detect CA19-9 in several clinical human sera, which shown much higher sensitivity than the traditional chemiluminescence analysis. [Display omitted] • A type of reliable triple core-shell Ag@PSPAA@Ag NMs was proposed to perform as a stable and reliable immunoprobe. • A flexible immunosubstrate based on Ag-decorated filter paper with an enhancement factor (EF) of 9.71 × 105 was demonstrated. • A reliable monitoring of carbohydrate antigen 19-9 with concentration as low as 100 fg/mL was realized. [ABSTRACT FROM AUTHOR]