Metal-Graphene Hybrid Terahertz Metasurfaces for Circulating Tumor DNA Detection Based on Dual Signal Amplification.

Terahertz (THz) spectroscopy has impressive capability for label-free biosensing, but its utility in clinical laboratories is rarely reported due to often unsatisfactory detection performances. Here, we fabricated metal-graphene hybrid THz metasurfaces (MSs) for the sensitive and enzyme-free detection of circulating tumor DNA (ctDNA) in pancreatic cancer plasma samples. The feasibility and mechanism of the enhanced effects of a graphene bridge across the MS and amplified by gold nanoparticles (AuNPs) were investigated experimentally and theoretically. The AuNPs serve to boost charge injection in the graphene film and result in producing a remarkable change in the graded transmissivity index to THz radiation of the MS resonators. Assay design utilizes this feature and a cascade hybridization chain reaction initiated on magnetic beads in the presence of target ctDNA to achieve dual signal amplification (chemical and optical). In addition to demonstrating subfemtomolar detection sensitivity and single-nucleotide mismatch selectivity, the proposed method showed remarkable capability to discriminate between pancreatic cancer patients and healthy individuals by recognizing and quantifying targeted ctDNAs. The introduction of graphene to the metasurface produces an improved sensitivity of 2 orders of magnitude for ctDNA detection. This is the first study to report the combined application of graphene and AuNPs in biosensing by THz spectroscopic resonators and provides a combined identification scheme to detect and discriminate different biological analytes, including nucleic acids, proteins, and various biomarkers.

DR10627, a Novel Dual Glucagon­like Peptide­1 and Gastric Inhibitory Polypeptide Receptor Agonist for the Treatment of Obesity and Type 2 Diabetes Mellitus.

Introduction: Diabetes and obesity are momentous risk factors threatening people's lives and health. Currently available incretin analogue glucagon-like peptide 1 (GLP-1) possesses huge hypoglycemic effect with the unsatisfactory effect of weight loss. Co-agonists targeting GLP-1R plus glucagon receptor (GCGR) or gastric inhibitory polypeptide receptor (GIPR) show synergistic benefits in glycaemic control and weight loss. Here, we describe a novel dual GIP and GLP-1 receptor agonist, DR10627, and performed a preclinical assessment of it. Methods: The agonistic ability of DR10627 was indirectly assessed by inducing cAMP accumulation in Chinese hamster ovary (CHO) cells transfected with GLP-1R or GIPR in vitro. The plasma pharmacokinetics of DR10627 were analysed in cynomolgus monkeys. The OGTTs were performed in Sprague­Dawley (SD) rats. The glucose lowering effects were evaluated by repeated administration of DR10627 in diabetic (db/db) mice for 4 weeks. The effects of anti-obesity and improving metabolism of DR10627 were evaluated by repeated administration of DR10627 in diet-induced obesity (DIO) mice for 57 days. Results: DR10627 had the capacity to activate both GLP-1R and GIPR in vitro. The terminal half-life of DR10627 was found to be approximately 4.19-5.8 h in cynomolgus monkeys. DR10627 had a great improvement in oral glucose tolerance in SD rats. Moreover, DR10627 had a potent glucose-lowering effect in db/db mice, and the hypoglycemic effect of 18 nmol/kg DR10627 was better than that of 50 nmol/kg liraglutide. In addition, 10 and 30 nmol/kg DR10627 possessed the ability of potentiating the weight-loss, lipid-lowing efficacy and improving metabolism to a greater extent than 80 nmol/kg liraglutide. Conclusion: Preclinical assessment demonstrated that administration of DR10627 resulted in glucose lowering in SD rats and db/db mice, and substantial body weight reduction and metabolism improvement in DIO mice. DR10627 is a promising agent deserving further investigation for the treatment of type 2 diabetes and obesity.

Rapid and sensitive detection of Staphylococcus aureus using a THz metamaterial biosensor based on aptamer-functionalized Fe3O4@Au nanocomposites.

Staphylococcus aureus (S. aureus) poses a serious threat to global public health, necessitating the establishment of rapid and simple tools for its accurate identification. Herein, we developed a terahertz (THz) metamaterial biosensor based on aptamer-functionalized Fe3O4@Au nanocomposites for quantitative S. aureus assays in different clinical samples. Fe3O4@Au@Cys@Apt has the dual advantages of magnetism and a high refractive index in the THz range and was used to rapidly separate and enrich target bacteria in a complex environmental solution. Furthermore, conjugation to the nanocomposites significantly increased the resonance frequency shift of the THz metamaterial after target loading. Our results showed that the shifts in the metamaterial resonance frequency were linearly related to S. aureus concentrations ranging from 1.0 × 103 to 1.0 × 107 CFU/mL, with a detection limit of 4.78 × 102 CFU/mL. The biosensor was further applied to S. aureus detection in spiked human urine and blood with satisfactory recoveries (82.4-109.6%). Our approach also demonstrated strong concordance with traditional plate counting (R2 = 0.99306) while significantly lowering the analysis time from 24 h to <1 h. In conclusion, the proposed biosensor can not only perform culture-free and extraction-free detection of target bacteria but can also be easily extended to the determination of other pathogenic bacteria, rendering it suitable for various bacteria-related disease diagnoses.

Rapid and noninvasive cell assay by microfluidic-integrated intracavity evanescent field absorption in a fiber ring laser.

BACKGROUND: Highly sensitive and rapid detection of cell concentration and interfacial molecular events is of great value for biological, biomedical, and chemical research. Most traditional biosensors require large sample volumes and complicated functional modifications of the surface. It is of great significance to develop label-free biosensor platforms with minimal sample consumption for studying cell concentration changes and interfacial molecular events without labor-intensive procedures. RESULTS: Here, a fiber-optic biosensor based on intracavity evanescent field absorption sensing is designed for sensitive and label-free cell assays for the first time. The interaction between the cells and the evanescent field is enhanced by introducing microfluidic-integrated intracavity absorption in a fiber ring laser. This strategy extends the range of targeted analytes to include quantification of a large number of targets on a surface and improves the detection sensitivity of the fiber-optic biosensor. The level of sensing resolution could be improved from 10-4 RIU to 10-7 RIU using this strategy. The stem cells were studied over a wide concentration range (from 500 to 1.2 × 105 cells/ml) and were measured sequentially. By measuring the output power of the intracavity absorption sensing system, the cell concentration can be directly determined in a label-free manner. The results show that dozens of stem cells can be sensitively detected with a sample consumption of 72 µL. The response was fast (15 s) with a low temperature cross-sensitivity of 0.031 cells·ml-1/°C. SIGNIFICANCE: The proposed method suggests its capacity for true label-free and noninvasive cell assays with a low limit of detection and small sample consumption. This has the potential to be used as a universal tool for quantitative and qualitative characterization of various cells and other biochemical analytes.

A Novel Optical Fiber Terahertz Biosensor Based on Anti-Resonance for The Rapid and Nondestructive Detection of Tumor Cells.

The sensitive and accurate detection of tumor cells is essential for successful cancer therapy and improving cancer survival rates. However, current tumor cell detection technologies have some limitations for clinical applications due to their complexity, low specificity, and high cost. Herein, we describe the design of a terahertz anti-resonance hollow core fiber (THz AR-HCF) biosensor that can be used for tumor cell detection. Through simulation and experimental comparisons, the low-loss property of the THz AR-HCF was verified, and the most suitable fiber out of multiple THz AR-HCFs was selected for biosensing applications. By measuring different cell numbers and different types of tumor cells, a good linear relationship between THz transmittance and the numbers of cells between 10 and 106 was found. Meanwhile, different types of tumor cells can be distinguished by comparing THz transmission spectra, indicating that the biosensor has high sensitivity and specificity for tumor cell detection. The biosensor only required a small amount of sample (as low as 100 µL), and it enables label-free and nondestructive quantitative detection. Our flow cytometry results showed that the cell viability was as high as 98.5 ± 0.26% after the whole assay process, and there was no statistically significant difference compared with the negative control. This study demonstrates that the proposed THz AR-HCF biosensor has great potential for the highly sensitive, label-free, and nondestructive detection of circulating tumor cells in clinical samples.

Thermus thermophilus Argonaute-Based Isothermal Amplification Assay for Ultrasensitive and Specific RNA Detection.

Recent advances in prokaryotic Argonaute proteins (pAgos) as potential genome-editing tools have provided new insights into the development of pAgos-based nucleic acid detection platforms. However, pAgos-based isothermal detection remains challenging. Here, we report a true isothermal amplification strategy, termed Thermus thermophilus Argonaute-based thermostable exponential amplification reaction (TtAgoEAR), to detect RNA with ultrasensitivity and single-nucleotide resolution at a constant temperature of 66 °C. We demonstrate the reliable detection of lncRNA, mRNA, and virus RNA with attomolar sensitivity and that TtAgoEAR can be applied to detect RNA targets in in cell lines, saliva, and tissues. We utilize this assay to distinguish pancreatic cancer cells carrying the mutation from wild-type cells with as little as 2 ng of RNA material. We also show that TtAgoEAR is easily adaptable to a lateral-flow-based readout. These results demonstrate that TtAgoEAR has great potential to facilitate reliable and easy RNA detection in point-of-care diagnosis and field analysis.

Graphene-enhanced hybrid terahertz metasurface sensor for ultrasensitive nortriptyline sensing and detection.

Graphene is a two-dimensional material with unique physical and chemical properties, whose excellent biocompatibility has also attracted widespread attention in the field of biosensing and medical detection. Graphene provides a novel solution for dramatically improving the sensitivity of terahertz metasurface sensors, since the electrical conductivity can be modified by contact with biomolecules. In this paper, a metal-graphene hybrid metasurface is proposed and demonstrated for high-sensitive nortriptyline sensing based on the plasmon-induced transparency (PIT) resonances. The π-π stacks between nortriptyline and graphene lead to an increase in the Fermi level of graphene and a decrease in the conductivity, thus enhancing the PIT resonance. Experimental results show that the peak-to-peak amplitude magnitude of the PIT window is enhanced up to 3.4-fold with 1 ng nortriptyline analyte, and the minimum detection limit is extended down to 0.1 ng. But no significant change is observed from the samples without graphene as a comparative experiment, which demonstrates that the presence of graphene greatly enhances the bonding to the drug molecules and improves the sensing sensitivity. This metasurface sensor has the advantages of high sensitivity, fast detection speed, label-free and steady properties, which has potential applications in the fields of trace molecular sensing and disease diagnosis.

Flexible Terahertz Metamaterial Biosensor for Ultra-Sensitive Detection of Hepatitis B Viral DNA Based on the Metal-Enhanced Sandwich Assay.

The high sensitivity and specificity of terahertz (THz) biosensing are both promising and challenging in DNA sample detection. This study produced and refined a flexible THz MM biosensor for ultrasensitive detection of HBV in clinical serum samples based on a gold magnetic nanoparticle-mediated rolling circle amplification (GMNPs@RCA) sandwich assay under isothermal conditions. Typically, solid-phase RCA reactions mediated by circular padlock probes (PLPs) are triggered under isothermal conditions in the presence of HBV DNA, resulting in long single-stranded DNA (ssDNA) with high fidelity and specificity. Then, the resultant ssDNA was conjugated with detection probes (DPs) immobilized on gold nanoparticles (DP@AuNPs) to form GMNPs-RCA-AuNPs sandwich complexes. The HBV DNA concentrations were quantified by introducing GMNPs-RCA-AuNPs complexes into the metasurface of a flexible THz metamaterial-based biosensor chip and resulting in a red shift of the resonance peak of the THz metamaterials. This biosensor can lead to highly specific and sensitive detection with one-base mismatch discrimination and a limit of detection (LOD) down to 1.27E + 02 IU/ml of HBV DNA from clinical serum samples. The HBV DNA concentration was linearly correlated with the frequency shift of the THz metamaterials within the range of 1.27E + 02∼1.27E + 07 IU/ml, illustrating the applicability and accuracy of our assay in real clinical samples. This strategy constitutes a promising THz sensing method to identify virus DNA. In the future, it is hoped it can assist with pathogen identification and clinical diagnosis.

Evaluation of classification ability of logistic regression model on SERS data of miRNAs.

Logistic regression (LR) is a supervised multiple linear regression model, which uses linear weighted calculation for input to obtain weight coefficients of model. The surface enhanced Raman spectroscopy (SERS) technology greatly enhances the Raman signal of analyte. LR model was used to analyze the data of seven types of pancreatic cancer-related miRNAs obtained from commercial SERS substrate. The classification ability of the model on such data was observed under the configurations of different key parameters (classification mode, regularization method and loss function optimization way), and the effect of the two types of data formats were also evaluated. The results showed that though LR model used to classify this data did not perform well as expected, miRNA-191 and miRNA-4306 still had high recalls (sensitivity), which laid a theoretical foundation for the purpose of using LR model to identify these two miRNAs to jointly diagnose of pancreatic cancer at miRNA level.

THz-ATR Spectroscopy Integrated with Species Recognition Based on Multi-Classifier Voting for Automated Clinical Microbial Identification.

The demand for rapid and accurate identification of microorganisms is growing due to considerable importance in all areas related to public health and safety. Here, we demonstrate a rapid and label-free strategy for the identification of microorganisms by integrating terahertz-attenuated total reflection (THz-ATR) spectroscopy with an automated recognition method based on multi-classifier voting. Our results show that 13 standard microbial strains can be classified into three different groups of microorganisms (Gram-positive bacteria, Gram-negative bacteria, and fungi) by THz-ATR spectroscopy. To detect clinical microbial strains with better differentiation that accounts for their greater sample heterogeneity, an automated recognition algorithm is proposed based on multi-classifier voting. It uses three types of machine learning classifiers to identify five different groups of clinical microbial strains. The results demonstrate that common microorganisms, once time-consuming to distinguish by traditional microbial identification methods, can be rapidly and accurately recognized using THz-ATR spectra in minutes. The proposed automatic recognition method is optimized by a spectroscopic feature selection algorithm designed to identify the optimal diagnostic indicator, and the combination of different machine learning classifiers with a voting scheme. The total diagnostic accuracy reaches 80.77% (as high as 99.6% for Enterococcus faecalis) for 1123 isolates from clinical samples of sputum, blood, urine, and feces. This strategy demonstrates that THz spectroscopy integrated with an automatic recognition method based on multi-classifier voting significantly improves the accuracy of spectral analysis, thereby presenting a new method for true label-free identification of clinical microorganisms with high efficiency.

One-step isothermal amplification strategy for microRNA specific and ultrasensitive detection based on nicking-assisted entropy-driven DNA circuit triggered exponential amplification reaction.

Sensitive and specific detection of microRNAs (miRNAs) is of critical significance for early diagnosis of cancers such as pancreatic cancer with atypical initial symptoms and high mortality. Despite exponential amplification reaction (EXPAR) is an attractive isothermal amplification method for detecting miRNAs, it faces the problems of the dependence difference and low specificity. To address such challenges, herein, a nicking-assisted entropy-driven DNA circuit triggered exponential amplification reaction (NAED-EXPAR) was firstly employed for ultrasensitive and specific detection of miRNA in "one-pot" manner at constant temperature. Nicking-assisted entropy-driven DNA circuit can specifically recognize the target miRNA, leading to continuous disassembly of DNA substrates via intramolecular toehold-mediated branch migration. During the reaction, the catalytic circuit can consume excess fuel DNA strands to produce a large number of primers. Then the newly formed primers can trigger EXPAR for highly efficient signal amplification. Mechanism analysis shows that the amplification efficiency of NAED-EXPAR is superior than that of single EXPAR. For miR-21, the detection limit of NAED-EXPAR can reach 100 aM, which is at least five orders of magnitude higher than the standard EXPAR that directly uses the target as primer. NAED-EXPAR shows improved specificity for identifying single nucleotide variations and enables sensitive and accurate analysis of miR-21 in human cancer cell lines. This method is expected to offer a new approach for the reliable quantification of miRNAs in complex biological matrices and provide valuable information for early cancer diagnosis.

TNF-α Antagonizes the Effect of Leptin on Insulin Secretion through FOXO1-Dependent Transcriptional Suppression of LepRb in INS-1 Cells.

Proinflammatory cytokines play a causal role in the development of hyperinsulinemia and T2MD. FOXO1, a transcription factor which is known to enhance proinflammation, was recently shown to be involved in obesity-induced ß cell dysfunction. However, molecular mechanisms for the association remained elusive. In this study, we first found that both leptin (10 nM) and TNF-α (20 ng/ml) significantly inhibited glucose-stimulated insulin secretion (GSIS) of INS-1E cells. When in combination, the GSIS function of INS-1E cells was significantly increased compared with that of the leptin alone treatment, indicating that TNF-α attenuated the inhibiting effect of leptin on GSIS of INS-1E cells. Similarly, we found that TNF-α has the same inhibitory effect on leptin in regulating insulin synthesis and secretion, and the survival and apoptosis of insulin cells. Further studies showed that TNF-α blocks leptin pathway by reducing the expression of leptin receptor (LepRb, also called OBRb) and inhibiting the activation of STAT3, a key molecule involved in the leptin signaling pathway in INS-1E cells. Besides, the downregulated expression of phosphorylated FOXO1 was found to be involved in the possible mechanism of TNF-α. Overexpression of constitutively active FOXO1 markedly aggravated the LepRb reduction by TNF-α treatment of INS-1E cells, and the endogenous FOXO1 knockdown abolished the effect of TNF-α on INS-1E cells. Furthermore, we have proved that FOXO1 could directly bind to the promoter of LepRb as a negative transcription regulator. Taken together, the results of this study reveal that TNF-α-induced LepRb downregulated in pancreatic ß cells and demonstrate that transcriptional reduction of FOXO1 might be the primary mechanism underlying TNF-α promoting INS-1E leptin resistance and ß cell dysfunction. Conclusions. Our current studies based on INS-1E cells in vitro indicate that the inflammatory factor TNF-α plays an important role in the development of INS-1E leptin resistance and glucose metabolism disorders, probably through FOXO1-induced transcription reduction of LepRb promoter in pancreatic ß cells, and FOXO1 may be a novel target for treating ß cell dysfunction in obesity-induced hyperinsulinemia and T2DM.

A Novel and Rapid Serum Detection Technology for Non-Invasive Screening of Gastric Cancer Based on Raman Spectroscopy Combined With Different Machine Learning Methods.

Gastric cancer (GC) is the fifth most common cancer in the world and a serious threat to human health. Due to its high morbidity and mortality, a simple, rapid and accurate early screening method for GC is urgently needed. In this study, the potential of Raman spectroscopy combined with different machine learning methods was explored to distinguish serum samples from GC patients and healthy controls. Serum Raman spectra were collected from 109 patients with GC (including 35 in stage I, 14 in stage II, 35 in stage III, and 25 in stage IV) and 104 healthy volunteers matched for age, presenting for a routine physical examination. We analyzed the difference in serum metabolism between GC patients and healthy people through a comparative study of the average Raman spectra of the two groups. Four machine learning methods, one-dimensional convolutional neural network, random forest, support vector machine, and K-nearest neighbor were used to explore identifying two sets of Raman spectral data. The classification model was established by using 70% of the data as a training set and 30% as a test set. Using unseen data to test the model, the RF model yielded an accuracy of 92.8%, and the sensitivity and specificity were 94.7% and 90.8%. The performance of the RF model was further confirmed by the receiver operating characteristic (ROC) curve, with an area under the curve (AUC) of 0.9199. This exploratory work shows that serum Raman spectroscopy combined with RF has great potential in the machine-assisted classification of GC, and is expected to provide a non-destructive and convenient technology for the screening of GC patients.

New insight into the aptamer conformation and aptamer/protein interaction by surface-enhanced Raman scattering and multivariate statistical analysis.

We study the interaction between one aptamer and its analyte (the MnSOD protein) by the combination of surface-enhanced Raman scattering and multivariate statistical analysis. We observe the aptamer structure and its evolution during the interaction under different experimental conditions (in air or in buffer). Through the spectral treatment by principal component analysis of a large set of SERS data, we were able to probe the aptamer conformations and orientations relative to the surface assuming that the in-plane nucleoside modes are selectively enhanced. We demonstrate that the aptamer orientation and thus its flexibility rely strongly on the presence of a spacer of 15 thymines and on the experimental conditions with the aptamer lying on the surface in air and standing in the buffer. We reveal for the first time that the interaction with MnSOD induces a large loss of flexibility and freezes the aptamer structure in a single conformation.

Molecule-Specific Terahertz Biosensors Based on an Aptamer Hydrogel-Functionalized Metamaterial for Sensitive Assays in Aqueous Environments.

Metamaterial-inspired terahertz (THz) biosensors are devoted to developing high-sensitivity and label-free biosensing strategies. However, most meaningful molecular signals are obscured by the strong THz absorption of solvent water. Most reported THz biosensors require the tested samples to be tediously dried or replaced with a low-absorption medium, which impairs the original bioactivity and the distribution homogeneity of targets. As described in this proposed strategy, a molecule-specific THz biosensor was fabricated from an aptamer hydrogel-functionalized THz metamaterial. Benefitting from the strong interaction with the localized electric field of the metamaterial, trace thrombin-induced variations in the hydration state of the hydrogel can be sensitively probed, which was investigated experimentally and theoretically. The optimized THz biosensor exhibited remarkable specificity for actual serum sample assays and excellent sensitivity, with a relatively low detection limit of 0.40 pM in the human serum matrix. The proposed strategy could serve as a model system to develop various molecule-specific THz biosensors for aqueous molecule sensing.

Streptavidin-functionalized terahertz metamaterials for attomolar exosomal microRNA assay in pancreatic cancer based on duplex-specific nuclease-triggered rolling circle amplification.

Exosomal microRNA (miRNA) is a promising non-invasive biomarker for liquid biopsies. Herein, we fabricated a terahertz (THz) metamaterial biosensor that comprises an array of gold (Au) discs surrounded by annular grooves for exosomal miRNA assays based on duplex-specific nuclease (DSN)-triggered rolling circle amplification (RCA). In this strategy, the target miRNA is captured by a probe P0 immobilized on magnetic beads (MBs); it then repeatedly releases a primer P1 under the action of DSN, which acts as a highly specific initiator of the subsequent RCA step utilizing biotin-dUTP. After target recycling and nucleic acid amplification, the biotinylated amplification products were captured by the streptavidin (SA)-functionalized THz metamaterials, and further conjugated to SA-modified AuNPs that permit formation of a trimeric complex of SA-biotinylated RCA products-AuNP. The complex population scales with the starting concentration of the target miR-21, resulting in a red shift of the resonance peak of the THz metamaterials. This biosensor can lead to highly specific and sensitive detection with one-base mismatch discrimination and a limit of detection (LOD) down to 84 aM. Significant distinctions are seen in the frequency shifts for exosomal miR-21 quantitation in clinical plasma samples between pancreatic cancer patients and healthy controls. The frequency shifts of the THz metamaterials are consistent versus the reverse transcription-polymerase chain reaction (RT-PCR) results, illustrating the applicability and accuracy of our assay in real clinical samples.

ICBP90 Regulates MIF Expression, Glucocorticoid Sensitivity, and Apoptosis at the MIF Immune Susceptibility Locus.

OBJECTIVE: Macrophage migration inhibitory factor (MIF) is an inflammatory and neurorendocrine mediator that counterregulates glucocorticoid immunosuppression. MIF polymorphisms, which comprise a variant promoter microsatellite (-794 CATT5-8 ), are linked genetically to autoimmune disease severity and to glucocorticoid resistance. While invasive stimuli increase MIF expression, MIF also is up-regulated by glucocorticoids, which serve as a physiologic regulator of inflammatory responses. This study was undertaken to define interactions between the MIF promoter, the glucocorticoid receptor (GR), and the transcription factor inverted CCAAT box binding protein 90 kd (ICBP90) (also referred to as UHRF1), which binds to the promoter in a -794 CATT5-8 length-dependent manner, to regulate MIF transcription. METHODS: Interactions of ICBP90, GR, and activator protein 1 (AP-1) with MIF -794 CATT5-8 promoter constructs were assessed by coimmunoprecipitation, Western blotting, and genetic knockdown. Nuclear colocalization studies were performed using anti-transcription factor antibodies and confocal microscopy of glucocorticoid-treated cells. MIF transcription was studied in CEM-C7 T cells, and the impact of the MIF -794 CATT5-8 microsatellite variation confirmed in peripheral blood T cells and in rheumatoid synovial fibroblasts of defined MIF genotype. Functional interactions were quantified by apoptosis and apoptotic signaling in high- and low-genotypic MIF-expressing human cells. RESULTS: We defined functional interactions between the transcription factors ICBP90, the GR, and AP-1 that up-regulated MIF transcription in a -794 CATT5-8 length-dependent manner. Experimental reduction of ICBP90, GR, or AP-1 decreased MIF expression and increased glucocorticoid sensitivity, leading to enhanced apoptosis in T lymphocytes and in rheumatoid synovial fibroblasts. CONCLUSION: These findings suggest a mechanism for genetic variation of glucocorticoid-regulated MIF transcription, with implications for autoimmune disease severity and glucocorticoid responsiveness.

A novel THz molecule-selective sensing strategy in aqueous environments: THz-ATR spectroscopy integrated with a smart hydrogel.

Terahertz (THz) spectroscopy, with fascinating advantages for biomedical applications, is still in its infancy in terms of the selective detection of aqueous biomolecules because the strong absorption of solvent water always obscures the THz spectroscopic features of biomolecules. Nevertheless, solvent water is not a passive spectator but a useful indicator, as this proposed strategy describes. This strategy utilizes THz attenuated total reflection (THz-ATR) spectroscopy to probe the glucose-induced hydration state changes of smart hydrogels for label-free and selective detection of aqueous glucose. A notable dramatic increase in both the THz absorption coefficient and hydration state (calculated by weighing) of the smart hydrogel was observed with increasing aqueous glucose concentration, which was further verified by a simple two-component model. For aqueous glucose sensing, this method surpasses individual THz-ATR devices and exhibits suitable sensitivity, ideal selectivity and excellent reusability. Moreover, the proposed strategy may provide an alternative option for the selective detection of various aqueous molecules by THz spectroscopy.

An enzyme-powered, three-dimensional lame DNA walker.

Molecular machines constructed by three-dimensional (3-D) DNA walker have emerged as a hot topic in applications such as novel biosensors, cargo delivery platforms and intracellular imaging. Herein, we first propose a lame DNA walker that can randomly and autonomously move on microsphere-based 3-D track. The stochastic lame walker has a long leg mainly responsible for persistent movement and a short leg cutting substrates rapidly. Its motion is propelled by a nicking endonuclease cleavage of hybridized DNA tracks. Kinetic and persistent study show that the lame DNA walker enables reaction equilibrium at 30 min, need a cleat domain of at least 14 nucleotides and can persistently move on 3-D tracks with an average rate of 6.467 × 10-11 M s-1. We also demonstrate that the lame walker can be used to detect target DNA in the detection range of 10 pM-5 nM with high specificity by toehold exchange mechanism. This work will further expand the performance of 3-D DNA walkers and substantially contributes to the improved understanding of DNA walking systems.

A terahertz metamaterial biosensor for sensitive detection of microRNAs based on gold-nanoparticles and strand displacement amplification.

Terahertz (THz) spectroscopy has drawn great interest for the functional and conformational investigations of nucleic acids, but its intrinsic sensitivity hinders potential bio-sensing applications. Here, a novel THz biosensor was developed for detecting microRNA (miRNA) samples based on metamaterials coupled with nanoparticles and strand displacement amplification (SDA). In this method, the SDA reaction amplifies the target miRNA and generates copious yields of secondary DNA molecules (Trigger DNA), which are subsequently conjugated to metallic nanoparticles that form nanoparticle-Trigger DNA complexes. These complexes produce remarkable frequency shifts of metamaterials when linked to a large refractive index metallic nanoparticle like Au. The dependence of the metamaterial resonance on the nanoparticle diameter and metal type was investigated experimentally and theoretically. Under optimal conditions, the THz metamaterial biosensor presents good detection sensitivity with a limit of detection of 14.54 aM and exhibits a linear response for miRNA-21 at a concentration range from 1 fM to 10 pM. By measuring the miRNA-21 in spiked clinical serum samples, the sample recoveries were determined to be in the range between 90.92% and 107.01%. These findings demonstrate that the novel THz biosensor offers the capability for highly sensitive miRNA detection, with noteworthy potential applications in nucleic acid analysis and cancer diagnosis.