Multi-organ proteomic landscape of COVID-19 autopsies.

The molecular pathology of multi-organ injuries in COVID-19 patients remains unclear, preventing effective therapeutics development. Here, we report a proteomic analysis of 144 autopsy samples from seven organs in 19 COVID-19 patients. We quantified 11,394 proteins in these samples, in which 5,336 were perturbed in the COVID-19 patients compared to controls. Our data showed that cathepsin L1, rather than ACE2, was significantly upregulated in the lung from the COVID-19 patients. Systemic hyperinflammation and dysregulation of glucose and fatty acid metabolism were detected in multiple organs. We also observed dysregulation of key factors involved in hypoxia, angiogenesis, blood coagulation, and fibrosis in multiple organs from the COVID-19 patients. Evidence for testicular injuries includes reduced Leydig cells, suppressed cholesterol biosynthesis, and sperm mobility. In summary, this study depicts a multi-organ proteomic landscape of COVID-19 autopsies that furthers our understanding of the biological basis of COVID-19 pathology.

Glutathione safeguards TET-dependent DNA demethylation and is critical for the acquisition of totipotency and pluripotency during preimplantation development.

During early development, both genome-wide epigenetic reprogramming and metabolic remodeling are hallmark changes of normal embryogenesis. However, little is known about their relationship and developmental functions during the preimplantation window, which is essential for the acquisition of totipotency and pluripotency. Herein, we reported that glutathione (GSH), a ubiquitous intracellular protective antioxidant that maintains mitochondrial function and redox homeostasis, plays a critical role in safeguarding postfertilization DNA demethylation and is essential for establishing developmental potential in preimplantation embryos. By profiling mitochondria-related transcriptome that coupled with different pluripotency, we found GSH is a potential marker that is tightly correlated with full pluripotency, and its beneficial effect on prompting developmental potential was functionally conformed using in vitro fertilized mouse and bovine embryos as the model. Mechanistic study based on preimplantation embryos and embryonic stem cells further revealed that GSH prompts the acquisition of totipotency and pluripotency by facilitating ten-eleven-translocation (TET)-dependent DNA demethylation, and ascorbic acid (AsA)-GSH cycle is implicated in the process. In addition, we also reported that GSH serves as an oviductal paracrine factor that supports development potential of preimplantation embryos. Thus, our results not only advance the current knowledge of functional links between epigenetic reprogramming and metabolic remodeling during preimplantation development but also provided a promising approach for improving current in vitro culture system for assisted reproductive technology.

Rich Sulfur Vacancies and Reduced Schottky Barrier Height Synergistically Enable Au/ZnIn2S4 with Enhanced Photocatalytic CO2 Reduction into CO.

Constructing the plasmonic metal/semiconductor heterostructure with a suitable Schottky barrier height (SBH) and the sufficiently reliable active sites is of importance to achieve highly efficient and selective photocatalytic CO2 reduction into hydrocarbon fuels. Herein, we report Au/sulfur vacancy-rich ZnIn2S4 (Au/VSR-ZIS) hierarchical photocatalysts, fabricated via in situ photodepositing Au nanoparticles (NPs) onto the nanosheet self-assembled ZnIn2S4 (ZIS) micrometer flowers (MFs) with rich sulfur vacancies (VS). Density functional theory (DFT) calculations confirm that for the Au/VSR-ZIS system, the Au NPs serve as the reaction sites for H2O oxidation, and the VSR-ZIS MFs serve as those for CO2 reduction. The rich VS in the Au/VSR-ZIS hybrid can reduce its SBH so as to boost more hot electrons in the Au NPs across its Schottky barrier and then inject into the conduction band (CB) of the VSR-ZIS MFs. In addition, VS can also act as the electron sink to trap the photogenerated electrons, retarding the recombination of photogenerated carriers. The two merits effectively enhance the photogenerated electron density in the surface of VSR-ZIS MFs, availing CO2 photoreduction. In addition, the introduction of rich VS in the Au/VSR-ZIS hybrid can offer more active sites, benefiting the CO2 adsorption and accelerating the desorption of CO* from the surface of the photocatalyst. Therefore, under visible light illumination with no sacrificial reagent, the optimum photocatalyst (Au/VSR-ZIS-0.4) presents the enhanced and selective CO2 photoreduction into CO (8.15 µmol g-1h-1 and near 100%), which are superior to those of most of ZIS-based and plasmon-based photocatalysts. The photocatalytic activity is about 40.0-fold as high as that of the Vs-poor-ZIS (VSP-ZIS) MFs. This work contributes a viable strategy for designing highly efficient plasmonic photocatalysts by using the synergism of the anion vacancies and the optimized SBH induced by them.

Integrated analysis of transcriptome and metabolome reveals the regulatory mechanism of largemouth bass (Micropterus salmoides) in response to Nocardia seriolae infection.

Nocardia seriolae is a severe bacterial pathogen that has seriously affected the development of aquaculture industry. Largemouth bass (Micropterus salmoides) is a commercially significant freshwater fish that suffers a variety of environmental threats, including bacterial pathogens. However, the immune responses and metabolic alterations of largemouth bass to N. seriolae infection remain largely unclear. We discovered that N. seriolae caused pathological alterations in largemouth bass and shifted the transcript of immune-related and apoptotic genes in head kidney after infection. To answer the aforementioned question, a combined transcriptome and metabolome analysis was employed to explore the alterations in genes, metabolites, and metabolic pathways in largemouth bass following bacterial infection. A total of 3579 genes and 1929 metabolites are significant differentially changed in the head kidney post infection. In response to N. seriolae infection, host modifies the PI3K-Akt signaling pathway, TCA cycle, glycolysis, and amino acid metabolism. The integrated analysis of transcriptome and metabolome suggested that with the arginine metabolism pathway as the core, multiple biomarkers (arg gene, arginine) are involved in the antibacterial and immune functions of largemouth bass. Thus, we hypothesized that arginine plays a crucial role in the immune responses of largemouth bass against N. seriolae infection, and increasing arginine levels suitably is beneficial for the host against bacterial infection. Our results shed light on the regulatory mechanism of largemouth bass resistance to N. seriolae infection and contributed to the development of more effective N. seriolae resistance strategies.

Discovery of a prominent dual-target DDR1/EGFR inhibitor aimed DDR1/EGFR-positive NSCLC.

This study aimed to develop the first dual-target small molecule inhibitor concurrently targeting Discoidin domain receptor 1 (DDR1) and Epidermal growth factor receptor (EGFR), which play a crucial interdependent roles in non-small cell lung cancer (NSCLC), demonstrating a synergistic inhibitory effect. A series of innovative dual-target inhibitors for DDR1 and EGFR were discovered. These compounds were designed and synthesized using structural optimization strategies based on the lead compound BZF02, employing 4,6-pyrimidine diamine as the core scaffold, followed by an investigation of their biological activities. Among these compounds, D06 was selected and showed micromolar enzymatic potencies against DDR1 and EGFR. Subsequently, compound D06 was observed to inhibit NSCLC cell proliferation and invasion. Demonstrating acceptable pharmacokinetic performance, compound D06 exhibited its anti-tumor activity in NSCLC PC-9/GR xenograft models without apparent toxicity or significant weight loss. These collective results showcase the successful synthesis of a potent dual-targeted inhibitor, suggesting the potential therapeutic efficacy of co-targeting DDR1 and EGFR for DDR1/EGFR-positive NSCLC.

Establishment of diagnostic model and identification of diagnostic markers between liver cancer and cirrhosis based on multi-chip and machine learning.

OBJECTIVE: Most cases of hepatocellular carcinoma (HCC) arise as a consequence of cirrhosis. In this study, our objective is to construct a comprehensive diagnostic model that investigates the diagnostic markers distinguishing between cirrhosis and HCC. METHODS: Based on multiple GEO datasets containing cirrhosis and HCC samples, we used lasso regression, random forest (RF)-recursive feature elimination (RFE) and receiver operator characteristic analysis to screen for characteristic genes. Subsequently, we integrated these genes into a multivariable logistic regression model and validated the linear prediction scores in both training and validation cohorts. The ssGSEA algorithm was used to estimate the fraction of infiltrating immune cells in the samples. Finally, molecular typing for patients with cirrhosis was performed using the CCP algorithm. RESULTS: The study identified 137 differentially expressed genes (DEGs) and selected five significant genes (CXCL14, CAP2, FCN2, CCBE1 and UBE2C) to construct a diagnostic model. In both the training and validation cohorts, the model exhibited an area under the curve (AUC) greater than 0.9 and a kappa value of approximately 0.9. Additionally, the calibration curve demonstrated excellent concordance between observed and predicted incidence rates. Comparatively, HCC displayed overall downregulation of infiltrating immune cells compared to cirrhosis. Notably, CCBE1 showed strong correlations with the tumour immune microenvironment as well as genes associated with cell death and cellular ageing processes. Furthermore, cirrhosis subtypes with high linear predictive scores were enriched in multiple cancer-related pathways. CONCLUSION: In conclusion, we successfully identified diagnostic markers distinguishing between cirrhosis and hepatocellular carcinoma and developed a novel diagnostic model for discriminating the two conditions. CCBE1 might exert a pivotal role in regulating the tumour microenvironment, cell death and senescence.

Effect of acupuncture on regulating IL-17, TNF-ɑ and AQPs in Sjögren's syndrome.

AIM: The aim of the study was to observe the effect of acupuncture on regulating interleukin (IL)-17, tumor necrosis factor (TNF)-ɑ, and aquaporins (AQPs) in Sjögren's syndrome (SS) on patients and on non-obese diabetic (NOD) models. METHODS: Levels of anti-AQP 1, 5, 8, and 9 antibodies, IL-17, and TNF-ɑ in the serum of SS patients were compared prior and following 20 acupuncture treatment visits during 8 weeks. While in murine model, five groups were divided to receive interventions for 4 weeks, including control, model, acupuncture, isoflurane, and hydroxychloroquine. The submaxillofacial gland index, histology, immunohistochemistry of AQP1, 5, salivary flow, together with IL-17, and TNF-ɑ expression in peripheral blood were compared among the groups. RESULTS: Acupuncture reduced IL-17, TNF-ɑ, and immunoglobin A levels, and numeric analog scale of dryness in 14 patients with SS (p < 0.05). The salivary flow was increased, and the water intake decreased in NOD mice receiving acupuncture treatments. IL-17 and TNF-ɑ levels in peripheral serum were down-regulated (p < 0.05) and AQP1, 5 expression in the submandibular glands up-regulated in mice. CONCLUSION: The effect on relieving xerostomia with acupuncture may be achieved by up-regulating the expression of AQP1. AQP5, down-regulating levels of IL-17 and TNF-ɑ, and a decrease in inflammation of glands.

Deep Circumflex Iliac Artery-vascularized Iliac Bone Graft for Femoral Head Osteonecrosis: Computed Tomography Anatomical Study.

BACKGROUND: Deep circumflex iliac artery (DCIA)-vascularized iliac graft transposition is a method for treating femoral head osteonecrosis but with inconsistent efficacy. We aim to improve the method of this surgery by recommending the optimal location of the iliac pedicle to satisfy the vascular length for transposition and the blood supply of the vascularized iliac graft. METHODS: The DCIA and its surrounding tissues were assessed on computed tomography angiography images for 100 sides (left and right) of 50 patients. The length of the vascular pedicle required for transposition and the length of the pedicle at different iliac spine positions were compared. The diameter and cross-sectional area of the DCIA and the distance between the DCIA and iliac spine were measured at different points to assess blood supply. We also compared differences in sex and left-right position. RESULTS: The diameter and cross-sectional area of the DCIA gradually decreased after crossing the anterior superior iliac spine (ASIS), and it approached the iliac bone. However, when the DCIA was 4 cm behind the ASIS (54 sides, 54%), it coursed posteriorly and superiorly away from the iliac spine. The vascular length of the pedicle was insufficient to transpose the vascularized iliac graft to the desired position when it was within 1 cm of the ASIS. The vascular length requirement was satisfied, and the blood supply was sufficient when the pedicle was positioned at 2 or 3 cm. CONCLUSION: To obtain a satisfactory pedicle length and sufficient blood supply, the DCIA pedicle of the vascularized iliac graft should be placed 2 to 3 cm behind the ASIS. The dissection of DCIA has slight differences in sex and left-right position due to anatomical differences.

Integration of protein context improves protein-based COVID-19 patient stratification.

BACKGROUND: Classification of disease severity is crucial for the management of COVID-19. Several studies have shown that individual proteins can be used to classify the severity of COVID-19. Here, we aimed to investigate whether integrating four types of protein context data, namely, protein complexes, stoichiometric ratios, pathways and network degrees will improve the severity classification of COVID-19. METHODS: We performed machine learning based on three previously published datasets. The first was a SWATH (sequential window acquisition of all theoretical fragment ion spectra) MS (mass spectrometry) based proteomic dataset. The second was a TMTpro 16plex labeled shotgun proteomics dataset. The third was a SWATH dataset of an independent patient cohort. RESULTS: Besides twelve proteins, machine learning also prioritized two complexes, one stoichiometric ratio, five pathways, and five network degrees, resulting a 25-feature panel. As a result, a model based on the 25 features led to effective classification of severe cases with an AUC of 0.965, outperforming the models with proteins only. Complement component C9, transthyretin (TTR) and TTR-RBP (transthyretin-retinol binding protein) complex, the stoichiometric ratio of SAA2 (serum amyloid A proteins 2)/YLPM1 (YLP Motif Containing 1), and the network degree of SIRT7 (Sirtuin 7) and A2M (alpha-2-macroglobulin) were highlighted as potential markers by this classifier. This classifier was further validated with a TMT-based proteomic data set from the same cohort (test dataset 1) and an independent SWATH-based proteomic data set from Germany (test dataset 2), reaching an AUC of 0.900 and 0.908, respectively. Machine learning models integrating protein context information achieved higher AUCs than models with only one feature type. CONCLUSION: Our results show that the integration of protein context including protein complexes, stoichiometric ratios, pathways, network degrees, and proteins improves phenotype prediction.

Hierarchical S-Scheme Heterostructure of CdIn2S4@UiO-66-NH2 toward Synchronously Boosting Photocatalytic Removal of Cr(VI) and Tetracycline.

Developing highly efficient photocatalysts toward synchronously removing heavy metals and organic pollutants is still a serious challenge. Herein, we depict hierarchical S-scheme heterostructured photocatalysts prepared via in situ anchoring UiO-66-NH2 nanoparticles onto the CdIn2S4 porous microsphere structures assembled with numerous nanosheets. In the mixed system of Cr(VI) and tetracycline (TC), the optimal photocatalyst (CIS@U66N-30) shows remarkable photocatalytic activities toward the synchronous removal of Cr(VI) (97.26%) and TC (close to 100% of) under visible-light irradiation for 60 min, being the best removal rates among those of the reported photocatalysts, and sustains the outstanding stability and reusability. Its reaction rate constants of Cr(VI) reduction and TC degradation are about 2.06 and 1.58 folds that in the single Cr(VI) and TC systems, respectively. The enhanced photocatalytic activities of CIS@U66N-30 mainly result from the following synergism: (1) its hierarchical structure offers abundant active sites, and the S-scheme migration mechanism of charge carriers in the heterostructure accelerates the separation and migration of the useful photoinduced electrons and holes with the high redox capability; (2) Cr(VI) and TC can serve as the electron scavenger for TC oxidation degradation and the hole and •OH scavenger for Cr(VI) reduction, respectively, further enhancing the separation and utilization efficiency of photoinduced electrons and holes. Besides, the possible TC degradation pathway and plausible S-scheme photocatalytic mechanism over CIS@U66N-30 for the concurrent elimination of Cr(VI) and TC are proposed.

Recent Progress in Improving the Performance of Infrared Photodetectors via Optical Field Manipulations.

Benefiting from the inherent capacity for detecting longer wavelengths inaccessible to human eyes, infrared photodetectors have found numerous applications in both military and daily life, such as individual combat weapons, automatic driving sensors and night-vision devices. However, the imperfect material growth and incomplete device manufacturing impose an inevitable restriction on the further improvement of infrared photodetectors. The advent of artificial microstructures, especially metasurfaces, featuring with strong light field enhancement and multifunctional properties in manipulating the light-matter interactions on subwavelength scale, have promised great potential in overcoming the bottlenecks faced by conventional infrared detectors. Additionally, metasurfaces exhibit versatile and flexible integration with existing detection semiconductors. In this paper, we start with a review of conventionally bulky and recently emerging two-dimensional material-based infrared photodetectors, i.e., InGaAs, HgCdTe, graphene, transition metal dichalcogenides and black phosphorus devices. As to the challenges the detectors are facing, we further discuss the recent progress on the metasurfaces integrated on the photodetectors and demonstrate their role in improving device performance. All information provided in this paper aims to open a new way to boost high-performance infrared photodetectors.

Skin effect photon-trapping enhancement in infrared photodiodes.

With the development of infrared optoelectronic technology, high responsivity, ultra-low dark current, and high response speed have become important factors of the next generation of infrared photodiodes. However, the minimum thickness of the absorber layer is limited to approximately one or several wavelength lengths to acquire high quantum efficiency, which results in a long transit time of photogenerated carriers. In this work, we propose a photon-trapping structure that uses the skin effect of metals to generate horizontal local modes to enhance the absorption of infrared photodiodes. The photon-trapping structure consists of an artificial grating structure covered by a metallic film. Importantly, we develop a simplified theoretical model to describe the local mode, which is then being used to design the realistic photon-trapping structure presented in this work. This design method is universal and we discuss the optical properties of the photon-trapping structure in InAs, InSb, InAs/GaSb type-II superlattices, InAs/InAsSb type-II superlattices, and HgCdTe infrared photodiodes. Both absorption of optical properties and responsivity of optoelectrical properties are numerically investigated in a systematic way. The optical simulations indicate that the absorption of the HgCdTe infrared photodiodes exceeds 80% at 8.5 ∼ 11 µm with a maximum value of 95% at 9.73 µm. The optoelectrical simulations show that the responsivity at 7 ∼ 10 µm is significantly enhanced compared to that of the plain HgCdTe infrared photodiodes without the photon-trapping structure. We further investigate the optical crosstalk in the HgCdTe pixel array employing the photon-trapping structure. The optical crosstalk significantly reduces as the pixel spacing increases. Our work provides a design method for developing small pixel, large scale, and low dark current focal plane array infrared photodiodes.

Gate-Tunable Semiconductor Heterojunctions from 2D/3D van der Waals Interfaces.

van der Waals (vdW) semiconductors are attractive for highly scaled devices and heterogeneous integration as they can be isolated into self-passivated, two-dimensional (2D) layers that enable superior electrostatic control. These attributes have led to numerous demonstrations of field-effect devices ranging from transistors to triodes. By exploiting the controlled, substitutional doping schemes in covalently bonded, three-dimensional (3D) semiconductors and the passivated surfaces of 2D semiconductors, one can construct devices that can exceed performance metrics of "all-2D" vdW heterojunctions. Here, we demonstrate 2D/3D semiconductor heterojunctions using MoS2 as the prototypical 2D semiconductor laid upon Si and GaN as the 3D semiconductor layers. By tuning the Fermi levels in MoS2, we demonstrate devices that concurrently exhibit over 7 orders of magnitude modulation in rectification ratios and conductance. Our results further suggest that the interface quality does not necessarily affect Fermi level tuning at the junction, opening up possibilities for novel 2D/3D heterojunction device architectures.

Design of a bandgap-engineered barrier-blocking HOT HgCdTe long-wavelength infrared avalanche photodiode.

The performance of high-operating-temperature (HOT) longwavelength infrared (LWIR) HgCdTe avalanche photodiodes (APDs) is significantly limited by the increasing dark current related to temperature. In this paper, a novel barrier-blocking LWIR pBp-APD structure is proposed and studied, and the results show that the dark current of pBp-APD is significantly restricted compared with conventional APD without sacrificing the gain at high temperature. Furthermore, the reduction of avalanche dark current is found to be the key points of the significant suppression of dark current. The physical essence of this reduction is revealed to be the depletion of carriers in the absorption region, and the feasibility of the improved structure is further confirmed by the analysis of its energy band and electric field distribution. In addition, the reduction of gain-normalized dark current (GNDC) does not need to sacrifice the gain. The proposed LWIR pBp-APD paves the way for development of high operation temperature infrared APDs.

A versatile fluorometric in situ hybridization method for the quantitation of hairpin conformations in DNA self-assembled monolayers.

As the performance of hairpin DNA (hpDNA)-based biosensors is highly dependent on the yield of stem-loop (hairpin) conformations, we report herein a versatile fluorometric in situ hybridization protocol for examining hpDNA self-assembled monolayers (SAMs) on popularly used biochip substrates. Specifically, the ratio of fluorescence (FL) intensities of hpDNA SAMs (in an array format) before and after hybridization was adopted as the key parameter for performing such a determination. Upon confirming the existence of mixed and tunable DNA conformations in binary deposition solutions and efficient hybridization of the hairpin strands with the target DNA via gel electrophoresis assays, we tested the fluorometric protocol for determining the coverages of hpDNA in hpDNA/ssDNA SAMs prepared on gold; its accuracy was validated by Exonuclease I (Exo I)-assisted electrochemical quantitation. To further confirm its versatility, this FL protocol was adopted for quantifying hairpin conformations formed on glass and polycarbonate (PC) substrates. The molar ratios of surface-tethered hairpin conformations on the three different substrates were all found to be proportional to but less than those in the binary deposition solutions, and were dependent on the substrate morphology. The findings reported herein are beneficial for the construction of highly efficient DNA hairpin-based sensing surfaces, which essentially facilitates the creation of hpDNA-based biosensors with optimal detection performance.

[The Therapeutic Effect and Mechanism of Static Progressive Stretching in Different Durations on Traumatic Knee Contracture in Rats].

OBJECTIVE: To investigate the effect and mechanism of static progressive stretching (SPS) in different durations on traumatic knee contracture in rats. METHODS: Seventy male Wistar rats were randomly divided into three groups, including surgical modeling group ( n=50), control group (CON, no surgery, no treatment, n=10) and trauma without immobilization group (TRA, no treatment, n=10). The knee contracture model was established, and 50 surgical modeling rats were randomly divided into five groups including static progressive stretching treatment for 20 minutes group (S20 min, n=10), treatment for 30 minutes group (S30 min, n=10), treatment for 40 minutes group (S40 min, n=10), untreatment group (UNT, no SPS, n=10) and modeling group (MOD, n=10, euthanized after immobilization for histological staining and Western blot). Individuals in the S20 min, S30 min, and S40 min groups were anesthetized and submitted to SPS. One treatment session took place every other day. A total of 8 sessions were given till the final treatment session on the day 16. On the day 0, 8, and 16 of intervention, the range of joint motion (ROM) and gait analysis were measured and compared. After the ROM measurements and gait analysis, the rats were euthanized on the day 16 and the samples were stained with HE and Masson methods. The changes of pathological organization were observed. Western blot was used to detect the expressions of transforming growth factor-ß1 (TGF-ß1) and interleukin-6 (IL-6). RESULTS: ① ROM：the ROM of S30 min group recovered similar to that of the S20 min and S40 min groups after 8 days of treatment ( P>0.05), and was the best among all the surgical modeling groups after 16 d of treatment ( P<0.05). The ROM of S20 min, S30 min and S40 min groups significantly improved on the day 8 and day 16 comparing with that on day 0 ( P<0.01). ② Gait analysis: the stands in the S30min group improved best on the day 8 and day 16 ( P<0.05) , and better than that on day 0 ( P<0.05). The stride length of the S30 min group progressed similar to that of the S40 min group on the day 8 ( P>0.05), and there was no difference among three groups on the day 16 ( P>0.05). The stride length of the S30 min group appeared to recover more quickly on the day 8 ( P<0.05), and those of S20 min and UNT groups recovered significantly on the day 16 ( P<0.05). In addition, the swings in the S30 min group improved best ( P<0.05), and it appeared to recover better on the day 16 ( P<0.05). There was no statistical difference in terms of the swing speed among the four surgical modeling groups on the day 8 ( P>0.05). The swing speed of the S30min group increased most than those of the other three groups ( P<0.05), and it was much better on the day 8 and day 16 comparing with that on the day 0 ( P<0.05 ). ③ HE and Masson staining: the fibrosis and inflammation of the S30min group were significantly suppressed comparing to the other groups on the day 16. ④ Western blot: The protein expression levels of TGF-ß1 and IL-6 were significantly lower than those in the other intervention groups including the S20 min, S40 min and UNT groups on the day 16 ( P<0.05). CONCLUSION: Static progressive stretching treatment for 30 min could significantly improve the traumatic knee contracture in rats. The mechanism may be that the SPS decreased the expressions of TGF-ß1 and IL-6, reduced the adhesion and inflammation of joint capsule. Therefore it relieved the pain and increased the joint mobility by reconstructing the structure of the capsule and suppressing the fibrotic changes.

Systematic truncating of aptamers to create high-performance graphene oxide (GO)-based aptasensors for the multiplex detection of mycotoxins.

Graphene oxide (GO)-based aptasensors are currently one of the most popular sensing platforms for the simple and rapid detection of various targets. Unfortunately, the GO-based aptasensors with long aptamer strands typically show unsatisfactory performance resulting from insignificant structural transformations upon target binding. We report herein the utilization of an aptamer-truncating strategy to combat such a challenge. Taking a pre-selected anti-aflatoxin B1 (AFB1) aptamer (P-AFB1-50) as a trial system, we sequentially remove the extraneous nucleotides within the aptamer by means of circular dichroism (CD) spectroscopy and binding affinity analysis. Particularly, the ratio of the quenching constants between the GO sheets and the truncated aptamers (labelled with fluorophores) in the absence and presence of the target was determined for each of the truncated aptamers to evaluate the optimal sequence. As a result, the truncated aptamer comprising 40 nucleotides was confirmed to show the highest FL output and the best detection limit upon conjugation with GO sheets. More importantly, we demonstrated that this truncating strategy is versatile, i.e., it can be easily extended to other aptamer systems (anti-ochratoxin A (OTA) aptamer, P-OTA-61, as an example) for extraneous nucleotide identification. Impressively, the two optimal truncated aptamers can work together on GO sheets to achieve a simultaneous detection of two different mycotoxins (i.e., AFB1 and OTA) in one single test. Essentially, this research opens a new avenue for the design and testing of aptamer-/GO-based-sensing platforms for rapid, low-cost and multiplex quantification of analytical targets of interest.

Exonuclease I-Hydrolysis Assisted Electrochemical Quantitation of Surface-Immobilized DNA Hairpins and Improved HIV-1 Gene Detection.

The complete formation of stem-loop (i.e., hairpin) configuration on chip surface is of particular importance for the application of hairpin DNA (hpDNA) in building biosensors for various analytes with optimized performance. We report herein a convenient electrochemical protocol for evaluating the yield of hairpin DNA conformations upon self-assembly on electrode surface. As of the different hydrolysis capability of Exonuclease I (Exo I) toward single-stranded DNA (ssDNA) and hpDNA, we can selectively remove ssDNA from electrode but retain hpDNA strands; based on the changes in the cyclic voltammetric (CV) responses using [Ru(NH3)6]3+ as redox indicators, we can then determine the fraction of hairpin configurations in mixed DNA self-assembled monolayers (SAMs). It was discovered that the molar fraction of hairpin configuration formed on the surface is considerably lower than that in the binary deposition solution (containing both ssDNA and hpDNA). The accuracy of the Exo I-assisted electrochemical quantitative protocol has been validated by standard DNA hybridization experiments; the relationship between the overall DNA packing density and the yield of hairpin configurations was also evaluated. More importantly, taking HIV-1 gene detection as a trial system, the hpDNA-based biosensor shows significantly improved detection limit and broadened response range upon the background reduction by Exo I-catalyzed hydrolysis.

Fourier transform imaging spectropolarimeter using ferroelectric liquid crystals and Wollaston interferometer.

A time-division Fourier transform imaging spectropolarimeter (FTISP) for acquiring spatial, spectral, and polarized information is presented. The FTISP employs two ferroelectric liquid crystals (FLCs) and a Wollaston interferometer. The fast axes of the FLCs are controlled to switch quickly without mechanical movement, enabling the polarization state analyzer (PSA) to modulate the full set of Stokes parameters rapidly. The interferometer combines a Wollaston prism with a retroreflector, enabling high interference modulation and facilitating optical alignment. The optimal design for the FLC-PSA and Wollaston interferometer, and the Fourier transform recovery for the polarized interferogram, are presented in detail. To verify the proposed FTISP, laboratory and outdoor experiments were conducted, and the experimental results demonstrate that the proposed FTISP offers much promise for spectropolarimetric measurement with the advantages of fast speed, high spectral resolution, and high signal-to-noise ratio.

Experimental demonstration of high spectral efficient 4 × 4 MIMO SCMA-OFDM/OQAM radio over multi-core fiber system.

In this paper, 4 × 4 multiple-input multiple-output (MIMO) radio over 7-core fiber system based on sparse code multiple access (SCMA) and OFDM/OQAM techniques is proposed. No cyclic prefix (CP) is required by properly designing the prototype filters in OFDM/OQAM modulator, and non-orthogonally overlaid codewords by using SCMA is help to serve more users simultaneously under the condition of using equal number of time and frequency resources compared with OFDMA, resulting in the increase of spectral efficiency (SE) and system capacity. In our experiment, 11.04 Gb/s 4 × 4 MIMO SCMA-OFDM/OQAM signal is successfully transmitted over 20 km 7-core fiber and 0.4 m air distance in both uplink and downlink. As a comparison, 6.681 Gb/s traditional MIMO-OFDM signal with the same occupied bandwidth has been evaluated for both uplink and downlink transmission. The experimental results show that SE could be increased by 65.2% with no bit error rate (BER) performance degradation compared with the traditional MIMO-OFDM technique.