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In this work, a microfluidic chip using Au@SiO2 array–based highly active SERS substrates was developed for quantitative detection of squamous cell carcinoma antigen (SCCA) and carcinoembryonic antigen (CEA) associated with cervical cancer. The chip consisted of six functional units with pump-free design, enabling parallel detection of multiple samples in an automatic manner without external pumps and improving the portability. Ag nanocubes (AgNCs) were labeled with Raman reporters and coupled with antibodies (labeling) to prepare SERS tags, while the Au nanoparticle–modified SiO2 microsphere (Au@SiO2) array was conjugated with antibodies (coating) to generate the highly SERS-active capturing substrate. In the presence of target biomarkers, they were captured by SERS tags and capturing substrate, resulting in the formation of "sandwich" structures which were trapped in the detection chamber. As the immune reaction proceeded, a large number of "hot spots" were generated by the proximity of the Au@SiO2 array substrate and AgNCs, greatly amplifying SERS signals. With this chip, the limits of detection of the SCCA and CEA levels in human serum were estimated to be as low as 0.45 pg mL−1 and 0.36 pg mL−1, respectively. Furthermore, the good selectivity and reproducibility of this chip were confirmed. Finally, clinical serum samples were analyzed by this chip, and the outcomes were consistent with those of enzyme-linked immunosorbent assay (ELISA). Thus, the proposed microfluidic chip can be potentially applied for the clinical diagnosis of cervical cancer. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) remains a significant contributor to the global mortality rate, and a single biomarker cannot meet the specificity required for CRC screening. To this end, we developed a multiplexed, pump-free surface-enhanced Raman scattering (SERS) microfluidic chip (LoC-SERS) using a one-step recognition release mechanism; the aptamer-functionalized novel Au nanocrown array (AuNCA) was used as the detection element embedded in the detection zone of the platform for rapid and specific detection of protein markers in multiple samples simultaneously. Here, the corresponding aptamer specifically captured the protein marker, causing the complementary strand of the aptamer carrying the Raman signal molecule to be shed, reducing the SERS signal. Based on this platform, sensitive and specific detection of the target can be accomplished within 15 min with detection limits of 0.031 pg/mL (hnRNP A1) and 0.057 pg/mL (S100P). Meanwhile, the platform was consistent with ELISA results when used to test clinical. By substituting different aptamers, this platform can provide a new solution for the rapid and sensitive detection of protein markers, which has promising applications in future disease detection. [Display omitted] • A POCT platform was developed for rapid and sensitive detection of protein markers. • The prepared AuNCA has good SERS signal amplification effect. • The platform can complete the detection of a target in less than 15 min. • The platform has a promising application in clinical testing. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) based on the doubleantibody sandwich format is reported for the determination of carcinoembryonic antigen. Ordered gold nanobowl arrays were fabricated and conjugated with anticarcinoembryonic as capturing substrates, and gold nanoshells, adsorbed with 4-mercaptobenzonic acid, were modified with anticarcinoembryonic antigen as labeling tags. After the carcinoembryonic antigen was captured on ordered gold nanobowl arrays, the labeling tags were bonded to the captured carcinoembryonic antigen. The interaction of SERS substrates (ordered gold nanobowl arrays) and SERS labels (gold nanoshells) showed high sensitivity and a low detection limit for carcinoembryonic antigen. The linear dynamic range of SERS for carcinoembryonic antigen was from 5 pg/mL to 100 ng/mL with a linear relationship between carcinoembryonic antigen concentration and SERS intensity. The detection limit was 1.73 pg/mL. SERS detection may be used for other cancer biomarkers and provides potential for the clinical diagnosis of cancer biomarkers. [ABSTRACT FROM AUTHOR]

In this work, Au nanobowl (AuNB) arrays and the hybridization chain reaction (HCR) were utilized to develop a surface-enhanced Raman scattering (SERS) microfluidic chip for the ultrasensitive and simultaneous detection of squamous cell carcinoma antigen (SCCA) and cytokeratin 19 fragment antigen 21–1 (CYFRA21–1) in the serum of cervical cancer patients. Antibody-oligonucleotide conjugates were adopted as triggers, which initiated HCR by the hybridization between hairpin DNAs that were modified on Raman reporters-labeled Ag nanocubes, forming nicked double-stranded DNAs on AuNB arrays and leading to SERS signal amplification. Good linear response in the range of 10-12 – 10-6 g/mL, with an ultralow limit of detection for SCCA (0.08 pg/mL) and CYFRA21–1 (0.13 pg/mL), was achieved. Furthermore, the experiments demonstrated that the chip was feasible, time-efficient, and selective. The proposed chip was successfully applied to detect SCCA and CYFRA21–1 in clinical samples, and the results were consistent with those of enzyme-linked immunosorbent assay. Since most protein biomarkers in serum lack the corresponding aptamers, this method, which establishes antibody-oligonucleotide conjugates to trigger HCR, provides a general signal amplification technology for detecting protein biomarkers and exhibits good potential in clinical applications. • A SERS microfluidic chip based on AuNBs array and HCR was developed and employed for clinical detection. • Antibody-oligonucleotide conjugates were established to connect with targets and initiate HCR for signal amplification. • The assay possessed high sensitivity, with LODs as low as 0.08 pg/mL for SCCA and 0.13 pg/mL for CYFRA21-1. • The SERS microfluidic chip realized automatic flow by hydrophilic treatment and comb-like structure channels. [ABSTRACT FROM AUTHOR]

Lung resident mesenchymal stem cells (LR-MSCs) are important regulators of pathophysiological processes including tissue repair and fibrosis, inflammation, angiogenesis and tumor formation. Therefore, increasing attention has focused on the functional differentiation of LR-MSCs. However, the distinction between the undifferentiated and differentiated LR-MSCs, which are closely related and morphologically similar, is difficult to achieve by conventional methods. In this study, by employing the TAT Peptide-conjugated Au nanostars (AuNSs) as an intracellular probe, we developed a method for the identification of LR-MSC differentiation by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra were analyzed using principal component analysis (PCA) that allowed unambiguous distinction of subtypes and monitoring of component changes during cellular differentiation. Furthermore, to ascertain whether co-culture with alveolar epithelial type II (ATII) cells and incubation with transform growth factor (TGF)-β were involved in regulating the differentiation of LR-MSCs, we investigated the protein expression levels of epithelial markers and fibroblastic markers on LR-MSCs. Our results demonstrated that co-culture with ATII cells or incubation with TGF-β could induce the differentiation of LR-MSCs as confirmed by SERS analysis, a method that is capable of noninvasive characterization of and distinction between subtypes of LR-MSCs during differentiation. We have provided a new tool that may facilitate stem cell research. [ABSTRACT FROM AUTHOR]

[Display omitted] • A competitive recognition binding strategy regarding the aptamer was designed. • An integrated SERS-enabled LoC system was fabricated for gastric cancer detection. • VEGF and PDGF-B in human serum was directedly quantified with an ultralow LOD. Multiplex detection of biomarkers is nontrivial for gastric cancer diagnosis. Herein, we presented a lab-on-a-chip surface-enhanced Raman scattering (LoC-SERS) sensing system for the detection of vascular endothelial growth factor (VEGF) and platelet-derived growth factor-B (PDGF-B). The sensing system includes three parallel channels, each channel consists of two detection chambers, enabling the simultaneous analysis of multiple samples. The capillary structure provides self-driving power without the need of external pumps. The ordered gold nano-bipyramids (GNBPs) array in the detection chamber can form uniform and dense "hot spots", due to the homogeneous double-tip structure and narrow gaps, resulting in better SERS performance. During the analysis process, VEGF and PDGF-B in the serum can lead to the change of aptamer conformation. Raman reporter-labeled complementary DNA is shed from the aptamer due to competition of the target. The entire process only requires 20 min, which is rapid. By monitoring the changes in Raman intensity and fitting it with the logarithm of concentration, the correlation between the intensity and concentration can be clearly reflected as a mathematical relationship. The LoC-SERS sensing system has been verified to have excellent selectivity and reproducibility. Via the sensing system, the limits of detection (LOD) of VEGF and PDGF-B are as low as 0.342 pg/mL and 0.265 pg/mL in serum, respectively. In addition, the accuracy was verified through enzyme-linked immunosorbent assay (ELISA). Therefore, the proposed LoC-SERS sensing system has great potential for clinical detection of gastric cancer. [ABSTRACT FROM AUTHOR]

Serum analysis is crucial for favourable prognosis of gastric cancer (GC) and for improving patient survival rates. However, it remains a challenge to develop an effective strategy to accurately identify differences in gastric cancer before and after treatment to guide efficacy evaluation. In this study, we combined surface-enhanced Raman scattering (SERS) with principal component analysis (PCA)-two-layer nearest neighbour (TLNN) to propose a promising serum analytical platform for label-free detection of cisplatin-treated GC mice. A microarray chip fabricated from Au nano-hexagon (AuNH) substrates was employed to measure the SERS spectra of the serum of GC mice at different treatment stages, and then a model for recognition of SERS spectra was constructed using a PCA-TLNN algorithm. The results revealed that the microarray chip exhibited superior portability, SERS activity, stability, and uniformity. Through PCA-TLNN, the GC mice at different treatment stages were successfully segregated, and several key spectral features for distinguishing different treatment stages were captured. The established PCA-TLNN model achieved satisfactory results, with an accuracy of over 97.5%, a sensitivity of over 90%, and a specificity of over 96.7%. Label-free serum SERS in combination with multivariate analysis could serve as a potential technique for the clinical diagnosis and staging of treatments. [Display omitted] • The novel microarray chip can realize rapid, sensitive, label-free and high-throughput detection of SERS spectra of serum. • PCA-TLNN successfully differentiated the SERS spectra of serum from cisplatin-treated GC mice at different stages. • The most prominent spectral features for distinguishing different treatment stages. • were captured in PCs loading plots. • PCA-TLNN was superior to traditional multivariate algorithm in accuracy, sensitivity and specificity. [ABSTRACT FROM AUTHOR]

Early and precise diagnosis of lung cancer is critical for a better prognosis. However, it is still a challenge to develop an effective strategy for early precisely diagnose and effective treatments. Here, we designed a label-free and highly accurate classification serum analytical platform for identifying mice with lung cancer. Specifically, the microarray chip integrated with Au nanostars (AuNSs) array was employed to measure the surface-enhanced Raman scattering (SERS) spectra of serum of tumor-bearing mice at different stages, and then a recognition model of SERS spectra was constructed using the principal component analysis (PCA)-representation coefficient-based k-nearest centroid neighbor (RCKNCN) algorithm. The microarray chip can realize rapid, sensitive, and high-throughput detection of SERS spectra of serum. RCKNCN based on the PCA-generated features successfully differentiated the SERS spectra of serum of tumor-bearing mice at different stages with a classification accuracy of 100%. The most prominent spectral features for distinguishing different stages were captured in PCs loading plots. This work not only provides a practical SERS chip for the application of SERS technology in cancer screening, but also provides a new idea for analyzing the feature of serum at the spectral level. [Display omitted] • A rapid, sensitive, label-free, high-throughput SERS microarray chip was developed. • Combining SERS with PCA-RCKNCN successfully differentiated the SERS spectra. • The most prominent spectral features of SERS spectra in PCs loading were captured. • PCA-RCKNCN was superior to traditional multivariate algorithm in accuracy. [ABSTRACT FROM AUTHOR]

Non-small cell lung cancer (NSCLC) is a major histologic category of lung cancer. In this paper, a new type of surface-enhanced Raman scattering (SERS) microfluidic chip proposed for the simultaneous and efficient detection of miR-92a and miR-339-3p, two microRNAs (miRNAs) related to NSCLC. In addition, the method was used to detect miR-92a and miR-339-3p in the serum of NSCLC clinical samples, and the results were consistent with the quantitative real-time polymerase chain reaction (qRT-PCR). In conclusion, this new SERS microfluidic chip is a very promising tool for detecting miRNA expression levels, which can help in the early diagnosis and prognosis of NSCLC. [Display omitted] • SERS effect of the Au-AgNBs array is excellent, which improves the sensitivity of SERS analysis. • The hydrophilic-treated SERS microfluidic chip combined with the hpDNA- functioned Au-AgNBs array eliminates the need for an external driver while improving detection efficiency. • The LOD of the SERS microfluidic chip reaches aM level, and the detection and analysis time is as low as 8 min. • The device can be used for the early diagnosis of non-small cell lung cancer to improve cancer survival rates. In this paper, a novel surface-enhanced Raman scattering (SERS) microfluidic chip is proposed for the simultaneous and efficient detection of miR-92a and miR-339-3p, two microRNAs (miRNAs) related to non-small cell lung cancer (NSCLC). The sample solution can flow along the microchannel into the reaction zone during the assay, driven by the capillary force generated by the comb-like structured channel. A one-step paired hybridization reaction with the corresponding hairpin DNA (hpDNA) on the hpDNA-functioned Au-Ag nanobowl (Au-AgNBs) array takes place when the target strand is present in the sample solution, amplifying the SERS signal. The detection limits of miR-92a and miR-339-3p in serum were 44.36 aM and 63.58 aM, respectively, using this method, with a detection and analysis time of only 8 min. The microfluidic chip showed good specificity, reproducibility, and stability. Finally, the method was used to detect miR-92a and miR-339-3p in the serum of NSCLC clinical samples, and the results were consistent with the quantitative real-time polymerase chain reaction (qRT-PCR). In conclusion, this new SERS microfluidic chip is a very promising tool for detecting miRNA expression levels, which can help in the early diagnosis and prognosis of NSCLC. [ABSTRACT FROM AUTHOR]

MicroRNA (miRNA), as one of the ideal target biomarker analytes, plays an essential role in biological processes; thus, the development of rapidly sensitive detection methods is imperative. Herein, we proposed a pump-free surface-enhanced Raman scatting (SERS) microfluidic chip for the rapid and ultrasensitive detection of miR-106b and miR-196b, laryngeal squamous cell carcinoma (LSCC)-related miRNAs. Ag–Au core-shell nanorods (Ag-AuNRs) were applied to prepare SERS tags by modifying Raman reporters and hairpin DNAs. The capture probes were synthesized by labeling hairpin DNAs onto the magnetic beads (MBs) surface. In the presence of targets, the catalytic hairpin assembly (CHA) reactions between SERS tags and capture probes could be triggered, causing the aggregation of Ag-AuNRs. The tiny magnets installed under the rectangular chamber could magnetically gather the CHA products, leading to the further aggregation of Ag-AuNRs. Thus, this strategy could achieve the double aggregation of Ag-AuNRs, resulting in the significant amplification of the SERS signal. The proposed strategy achieved simultaneous and sensitive detection of miR-106b and miR-196b, with limits of detection low to aM level. The whole detection process could be completed within 5 min. Moreover, this microfluidic chip exhibited excellent reproducibility, stability, and specificity. The high accuracy of this SERS microfluidic chip was proved by practical analysis in LSCC patients' serum. The results demonstrated that SERS could be a promising alternative clinical diagnosis tool and exhibited potential application for the dynamic monitoring of cancer staging. A pump-free SERS microfluidic chip coupling with CHA amplification is fabricated for the ultrasensitive and simultaneous detection of miR-106b and miR-196b. [Display omitted] • To our knowledge, this is the first report demonstrating pump-free SERS microfluidic chip coupling with catalytic hairpin assembly (CHA) reaction for detection of miR-106b and miR-196b simultaneously. • Dual signal amplification composed of CHA-induced powerful cycle amplification and the aggregation effect caused by MBs enables the ultrasensitive detection of miRNA, with the LODs low to aM level. • The entire detection process could be finished less than 5 min. • Excellent uniformity, stability, specificity and reproducibility of this pump-free SERS microfluidic chip are demonstrated. [ABSTRACT FROM AUTHOR]

Accurate quantification of multiple miRNAs biomarkers in body fluid is still a challenge for early screening of cancer. Herein, by catalytic hairpin assembly as a signal amplification strategy, we designed a novel surface-enhanced Raman scattering (SERS)-lateral flow assay (LFA) strip for ultrasensitive detection of miR-21 and miR-196a-5p in non-small cell lung cancer (NSCLC) urine on a single test (T) line. 4-mercaptobenzoic acid or 5,5′-dithiobis-2-nitrobenzoic acid as Raman molecules was labeled and two hairpin DNA sequence was modified gold nanocages (GNCs) were designed as two SERS tags. Through target miRNA-triggered catalytic hairpin assembly (CHA), the double-stranded DNAs (H1–H2 complex) formed by SERS tags and the related hairpin-structured DNA sequence 2 (H2) were immobilized on a single T line of SERS-LFA strip. This generated abundant "hot spots" because of the formation of numerous H1–H2 complex thus facilitated the SERS measurement. Through this method, two kinds of miRNAs were analyzed, resulting in limits of detection of 2.08 pM and 3.31 pM for miR-21 in PBS buffer and human urine, 1.77 pM and 2.18 pM for miR-196a-5p in PBS buffer and human urine. Significantly, the SERS-LFA strip exhibited high specificity and good repeatability toward miRNAs. The whole detection time was only 30 min, which means that the high detection efficiency of the strip. The clinical feasibility of the proposed method was also evaluated by detecting the levels of miR-21 and miR-196a-5p in urine samples from NSCLC patients and healthy subjects. The developed SERS-LFA strip has wide application prospect in biomedical research, drug development and early clinical diagnosis. A novel surface-enhanced Raman scattering-lateral flow assay strip in combination with catalytic hairpin assembly was developed for rapid, sensitive, and simultaneous detection of multiple non-small cell lung cancer-related miRNAs on a single test line. [Display omitted] • A simultaneous detection of multiple cancer biomarkers by catalytic hairpin assembly-based SERS-LFA strip on a single test line with high sensitivity and accuracy is proposed. • GNCs, as a kind of novel nanomaterial, can be prepared on a large scale and has good SERS reinforcement effect. • Catalytic hairpin assembly-based SERS-LFA strip shows favorable performance in clinical test, which can achieve the LODs as low as 3.31 pM (miR-21) and 2.18 pM (miR-196a-5p) in human urine. [ABSTRACT FROM AUTHOR]

Procalcitonion (PCT) have been proved to be disease-related markers of premature rupture of membranes (PROM) in serum of patients. Therefore, the profiling technology of rapid and sensitive is crucial for detecting the level of PCT in human serum, which is of great significance for early diagnosis and treatment of PROM. In this work, the surface-enhanced Raman scattering (SERS) detection platform combined with double antibody sandwich method was used to quantitatively detect PCT in serum of patients with PROM. A highly sensitive, uniform, and reliable SERS substrate was fabricated by assembling Ag nanowires (AgNWs) on the hydrophobic filter paper treated with alkyl ketene dimer (AKD). Then hollow Au nanocages (HAuNCs) with SERS activity were synthesized facilely. The SERS immunoassay system consists of SERS tags and capturing substrate. HAuNCs labled anti-PCT (labeling) were used as SERS tags. Filter paper modified with AgNWs and anti-PCT (coating) was used as capturing substrate. When the SERS immunoassay system were used to directly detect PCT antigen, Raman intensity at different PCT antigen concentrations (1 pg/mL-1 μg/mL) was linearly related to the logarithm of PCT antigen concentration. By establishing a calibration curve within a certain range, it can be concluded that the detection limits of PBS and human serum were as low as 2.86 pg/mL and 3.74 pg/mL respectively. Serum samples from PROM patients were detected by SERS, and the results were consistent with those of the enzyme-linked immunosorbent assay (ELISA). Furthermore, The high reproducibility and homogeneity of SERS immunoassay were confirmed. Above results demonstrated the feasibility and great potential for developing this new SERS immunosensor into a clinical tool for sensitive analysis of biomarkers in human serum. [ABSTRACT FROM AUTHOR]