Fe₃O₄@Ag magnetic nanoparticles for microRNA capture and duplex-specific nuclease signal amplification based SERS detection in cancer cells

Multi-Shell Nanourchin-Integrated Dual Mode Lateral Flow Immunoassay for Sensitive and Rapid Detection of Clinical Cardiac Myosin-Binding Protein C

Cardiac myosin-binding protein C (cMyBP-C) is a novel cardiac marker of acute myocardial infarction (AMI) and acute cardiac injuries (ACI). Construction of point-of-care testing techniques capable of sensing cMyBP-C with high sensitivity and precision is urgently needed. Herein, we synthesized an Au@NGQDs@Au/Ag multi-shell nanoUrchins (MSNUs), and then applied it in a colorimetric/SERS dual-mode immunoassay for detection of cMyBP-C. The MSNUs displayed superior stability, colorimetric brightness, and SERS enhancement ability with an enhanced factor of 5.4 × 109, which were beneficial to improve the detection capability of test strips. The developed MSNU-based test strips can achieve an ultrasensitive immunochromatographic assay of cMyBP-C in both colorimetric and SERS modes with the limits of detection as low as 19.3 and 0.77 pg/mL, respectively. Strikingly, this strip was successfully applied to analyze actual plasma samples with significantly better sensitivity, negative predictive value, and accuracy than commercially available gold test strips. Notably, this method possessed a wide range of application scenarios via combining with a color recognizer application named Color Grab on the smartphone, which can meet various needs of different users. Overall, our MSNU-based test strip as a mobile health monitoring tool shows excellent sensitivity, reproducibility, and rapid detection of the cMyBP-C, which holds great potential for the early clinic diagnosis of AMI and ACI.

Electrochemical immunosensing of tumor markers

The rising incidence and mortality rates of cancer have led to a growing need for precise and prompt early diagnostic approaches to effectively combat this disease. However, traditional methods employed for detecting tumor cells, such as histopathological and immunological techniques, are often associated with complex procedures, high analytical expenses, elevated false positive rates, and a dependence on experienced personnel. Tracking tumor markers is recognized as one of the most effective approaches for early detection and prognosis of cancer. While onco-biomarkers can also be produced in normal circumstances, their concentration is significantly elevated when tumors are present. By monitoring the levels of these markers, healthcare professionals can obtain valuable insights into the presence, progression, and response to treatment of cancer, aiding in timely diagnosis and effective management. This review aims to provide researchers with a comprehensive overview of the recent advancements in tumor markers using electrochemical immunosensors. By highlighting the latest developments in this field, researchers can gain a general understanding of the progress made in the utilization of electrochemical immunosensors for detecting tumor markers. Furthermore, this review also discusses the current limitations associated with electrochemical immunosensors and offers insights into paving the way for further improvements and advancements in this area of research.

Portable fluorescent lateral flow assay for ultrasensitive point-of-care analysis of acute myocardial infarction related microRNA

Point-of-care quantitative analysis of tracing microRNA disease-biomarkers remains a great challenge in the clinical diagnosis. In this paper, we developed a portable fluorescent lateral flow assay for ultrasensitive quantified detection of acute myocardial infarction related microRNAs in bio-samples. SiO2@DQD (bilayer quantum dots assembly with SiO2 core) based fluorescent lateral flow strip was fabricated as the analysis tool. In order to quantify the tracing microRNA in biosamples, a catalytic hairpin assembly and CRISPR/Cas12a cascade amplification method was performed and combined with the fabricated SiO2@DQD lateral flow strip. Thus, our platform gathered double advantages of portability and ultrasensitive quantification. Based on our strips, target myocardial biomarker microRNA-133a can be detected with a detection limit of 0.32 fM, which was almost 1000-fold sensitive compared with previous reported microRNAs-lateral flow strips. Significantly, this portable fluorescent strip can directly detect microRNAs in serum without any pretreatment and PCR amplification steps. When spiked in serum samples, a recovery of 99.65 %-102.38 % can be obtained. Therefore, our method offers a potential tool for ultrasensitive quantification of diseases related microRNA in the point-of-care diseases diagnosis field.

SERS and MRS signals engineered dual-mode aptasensor for simultaneous distinguishment of aflatoxin subtypes

The accurate monitoring of aflatoxin subtypes is vitally important for food safety. Herein, a dual-mode aptasensor with surface-enhanced Raman scattering (SERS) and magnetic relaxation switching (MRS) signals is developed for the detection of aflatoxin B1, B2 and M1 (i.e. AFB1, AFB2 and AFM1). Au-Ag Janus NPs and Au-mushroom NPs are prepared and show intense and non-interfering SERS peaks without the additional modification of Raman molecules, and are utilized as SERS nanotags for the distinguishment of AFB1 and AFB2. Fe3O4@Au NPs functionalized by AFM1 aptamers are applied as MRS nanoprobes for the monitoring of AFM1. Aptamers engineered SERS nanotags and MRS nanoprobes are assembled, and show strong SERS performances and high transverse relaxation time (T2). AFB1, AFB2 and AFM1 induce the separation of SERS nanotags from the assemblies and the dispersion of Fe3O4@Au NPs, resulting in the decrease of SERS signals at 1278 cm-1 and 1000 cm-1 as well as the reduction of T2 values. The dual-mode but three kinds of detection signals don't interfere with each other and exhibit a significant linear relationship with the concentration of targets. This platform provides a high throughput monitoring strategy for the simultaneous analysis of different subtypes of mycotoxin.

SERS-based methods for the detection of genomic biomarkers of cancer

Genomic biomarkers of cancer are based on changes in nucleic acids, which include abnormal expression levels of some miRNAs, point mutations in DNA sequences, and altered levels of DNA methylation. The presence of tumor-related nucleic acids in body fluids (blood, saliva, or urine) makes it possible to achieve a non-invasive early-stage cancer diagnosis. Currently existing techniques for the discovery of nucleic acids require complex, time-consuming, costly assays and have limited multiplexing abilities. Surface-enhanced Raman spectroscopy (SERS) is a vibrational spectroscopy technique that is able to provide molecular specificity combined with trace sensitivity. SERS has gained research attention as a tool for the detection of nucleic acids because of its promising potential: label-free SERS can decrease the complexity of assays currently used with fluorescence-based detection due to the absence of the label, while labeled SERS may outperform the gold standard in terms of the multiplexing ability. The first papers about SERS-based methods for the measurement of genomic biomarkers were written in 2008, and since then, more than 150 papers have been published. The aim of this paper is to review and evaluate the proposed SERS-based methods in terms of their level of development and their potential for liquid biopsy application, as well as to contribute to their further evolution by attracting research attention to the field. This goal will be reached by grouping, on the basis of their experimental protocol, all the published manuscripts on the topic and evaluating each group in terms of its limit of detection and applicability to real body fluids. Thus, the methods are classified according to their working principles into five main groups, including capture-based, displacement-based, sandwich-based, enzyme-assisted, and specialized protocols.

Rapid capture and quantification of food-borne spores based on the double-enhanced Fe3O4@PEI@Ag@PEI core-shell structure SERS sensor

To realize rapid capture and quantification of food-borne spores and prevent their potential harm, Fe3O4@PEI@Ag@PEI core-shell structure nanoparticles were combined with flower-like AgNPs for double enhancement and efficient capture of spores. The developed sensor showed excellent reproducibility and SERS enhancement factor (AEF) is 4.6 × 104. Orthogonal partial least-squares discrimination analysis and linear discriminant analysis accurately identified the three spores (Bacillus subtilis, Bacillus cereus, and Clostridium perfringens), and the qualitative identification accuracy of linear discriminant analysis was 100 %. Efficient enrichment of B. subtilis spores was realized within 5 min, with a detection limit of 3 cfu/mL. Spiked tests revealed that this sensor was effective in detecting spores in milk, orange juice, and water samples, with recovery ratio of 95.2-103.9 % and relative standard deviation of 3.1-7.7 %. Thus, the developed sensor was accurate and reliable, and could achieve rapid identification and quantitative detection of food-borne spores.

Nanozymes: A comprehensive review on emerging applications in cancer diagnosis and therapeutics

Nanozymes, a new class of nanomaterials-based artificial enzymes, have gained huge attraction due to their high operational stability, working efficiency in extreme conditions, and resistance towards protease digestion. Nowadays, they are effectively substituted for natural enzymes for catalysis by closely resembling the active sites found in natural enzymes. Nanozymes can compensate for natural enzymes' drawbacks, such as high cost, poor stability, low yield, and storage challenges. Due to their transforming nature, nanozymes are of utmost importance in the detection and treatment of cancer. They enable precise cancer detection, tailored drug delivery, and catalytic therapy. Through enhanced diagnosis, personalized therapies, and reduced side effects, their adaptability and biocompatibility can transform the management of cancer. The review focuses on metal and metal oxide-based nanozymes, highlighting their catalytic processes, and their applications in the prevention and treatment of cancer. It emphasizes their potential to alter diagnosis and therapy, particularly when it comes to controlling reactive oxygen species (ROS). The article reveals the game-changing importance of nanozymes in the future of cancer care and describes future research objectives, making it a useful resource for researchers, and scientists. Lastly, outlooks for future perspective areas in this rapidly emerging field have been provided in detail.

Molecular beacon decorated silver nanowires for quantitative miRNA detection by a SERS approach

Advantages of biosensors based on surface enhanced Raman scattering (SERS) rely on improved sensitivity and specificity, and suited reproducibility in detecting a target molecule that is localized in close proximity to a SERS-active surface. Herein, a comprehensive study on the realization of a SERS biosensor designed for detecting miRNA-183, a miRNA biomarker that is specific for chronic obstructive pulmonary disease (COPD), is presented. The used strategy exploits a signal-off mechanism by means of a labelled molecular beacon (MB) as the oligonucleotide biorecognition element immobilized on a 2D SERS substrate, based on spot-on silver nanowires (AgNWs) and a multi-well low volume cell. The MB was properly designed by following a dedicated protocol to recognize the chosen miRNA. A limit of detection down to femtomolar concentration (3 × 10-16 M) was achieved and the specificity of the biosensor was proved. Furthermore, the possibility to regenerate the sensing system through a simple procedure is shown: with regeneration by using HCl 1 mM, two detection cycles were performed with a good recovery of the initial MB signal (83%) and a reproducible signal after hybridization.

Optimization of extraction-free protocols for SARS-CoV-2 detection using a commercial rRT-PCR assay

In the ongoing global fight against coronavirus disease 2019 (COVID-19), the sample preparation process for real-time reverse transcription polymerase chain reaction (rRT-PCR) faces challenges due to time-consuming steps, labor-intensive procedures, contamination risks, resource demands, and environmental implications. However, optimized strategies for sample preparation have been poorly investigated, and the combination of RNase inhibitors and Proteinase K has been rarely considered. Hence, we investigated combinations of several extraction-free protocols incorporating heat treatment, sample dilution, and Proteinase K and RNase inhibitors, and validated the effectiveness using 120 SARS-CoV-2 positive and 62 negative clinical samples. Combining sample dilution and heat treatment with Proteinase K and RNase inhibitors addition exhibited the highest sensitivity (84.26%) with a mean increase in cycle threshold (Ct) value of + 3.8. Meanwhile, combined sample dilution and heat treatment exhibited a sensitivity of 79.63%, accounting for a 38% increase compared to heat treatment alone. Our findings highlight that the incorporation of Proteinase K and RNase inhibitors with sample dilution and heat treatment contributed only marginally to the improvement without yielding statistically significant differences. Sample dilution significantly impacts SARS-CoV-2 detection, and sample conditions play a crucial role in the efficiency of extraction-free methods. Our findings may provide insights for streamlining diagnostic testing, enhancing its accessibility, cost-effectiveness, and sustainability.

Deep Learning Assisted Surface-Enhanced Raman Spectroscopy (SERS) for Rapid and Direct Nucleic Acid Amplification and Detection: Toward Enhanced Molecular Diagnostics

Surface-enhanced Raman scattering (SERS) has evolved into a robust analytical technique capable of detecting a variety of biomolecules despite challenges in securing a reliable Raman signal. Conventional SERS-based nucleic acid detection relies on hybridization assays, but reproducibility and signal strength issues have hindered research on directly amplifying nucleic acids on SERS surfaces. This study introduces a deep learning assisted ZnO-Au-SERS-based direct amplification (ZADA) system for rapid, sensitive molecular diagnostics. The system employs a SERS substrate fabricated by depositing gold on uniformly grown ZnO nanorods. These nanorods create hot spots for the amplification of the target nucleic acids directly on the SERS surface, eliminating the need for postamplification hybridization and Raman reporters. The limit of detection of the ZADA system was superior to those of the conventional amplification methods. Clinical validation of the ZADA system with coronavirus disease 2019 (COVID-19) samples from human patients yielded a sensitivity and specificity of 92.31% and 81.25%, respectively. The integration of a deep learning program further enhanced sensitivity and specificity to 100% and reduced SERS analysis time, showcasing the potential of the ZADA system for rapid, label-free disease diagnosis via direct nucleic acid amplification and detection within 20 min.

Magnetically Assisted Immobilization-Free Detection of microRNAs Based on the Signal Amplification of Duplex-Specific Nuclease

The double specific nuclease (DSN)-based methods for microRNAs (miRNAs) detection usually require the immobilization of DNA probes on a solid surface. However, such strategies have the drawbacks of low hybridization and cleavage efficiency caused by steric hindrance effect and high salt concentration on the solid surface. Herein, we proposed an immobilization-free method for miRNA detection on the basic of DSN-assisted signal amplification. The biotin- and fluorophore-labeled probes were captured by streptavidin-modified magnetic beads through streptavidin-biotin interactions, thus producing a poor fluorescence signal. Once the DNA probes were hybridized with target miRNA in solution to form DNA-miRNA duplexes, DNA stands in the duplexes would be selectively digested by DSN. The released target miRNA could initiate the next hybridization/cleavage recycling in the homogeneous solution, finally resulting in the release of numerous fluorophore-labeled fragments. The released fluorophores remained in solution and emitted strong fluorescence after treatment by the streptavidin-modified magnetic beads. The immobilization-free method achieved the assays of miRNA-21 with a detection limit down to 0.01 pM. It was employed to evaluate the expression levels of miRNA-21 in different cancer cells with satisfactory results.

In situ construction of Fe3O4@PDA@Au multi hotspot SERS probe for trace detection of benzodiazepines in serum

The abuse of benzodiazepines is a serious health hazard that can cause damage to the central nervous system.Trace monitoring of benzodiazepines in serum can effectively prevent the damage caused by these drugs. Therefore, in this study, a Fe₃O₄@PDA@Au core-shell satellite nanomaterial SERS(Surface-Enhanced Raman Scattering) probe that integrates magnetic separation techniques and a multi-hotspot structure was synthetized by in situ growth of gold nanoparticles on the surface of PDA(Polymerized dopamine)-coated Fe₃O₄. The size and gap of Au nanoparticles on the surface of the SERS probe can be modulated by regulating the amount of HAuCl₄ to create 3D multi-hotspot structures. The good dispersion and superparamagnetic properties of this SERS probe enable it to fully contact and load the target molecules in the serum, and the applied magnetic field facilitates separation and enrichment.This process increases the molecular density and number of SERS hotspots, thereby enhancing detection sensitivity. Based on the above considerations, this SERS probe can detect traces of eszopiclone and diazepam in serum at concentrations as low as 1 μg/ml with good linearity, offering promising applications in clinical monitoring of drug concentrations in blood.

Recent development of surface-enhanced Raman scattering for biosensing

Surface-Enhanced Raman Scattering (SERS) technology, as a powerful tool to identify molecular species by collecting molecular spectral signals at the single-molecule level, has achieved substantial progresses in the fields of environmental science, medical diagnosis, food safety, and biological analysis. As deepening research is delved into SERS sensing, more and more high-performance or multifunctional SERS substrate materials emerge, which are expected to push Raman sensing into more application fields. Especially in the field of biological analysis, intrinsic and extrinsic SERS sensing schemes have been widely used and explored due to their fast, sensitive and reliable advantages. Herein, recent developments of SERS substrates and their applications in biomolecular detection (SARS-CoV-2 virus, tumor etc.), biological imaging and pesticide detection are summarized. The SERS concepts (including its basic theory and sensing mechanism) and the important strategies (extending from nanomaterials with tunable shapes and nanostructures to surface bio-functionalization by modifying affinity groups or specific biomolecules) for improving SERS biosensing performance are comprehensively discussed. For data analysis and identification, the applications of machine learning methods and software acquisition sources in SERS biosensing and diagnosing are discussed in detail. In conclusion, the challenges and perspectives of SERS biosensing in the future are presented.

A universal ratiometric method for Micro-RNA detection based on the ratio of electrochemical/electrochemiluminescence signal, and toehold-mediated strand displacement amplification

An ultra-selective and reproductive ratiometric platform was introduced based on the ratio of Ru(phen)₃²⁺ electrochemiluminescence (ECL) signal and methylene blue (MB) electrochemistry (EC) signal, which was amplified using a specific and efficient toehold-mediated strand displacement (TMSD). The stable DNA nanoclews (NCs) were efficiently loaded with MB (MB-NCs) as EC signal tags after being synthesized utilizing a simple rolling circle amplification reaction. Besides, Ti₃C₂-based nanocomposite could apply as a superb carrier for both Ru(phen)₃²⁺ and gold nanoparticles (Ti₃C₂-Au-Ru), resulting in a nearly constant ECL internal reference to eliminate the possible interferences. The Ti₃C₂-Au-Ru was attached to the surface of the electrode using Nafion, which exhibited excellent conductivity, and hairpin DNAs (hDNAs) were fixed on AuNPs via an Au-S bond. The designed biosensor was finally applied for miRNA-18a detection as a target model. The TMSD method made it possible to concurrently convert and amplify a single miRNA-18ainput into a large amount of output DNAs with high selectivity. These output DNAs were designed to unfold the stem-locked area of hDNAs. The opened hDNAs then hybridized with the MB-NCs to produce an EC signal. In the proposed biosensing system, by raising the target concentration of miRNA, the EC signal gradually rose, the ECL signal remained nearly constant, and the ratiometric detection method markedly promoted biosensor accuracy. Linear correlations of the ratio value of the EC/ECL with miRNA-18a concentrations between 20 aM and 50 pMwere observed, with the limit of detection of 9 aM. The biosensor was applied to detect miRNA-18a in real serum samples with satisfactory results.

Exosomal MicroRNA Profiling

Exosomes are extracellular vesicles, which have the ability to convey various types of cargo between cells. Lately, a great amount of interest has been paid to exosomal microRNAs (miRNAs), since much evidence has suggested that the sorting of miRNAs into exosomes is not an accidental process. It has been shown that exosomal miRNAs (exo-miRNAs) are implicated in a variety of cellular processes including (but not limited to) cell migration, apoptosis, proliferation, and autophagy. Exosomes can play a role in cardiovascular diseases and can be used as diagnostic biomarkers for several diseases, especially cancer. Tremendous advances in technology have led to the development of various platforms for miRNA profiling. Each platform has its own limitations and strengths that need to be understood in order to use them properly. In the current review, we summarize some exo-miRNAs that are relevant to exo-miRNA profiling studies and describe new methods used for the measurement of miRNA profiles in different human bodily fluids.

DNA-Immobilized Fluorescent Polystyrene Nanoparticles as Probes with Tunable Detection Limits

DNA-immobilized nanoparticle probes show high target specificity; thus, they are employed in various bioengineering and biomedicine applications. When the nanoparticles employed are dye-loaded polymer particles, the resulting probes have the additional benefit of biocompatibility and versatile surface properties. In this study, we construct DNA-immobilized fluorescent polystyrene (PS) nanoparticles through controlled surface reactions. PS nanoparticles with surface carboxyl groups are utilized, and amine-functionalized dye molecules and capture DNAs are covalently immobilized via a one-pot reaction. We show that the surface chemistry employed allows for quantitative control over the number of fluorescent dyes and DNA strands immobilized on the PS nanoparticle surfaces. The nanoparticles thus prepared are then used for DNA detection. The off state of the nanoprobe is achieved by hybridizing quencher-functionalized DNAs (Q-DNAs) to the capture DNAs immobilized on nanoparticle surfaces. Target-DNAs (T-DNAs) are detected by the displacement of the prehybridized Q-DNAs. The nanoprobes show successful detection of T-DNAs with high sequence specificity and long-term stability. They also show excellent detection sensitivity, and the detection limit can be tuned by adjusting the capture DNA-to-dye ratio.

Formation of miRNA Nanoprobes-Conjugation Approaches Leading to the Functionalization

Recently, microRNAs (miRNA) captured the interest as novel diagnostic and prognostic biomarkers, with their potential for early indication of numerous pathologies. Since miRNA is a short, non-coding RNA sequence, the sensitivity and selectivity of their detection remain a cornerstone of scientific research. As such, methods based on nanomaterials have emerged in hopes of developing fast and facile approaches. At the core of the detection method based on nanotechnology lie nanoprobes and other functionalized nanomaterials. Since miRNA sensing and detection are generally rooted in the capture of target miRNA with the complementary sequence of oligonucleotides, the sequence needs to be attached to the nanomaterial with a specific conjugation strategy. As each nanomaterial has its unique properties, and each conjugation approach presents its drawbacks and advantages, this review offers a condensed overview of the conjugation approaches in nanomaterial-based miRNA sensing. Starting with a brief recapitulation of specific properties and characteristics of nanomaterials that can be used as a substrate, the focus is then centered on covalent and non-covalent bonding chemistry, leading to the functionalization of the nanomaterials, which are the most commonly used in miRNA sensing methods.

Iron Oxide-Au Magneto-Plasmonic Heterostructures: Advances in Their Eco-Friendly Synthesis

In recent years, nanotechnologies have attracted considerable interest, especially in the biomedical field. Among the most investigated particles, magnetic based on iron oxides and Au nanoparticles gained huge interest for their magnetic and plasmonic properties, respectively. These nanoparticles are usually produced starting from processes and reagents that can be the cause of potential human health and environmental concerns. For this reason, there is a need to develop simple, green, low-cost, and non-toxic synthesis methods and reagents. This review aims at providing an overview of the most recently developed processes to produce iron oxide magnetic nanoparticles, Au nanoparticles, and their magneto-plasmonic heterostructures using eco-friendly approaches, focusing the attention on the microorganisms and plant-assisted syntheses and showing the first results of the development of magneto-plasmonic heterostructures.

Dual signal magnification for ultrasensitive biosensing based on well-regulated SERS of AuNTs@AuHg and DSN-assisted amplification

AuNTs@AuHg alloy with well-regulated SERS properties was proposed, which displayed wonderful SERS intensity and effective salt resistance. Using miRNA-21 as a model analyte and combining with DSN-assisted amplification, a dual signal amplification strategy for ultrasensitive miRNA biosensing with a low detection limit (0.53 fM) and satisfactory selectivity was designed.

Biosensors and Drug Delivery in Oncotheranostics Using Inorganic Synthetic and Biogenic Magnetic Nanoparticles

Magnetic nanocarriers have attracted attention in translational oncology due to their ability to be employed both for tumor diagnostics and therapy. This review summarizes data on applications of synthetic and biogenic magnetic nanoparticles (MNPs) in oncological theranostics and related areas. The basics of both types of MNPs including synthesis approaches, structure, and physicochemical properties are discussed. The properties of synthetic MNPs and biogenic MNPs are compared with regard to their antitumor therapeutic efficiency, diagnostic potential, biocompatibility, and cellular toxicity. The comparative analysis demonstrates that both synthetic and biogenic MNPs could be efficiently used for cancer theranostics, including biosensorics and drug delivery. At the same time, reduced toxicity of biogenic particles was noted, which makes them advantageous for in vivo applications, such as drug delivery, or MRI imaging of tumors. Adaptability to surface modification based on natural biochemical processes is also noted, as well as good compatibility with tumor cells and proliferation in them. Advances in the bionanotechnology field should lead to the implementation of MNPs in clinical trials.

Comparative Evaluation of Different Surface Coatings of Fe3O4-Based Magnetic Nano Sorbent for Applications in the Nucleic Acids Extraction

Nucleic acid extraction and purification are crucial steps in sample preparation for multiple diagnostic procedures. Routine methodologies of DNA isolation require benchtop equipment (e.g., centrifuges) and labor-intensive steps. Magnetic nanoparticles (MNPs) as solid-phase sorbents could simplify this procedure. A wide range of surface coatings employs various molecular interactions between dsDNA and magnetic nano-sorbents. However, a reliable, comparative evaluation of their performance is complex. In this work, selected Fe3O4 modifications, i.e., polyethyleneimine, gold, silica, and graphene derivatives, were comprehensively evaluated for applications in dsDNA extraction. A family of single batch nanoparticles was compared in terms of morphology (STEM), composition (ICP-MS/MS and elemental analysis), surface coating (UV-Vis, TGA, FTIR), and MNP charge (ζ-potential). ICP-MS/MS was also used to unify MNPs concentration allowing a reliable assessment of individual coatings on DNA extraction. Moreover, studies on adsorption medium (monovalent vs. divalent ions) and extraction buffer composition were carried out. As a result, essential relationships between nanoparticle coatings and DNA adsorption efficiencies have been noticed. Fe3O4@PEI MNPs turned out to be the most efficient nano sorbents. The optimized composition of the extraction buffer (medium containing 0.1 mM EDTA) helped avoid problems with Fe3+ stripping, which improved the validity of the spectroscopic determination of DNA recovery.

Magnetic Nylon 6 Nanocomposites for the Microextraction of Nucleic Acids from Biological Samples

Magnetic Fe3O4 nanoparticles (MNPs) have great potential for nucleic acid separation, detection, and delivery. MNPs are considered a valuable tool in biomedicine due to their cost-effectiveness, stability, easy surface functionalization, and the possibility of the manipulations under a magnetic field. Herein, the synthesis of magnetic nylon 6 nanocomposites (MNPs@Ny6) was investigated. Transmission electron microscopy (TEM) was used for morphology and size analysis. A new method of UV-induced immobilization of oligonucleotides on MNPs@Ny6 for nucleic acid magnetic separation was proposed. MNPs@Ny6 shows a high oligonucleotide binding capacity of 2.2 nmol/mg with 73.3% loading efficiency. The proposed system has been applied to analyze model mixtures of target RNA on the total yeast RNA background. The RNA target isolation efficiency was 60% with high specificity. The bind RNA release was 88.8% in a quantity of 0.16 nmol/mg. The total RNA capture efficiency was 53%. Considering this, the MNPs@Ny6 is an attractive candidate for nucleic acids-specific magnetic isolation.

A new strategy to design label-free electrochemical biosensor for ultrasensitive diagnosis of CYFRA 21-1 as a biomarker for detection of non-small cell lung cancer

Lung cancer is one of the most dangerous cancers with high mortality rate among other cancers therefore, early detection of this cancer is very important. Many studies have been reported in ways of diagnostic lung cancer early. According to reports, one of the most important biomarkers to detect lung cancer is Cytokeratin 19 fragment 21-1 (CYFRA21-1), which is significantly related to non-small cell lung cancer, in particular, squamous cell carcinoma. Thus, finding a new method for the early diagnosis of CYFRA 21-1 (DNA target probe) is essential. In the present report, we design a novel label-free electrochemical DNA-biosensor related to the signal of guanine oxidation. The proposed DNA biosensor is fabricated by a modified glassy carbon electrode (GCE) with reduced-graphene oxide (rGO), poly pyrrole (PPy), silver nanoparticles (AgNPs) and single-strand DNA (ssDNA as capture probe) GCE/rGO/PPy/AgNPs/ssDNA. The differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques are used to verify the hybridization process between capture and target probes. Electrochemical impedance spectroscopy (EIS), energy diffraction X-ray (EDX) and field-emission scanning microscopy (FE-SEM) techniques are applied to the characterization of different modified GCE surfaces as well as X-ray diffraction (XRD) for graphene oxide synthesis. The XRD pattern of the synthesized GO that its diffraction peak appears at 10.2. The applied CV and DPV for the guanine oxidation are determined under optimal conditions. The label-free DNA biosensor showed a great result for the determination of CYFRA21-1 with a wide linear range from two consecutive linear relationships of peak current and CYFRA21-1 concentration were found (1.0 × 10^-14 - 1.0 × 10^-10 M, R² = 0.9936 and 1.0 × 10^-9 - 1.0 × 10^-6 M, R² = 0.9955). Proposed electrochemical biosensor displayed low detection limit (2.4 fM).

Biomedical applications of metallic nanoparticles in cancer: Current status and future perspectives

The current advancements in nanotechnology are as an outcome of the development of engineered nanoparticles. Various metallic nanoparticles have been extensively explored for various biomedical applications. They attract lot of attention in biomedical field due to their significant inert nature, and nanoscale structures, with size similar to many biological molecules. Their intrinsic characteristics which include electronic, optical, physicochemical and, surface plasmon resonance, that can be changed by altering certain particle characteristics such as size, shape, environment, aspect ratio, ease of synthesis and functionalization properties have led to numerous applications in various fields of biomedicine. These include targeted drug delivery, sensing, photothermal and photodynamic therapy, imaging, as well as the modulation of two or three applications. The current article also discusses about the various properties of metallic nanoparticles and their applications in cancer imaging and therapeutics. The associated bottlenecks related to their clinical translation are also discussed.

DNAzyme signal amplification based on Au@Ag core-shell nanorods for highly sensitive SERS sensing miRNA-21

Here, we developed a surface-enhanced Raman scattering (SERS) sensor based on functionalized Au@Ag core-shell nanorods (Au@Ag NRs) and cascade DNAzyme amplifier (CSA) for sensitive and accurate determination of microRNA-21 (miRNA-21). The as-prepared SERS nanoprobes were composed of a thiol-modification hairpin probe (HP2)-functionalized Au@Ag NRs and hairpin DNAzyme (HP1-Dz). Compared with original gold nanorods, the silver shell caused an enhancement of plasmonic properties, resulting in a significant enhancement of Raman signals. In the presence of target miRNAs, the hairpin construction of HP1-Dz changed due to DNA/RNA hybridization; subsequently, the DNAzyme-catalyzed cleaving process changed, and the Raman signals of the SERS nanoprobes gradually "turned off" with time elapse because of the dissociation of the Raman reporter from the surface of Au@Ag NRs. Hence, based on this principle, the proposed SERS sensor exhibited good linearity in the range 0.5 fM to 10 nM for miRNA-21 detection with a detection limit (LOD) of 0.5 fM. The proposed SERS platform has potential application in quantitative and precise detection of miRNA-21 in human serum.

Highly sensitive detection of three protein toxins via SERS-lateral flow immunoassay based on SiO2@Au nanoparticles

We developed surface-enhanced Raman scattering-lateral flow immunoassay (SERS-LFIA) biosensor strips based on SiO₂@Au nanoparticles (NPs) for the specific and highly sensitive detection of ricin, staphylococcal enterotoxin B (SEB), and botulinum neurotoxin type A (BoNT/A). SiO₂@Au NPs were used to prepare SERS tags with useful properties, such as light weight, uniform particle size, good dispersion, and high SERS performance. The detection limit of the SERS-LFIA strips developed herein for ricin, SEB, and BoNT/A was 0.1, 0.05, and 0.1 ng/mL. Their sensitivity was 100-fold higher than that of colloidal gold-LFIA strips, and the same batch of strips had good repeatability. Moreover, the test was completed within 15 min, indicating that the strips are suitable for the rapid and on-site detection of the said toxins. The SERS-LFIA strips based on SiO₂@Au NPs developed herein for the detection of toxins are important to the prevention of bioterrorism attacks.

DNA self-assembled Au nanoparticle clusters on silver nanorod arrays for high-sensitive and multiplex detection of cancer-related biomarkers

To sensitively detect multiple and cross-species disease-related targets from a single biological sample in a quick and reliable manner is of high importance in accurately diagnosing and monitoring diseases. Herein, a surface-enhanced Raman scattering (SERS) sensor based on a functionalized multiple-armed tetrahedral DNA nanostructure (FMTDN) immobilized silver nanorod (AgNR) array substrate and Au nanoparticle (AuNP) SERS tags is constructed to achieve both multiplex detection and enhanced sensitivity using a sandwich strategy. The sensor can achieve single, dual, and triple biomarker detections of three lung cancer-related nucleic acid and protein biomarkers, i.e., miRNA-21, miRNA-486 and carcinoembryonic antigen (CEA) in human serum. The enhanced SERS signals in multiplex detections are due to the DNA self-assembled AuNP clusters on the silver nanorod array during the assay, and the experimentally obtained relative enhancement factor ratios, 150 for AuNP dimers and 840 for AuNP trimers, qualitatively agree with the numerically calculated local electric field enhancements. The proposed FMTDN-functionalized AgNR SERS sensor is capable of multiplex and cross-species detection of nucleic acid and protein biomarkers with improved sensitivity, which has great potential for the screening and clinical diagnosis of cancer in the early stage.

Extension of duplex specific nuclease sensing application with RNA aptamer

Duplex specific nuclease (DSN) that can precisely cleave DNA portion in double-stranded DNA or DNA-RNA hybrid has engrossed immense attention owing to its great potential in emerging bioanalytical applications. Here, we present a novel approach to extend DSN sensing application by coupling RNA aptamer. Specially designed RNA ligand sequences are used to capture the target and simultaneously provide complementary sequences of DNA for DSN aided fluorescent signal enhancement. A clotting enzyme, thrombin, has been used as a model analyte. One RNA aptamer combined with the target molecule can generate fluorescent signals through cleavage of hybridized TaqMan DNA probe (P2) by DSN. The proposed assay has achieved the lowest detection limit of 0.039 pM. The assay has been applied for real-time detection of thrombin release from live cells and other biotic media for early disease diagnosis. The developed method is versatile and can detect various other targets by choosing the relevant aptamer and probe sequences. This method is promising to be applied to medical diagnosis, biosensing, food safety, environmental monitoring, and other fields.

A capillary-driven LoC-SERS device integrated with catalytic hairpin assembly amplification technology for NSCLC-related biomarkers detection

A capillary-driven LoC-SERS device is fabricated for the ultrasensitive detection of NSCLC-related protein biomarkers with catalytic hairpin assembly as the signal amplification strategy.

A review of surface-enhanced Raman spectroscopy in pathological processes

With the continuous growth of the human population and new challenges in the quality of life, it is more important than ever to diagnose diseases and pathologies with high accuracy, sensitivity and in different scenarios from medical implants to the operation room. Although conventional methods of diagnosis revolutionized healthcare, alternative analytical methods are making their way out of academic labs into clinics. In this regard, surface-enhanced Raman spectroscopy (SERS) developed immensely with its capability to achieve single-molecule sensitivity and high-specificity in the last two decades, and now it is well on its way to join the arsenal of physicians. This review discusses how SERS is becoming an essential tool for the clinical investigation of pathologies including inflammation, infections, necrosis/apoptosis, hypoxia, and tumors. We critically discuss the strategies reported so far in nanoparticle assembly, functionalization, non-metallic substrates, colloidal solutions and how these techniques improve SERS characteristics during pathology diagnoses like sensitivity, selectivity, and detection limit. Moreover, it is crucial to introduce the most recent developments and future perspectives of SERS as a biomedical analytical method. We finally discuss the challenges that remain as bottlenecks for a routine SERS implementation in the medical room from in vitro to in vivo applications. The review showcases the adaptability and versatility of SERS to resolve pathological processes by covering various experimental and analytical methods and the specific spectral features and analysis results achieved by these methods.

Three-dimensional nanorod array for label-free surface-enhanced Raman spectroscopy analysis of microRNA pneumoconiosis biomarkers

Novel approaches are required to overcome the challenges associated with conventional microRNA (miRNA) detection methods and realize the early diagnosis of diseases. This work describes a novel label-free surface-enhanced Raman spectroscopy (SERS) method for the detection of the miRNA biomarkers for pneumoconiosis on a three-dimensional Au-coated ZnO nanorod array (Au-ZnO NRA). The Au-ZnO NRA substrate, which was fabricated via a modified seeding method combined with ion sputtering, provided a high enhancement factor and good spatial uniformity of the signal. With the Au-ZnO NRA, the SERS spectra of miRNAs were obtained in 30 s without labeling at room temperature. Density functional theory calculations were performed to understand the structural fingerprints of the miRNAs. Principal component analysis was carried out to identify the pneumoconiosis biomarkers based on their fingerprint SERS signals. Dual-logarithm linear relationships between the SERS intensity and the miRNA concentration were proposed for quantitative analysis. The label-free SERS method has limits of detection on the femtomolar level, which is much lower than the concentrations of the miRNA biomarkers for pneumoconiosis in lung fibroblasts.

Eukaryotic Cell Capture by Amplified Magnetic in situ Hybridization Using Yeast as a Model

A non-destructive approach based on magnetic in situ hybridization (MISH) and hybridization chain reaction (HCR) for the specific capture of eukaryotic cells has been developed. As a prerequisite, a HCR-MISH procedure initially used for tracking bacterial cells was here adapted for the first time to target eukaryotic cells using a universal eukaryotic probe, Euk-516R. Following labeling with superparamagnetic nanoparticles, cells from the model eukaryotic microorganism Saccharomyces cerevisiae were hybridized and isolated on a micro-magnet array. In addition, the eukaryotic cells were successfully targeted in an artificial mixture comprising bacterial cells, thus providing evidence that HCR-MISH is a promising technology to use for specific microeukaryote capture in complex microbial communities allowing their further morphological characterization. This new study opens great opportunities in ecological sciences, thus allowing the detection of specific cells in more complex cellular mixtures in the near future.

Highly sensitive and portable mRNA detection platform for early cancer detection

Pancreatic cancer, at unresectable advanced stages, presents poor prognoses, which could be prevented by early pancreatic cancer diagnosis methods. Recently, a promising early-stage pancreatic cancer biomarker, extracellular vesicles (EVs) related glypican-1 (GPC1) mRNA, is found to overexpress in pancreatic cancer cells. Current mRNA detection methods usually require expensive machinery, strict preservation environments, and time-consuming processes to guarantee detection sensitivity, specificity, and stability. Herein, we propose a novel two-step amplification method (CHAGE) via the target triggered Catalytic Hairpin Assembly strategy combined with Gold-Enhanced point-of-care-testing (POCT) technology for sensitive visual detection of pancreatic cancer biomarker. First, utilizing the catalyzed hairpin DNA circuit, low expression of the GPC1 mRNA was changed into amplification product 1 (AP1, a DNA duplex) as the next detection targets of the paper strips. Second, the AP1 was loaded onto a lateral flow assay and captured with the gold signal nanoparticles to visualize results. Finally, the detected results can be further enhanced by depositing gold to re-enlarge the sizes of gold nanoparticles in detection zones. As a result, the CHAGE methodology lowers the detection limit of mRNA to 100 fM and provides results within 2 h at 37 °C. Furthermore, we demonstrate the successful application in discriminating pancreatic cancer cells by analyzing EVs' GPC1 mRNA expression levels. Hence, the CHAGE methodology proposed here provides a rapid and convenient POCT platform for sensitive detection of mRNAs through unique probes designs (COVID, HPV, etc.).

Highly Sensitive and Reliable microRNA Detection with a Recyclable Microfluidic Device and an Easily Assembled SERS Substrate

Surface-enhanced Raman spectroscopy (SERS) detection in microfluidics is an interesting topic because of its high sensitivity, miniaturization, and ability to perform online detection. However, the difficulties in generating SERS-based microfluidic devices with uniform signal reproducibility and high sensitivity have hindered their widespread application. In addition, the recyclability of the SERS-based microfluidic devices can contribute to their broad commercialization, but the possible contamination in the detection area and cumbersome cleaning procedures remain a challenge. In this study, we describe a repeatable SERS-based microfluidic device comprising a disposable SERS substrate and a reusable microfluidic channel. The microfluidic channel was prepared via mechanical processing, and the SERS substrate was fabricated by nanoimprint lithography and electrodeposition. The SERS substrate and microfluidic channel can be attached easily because they were assembled using screws. The SERS substrate achieved an excellent SERS enhancement factor greater than 10⁸ over a large sample area, signal uniformity, and substrate-to-substrate reproducibility. This guaranteed reliable and sensitive signals in every experiment. Furthermore, the disposable SERS substrate contributed exact detection of target molecules. Finally, their practical application was demonstrated with the repeated use of the microfluidic device by detecting a specific micro-RNA, (miR-34a) at a concentration as low as 5 fM.

Multifunctional nanoparticles as optical biosensing probe for breast cancer detection: A review

Optical biosensors show attractive performance in medical sensing in the event of using different nanoparticles in their design. Owing to their unique optical characteristics and biological compatibility, gold nanoparticles (GNPs), silver nanoparticles (AgNPs), bimetallic nanoparticles and magnetic nanoparticles have been broadly implemented in making sensing tools. The functionalization of these nanoparticles with different components provides an excellent opportunity to assemble selective and sensitive sensing materials to detect various biological molecules related to breast cancer. This review summarizes the recent application of optical biosensing devices based on nanomaterials and discusses their pros and cons to improve breast cancer detection in real samples. In particular, the main constituent elements of these optical biosensors including recognition and transducer elements, types of applied nanostructures, analytical sensing procedures, sensor detection ranges and limit of detection (LOD), are expressed in detail.

Automatic and sensitive detection of West Nile virus non-structural protein 1 with a portable SERS-LFIA detector

A portable surface-enhanced Raman scattering (SERS)-lateral flow immunoassay (LFIA) detector has been developed for the automatic and highly sensitive detection of West Nile virus (WNV) non-structural protein 1 (NS1) and actual WNV samples. Au@Ag nanoparticles (Au@Ag NPs) labeled with double-layer Raman molecules were used as SERS tags to prepare WNV-specific SERS-LFIA strips. On this platform, the WNV-specific antigen NS1 protein was quantitatively and sensitively detected. The detection limit for the WNV NS1 protein was 0.1 ng/mL, which was 100-fold more sensitive than visual signals. The detection limit for inactivated WNV virions was 0.2 × 10² copies/μL. The sensitivity of the SERS-LFIA detector was comparable to that of the fluorescence quantitative reverse transcription-polymerase chain reaction assay. The prepared SERS-LFIA strips exhibited high sensitivity and good specificity for WNV. Thus, the strips developed herein have clinical application value. Moreover, the portable SERS-LFIA detector enabled automatic and rapid detection of the SERS-LFIA strips. The platform established herein is expected to make a substantial contribution to the diagnosis and control of outbreaks of emerging infectious diseases, including WNV.

Recent progress of SERS optical nanosensors for miRNA analysis

This review focuses on emerging applications of surface-enhanced Raman spectroscopy (SERS) optical nanosensors for miRNA analysis, in which the key enhancement factors of the SERS signal, i.e. SERS-active substrates, SERS nanoprobes and nano-assembly strategy, are emphasized. This article includes many nanomaterials for miRNA analysis by the SERS technique. We summarize these reported nanomaterials mainly according to their function in the miRNA assay biosensor. We also briefly summarize the research progress of these nanomaterials in SERS detection of intracellular miRNA. Finally, we discussed the prospect and limitations of SERS nanosensors for analyzing miRNA.

Preparation of Fe3O4-Ag Nanocomposites with Silver Petals for SERS Application

The formation of silver nanopetal-Fe3O4 poly-nanocrystals assemblies and the use of the resulting hetero-nanostructures as active substrates for Surface Enhanced Raman Spectroscopy (SERS) application are here reported. In practice, about 180 nm sized polyol-made Fe3O4 spheres, constituted by 10 nm sized crystals, were functionalized by (3-aminopropyl)triethoxysilane (APTES) to become positively charged, which can then electrostatically interact with negatively charged silver seeds. Silver petals were formed by seed-mediated growth in presence of Ag+ cations and self-assembly, using L-ascorbic acid (L-AA) and polyvinyl pyrrolidone (PVP) as mid-reducing and stabilizing agents, respectively. The resulting plasmonic structure provides a rough surface with plenty of hot spots able to locally enhance significantly any applied electrical field. Additionally, they exhibited a high enough saturation magnetization with Ms = 9.7 emu g-1 to be reversibly collected by an external magnetic field, which shortened the detection time. The plasmonic property makes the engineered Fe3O4-Ag architectures particularly valuable for magnetically assisted ultra-sensitive SERS sensing. This was unambiguously established through the successful detection, in water, of traces, (down to 10-10 M) of Rhodamine 6G (R6G), at room temperature.

Progress in the research of nanomaterial-based exosome bioanalysis and exosome-based nanomaterials tumor therapy

Exosomes and their internal components have been proven to play critical roles in cell-cell interactions and intrinsic cellular regulations, showing promising prospects in both biomedical and clinical fields. Although conventional methods have so far been utilized to great effect, accurate bioanalysis remains a major challenge. In recent years, the fast-paced development of nanomaterials with unique physiochemical properties has led to a boom in the potential bioapplications of such materials. In particular, the application of nanomaterials in exosome bioanalysis provides a great opportunity to overcome the current challenges and limitations of conventional methods. A timely review of the research progress in this field is thus of great significance to the continued development of new methods. This review outlines the properties and potential uses of exosomes, and discusses the conventional methods currently used for their analysis. We then focus on exploring the current state of the art regarding the use of nanomaterials for the isolation, detection and even the subsequent profiling of exosomes. The main methods are based on principles including fluorescence, surface-enhanced Raman spectroscopy, colorimetry, electrochemistry, and surface plasmon resonance. Additionally, research on exosome-based nanomaterials tumor therapy is also promising from a clinical perspective, so the research progress in this branch is also summarized. Finally, we look at ways in which the field might develop in the future.

Recent Advances in Surface-Enhanced Raman Scattering Magnetic Plasmonic Particles for Bioapplications

The surface-enhanced Raman scattering (SERS) technique, that uses magnetic plasmonic particles (MPPs), is an advanced SERS detection platform owing to the synergetic effects of the particles’ magnetic and plasmonic properties. As well as being an ultrasensitive and reliable SERS material, MPPs perform various functions, such as aiding in separation, drug delivery, and acting as a therapeutic material. This literature discusses the structure and multifunctionality of MPPs, which has enabled the novel application of MPPs to various biological fields.

An Overview on Recent Progress of Metal Oxide/Graphene/CNTs-Based Nanobiosensors

Nanobiosensors are convenient, practical, and sensitive analyzers that detect chemical and biological agents and convert the results into meaningful data between a biologically active molecule and a recognition element immobilized on the surface of the signal transducer by a physicochemical detector. Due to their fast, accurate and reliable operating characteristics, nanobiosensors are widely used in clinical and nonclinical applications, bedside testing, medical textile industry, environmental monitoring, food safety, etc. They play an important role in such critical applications. Therefore, the design of the biosensing interface is essential in determining the performance of the nanobiosensor. The unique chemical and physical properties of nanomaterials have paved the way for new and improved sensing devices in biosensors. The growing demand for devices with improved sensing and selectivity capability, short response time, lower limit of detection, and low cost causes novel investigations on nanobiomaterials to be used as biosensor scaffolds. Among all other nanomaterials, studies on developing nanobiosensors based on metal oxide nanostructures, graphene and its derivatives, carbon nanotubes, and the widespread use of these nanomaterials as a hybrid structure have recently attracted attention. Nanohybrid structures created by combining these nanostructures will directly meet the future biosensors' needs with their high electrocatalytic activities. This review addressed the recent developments on these nanomaterials and their derivatives, and their use as biosensor scaffolds. We reviewed these popular nanomaterials by evaluating them with comparative studies, tables, and charts.

Light-Interacting iron-based nanomaterials for localized cancer detection and treatment

To improve the prognosis of cancer patients, methods of local cancer detection and treatment could be implemented. For that, iron-based nanomaterials (IBN) are particularly well-suited due to their biocompatibility and the various ways in which they can specifically target a tumor, i.e. through passive, active or magnetic targeting. Furthermore, when it is needed, IBN can be associated with well-known fluorescent compounds, such as dyes, clinically approved ICG, fluorescent proteins, or quantum dots. They may also be excited and detected using well-established optical methods, relying on scattering or fluorescent mechanisms, depending on whether IBN are associated with a fluorescent compound or not. Systems combining IBN with optical methods are diverse, thus enabling tumor detection in various ways. In addition, these systems provide a wealth of information, which is inaccessible with more standard diagnostic tools, such as single tumor cell detection, in particular by combining IBN with near-field scanning optical microscopy, dark-field microscopy, confocal microscopy or super-resolution microscopy, or the highlighting of certain dynamic phenomena such as the diffusion of a fluorescent compound in an organism, e.g. using fluorescence lifetime imaging, fluorescence resonance energy transfer, fluorescence anisotropy, or fluorescence tomography. Furthermore, they can in some cases be complemented by a therapeutic approach to destroy tumors, e.g. when the fluorescent compound is a drug, or when a technique such as photo-thermal or photodynamic therapy is employed. This review brings forward the idea that iron-based nanomaterials may be associated with various optical techniques to form a commercially available toolbox, which can serve to locally detect or treat cancer with a better efficacy than more standard medical approaches. STATEMENT OF SIGNIFICANCE: New tools should be developed to improve cancer treatment outcome. For that, two closely-related aspects deserve to be considered, i.e. early tumor detection and local tumor treatment. Here, I present various types of iron-based nanomaterials, which can achieve this double objective when they interact with a beam of light under specific and accurately chosen conditions. Indeed, these materials are biocompatible and can be used/combined with most standard microscopic/optical methods. Thus, these systems enable on the one hand tumor cell detection with a high sensitivity, i.e. down to single tumor cell level, and on the other hand tumor destruction through various mechanisms in a controlled and localized manner by deciding whether or not to apply a beam of light and by having these nanomaterials specifically target tumor cells.

Attomolar-Level Ultrasensitive and Multiplex microRNA Detection Enabled by a Nanomaterial Locally Assembled Microfluidic Biochip for Cancer Diagnosis

Non-invasive early diagnosis is of great significance in disease pathologic development and subsequent medical treatments, and microRNA (miRNA) detection has attracted critical attention in early cancer screening and diagnosis. High-throughput, sensitive, economic, and fast miRNA sensing platforms are necessary to realize the low-concentration miRNA detection in clinical diagnosis and biological studies. Here, we developed an attomolar-level ultrasensitive, rapid, and multiple-miRNA simultaneous detection platform enabled by nanomaterial locally assembled microfluidic biochips. This platform presents a large linear detection regime of 1 aM-10 nM, an ultralow detection limit of 0.146 aM with no amplification, a short detection time of 35 min with multiplex miRNA sensing capability, and a small sample volume consumption of 2 μL. The detection results of five miRNAs in real samples from breast cancer patients and healthy humans indicate its excellent capacity for practical applications in early cancer diagnosis. The proposed ultrasensitive, rapid, and multiple-miRNA detection microfluidic biochip platform is a universal miRNA detection approach and an important and valuable tool in early cancer screening and diagnosis as well as biological studies.