Highly Sensitive Poly-N-isopropylacrylamide Microgel-based Electrochemical Biosensor for the Detection of SARS-COV-2 Spike Protein.

Objective: Late 2019 witnessed the outbreak and widespread transmission of coronavirus disease 2019 (COVID-19), a new, highly contagious disease caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Consequently, considerable attention has been paid to the development of new diagnostic tools for the early detection of SARS-CoV-2. Methods: In this study, a new poly-N-isopropylacrylamide microgel-based electrochemical sensor was explored to detect the SARS-CoV-2 spike protein (S protein) in human saliva. The microgel was composed of a copolymer of N-isopropylacrylamide and acrylic acid, and gold nanoparticles were encapsulated within the microgel through facile and economical fabrication. The electrochemical performance of the sensor was evaluated through differential pulse voltammetry. Results: Under optimal experimental conditions, the linear range of the sensor was 10 -13-10 -9 mg/mL, whereas the detection limit was 9.55 fg/mL. Furthermore, the S protein was instilled in artificial saliva as the infected human saliva model, and the sensing platform showed satisfactory detection capability. Conclusion: The sensing platform exhibited excellent specificity and sensitivity in detecting spike protein, indicating its potential application for the time-saving and inexpensive detection of SARS-CoV-2.

Ultrasound super-resolution imaging for the differential diagnosis of thyroid nodules: A pilot study.

Objective: Ultrasound imaging provides a fast and safe examination of thyroid nodules. Recently, the introduction of super-resolution imaging technique shows the capability of breaking the Ultrasound diffraction limit in imaging the micro-vessels. The aim of this study was to evaluate its feasibility and value for the differentiation of thyroid nodules. Methods: In this study, B-mode, contrast-enhanced ultrasound, and color Doppler flow imaging examinations were performed on thyroid nodules in 24 patients. Super-resolution imaging was performed to visualize the microvasculature with finer details. Microvascular flow rate (MFR) and micro-vessel density (MVD) within thyroid nodules were computed. The MFR and MVD were used to differentiate the benign and malignant thyroid nodules with pathological results as a gold standard. Results: Super-resolution imaging (SRI) technique can be successfully applied on human thyroid nodules to visualize the microvasculature with finer details and obtain the useful clinical information MVD and MFR to help differential diagnosis. The results suggested that the mean value of the MFR within benign thyroid nodule was 16.76 ± 6.82 mm/s whereas that within malignant thyroid was 9.86 ± 4.54 mm/s. The mean value of the MVD within benign thyroid was 0.78 while the value for malignant thyroid region was 0.59. MFR and MVD within the benign thyroid nodules were significantly higher than those within the malignant thyroid nodules respectively (p < 0.01). Conclusions: This study demonstrates the feasibility of ultrasound super-resolution imaging to show micro-vessels of human thyroid nodules via a clinical ultrasound platform. The important imaging markers, such as MVD and MFR, can be derived from SRI to provide more useful clinical information. It has the potential to be a new tool for aiding differential diagnosis of thyroid nodules.

Ultrasound Molecular Imaging and Its Applications in Cancer Diagnosis and Therapy.

Ultrasound imaging is regarded as a highly sensitive imaging modality used in routine clinical examinations. Over the last several decades, ultrasound contrast agents have been widely applied in ultrasound molecular cancer imaging to improve the detection, characterization, and quantification of tumors. To date, a few new potential preclinical and clinical applications regarding ultrasound molecular cancer imaging are being investigated. This review presents an overview of the various kinds of ultrasound contrast agents employed in ultrasound molecular imaging and advanced imaging techniques using these contrast agents. Additionally, we discuss the recent enormous development of ultrasound contrast agents in the relevant preclinical and clinical applications, highlight the recent challenges which need to be overcome to accelerate the clinical translation, and discuss the future perspective of ultrasound molecular cancer imaging using various contrast agents. As a highly promising and valuable tumor-specific imaging technique, it is believed that ultrasound molecular imaging will pave an accurate and efficient way for cancer diagnosis.

Breaking Through Bead-Supported Assay: Integration of Optical Tweezers Assisted Fluorescence Imaging and Luminescence Confined Upconversion Nanoparticles Triggered Luminescent Resonance Energy Transfer (LRET).

Herein, a conceptual approach for significantly enhancing a bead-supported assay is proposed. For the fluorescence imaging technology, optical tweezers are introduced to overcome the fluid viscosity interference and immobilize a single tested bead at the laser focus to guarantee a fairly precise imaging condition. For the selection of fluorescent materials and the signal acquisition means, a type of innovative luminescence confined upconversion nanoparticle with a unique sandwich structure is specially designed to act as an efficient energy donor to trigger the luminescent resonance energy transfer (LRET) process. By further combining the double breakthrough with a molecular beacon model, the newly developed detection strategy allows for achieving a pretty high LRET ratio (≈ 88%) to FAM molecules and offering sound assay performance toward miRNA analysis with a detection limit as low as the sub-fM level, and is capable of well identifying single-base mismatching. Besides, this approach not only is able to accurately qualify the low-abundance targets from as few as 30 cancer cells but also can be employed as a valid cancer early warning tool for performing liquid biopsy.

Ultrathin Six-Band Polarization-Insensitive Perfect Metamaterial Absorber Based on a Cross-Cave Patch Resonator for Terahertz Waves.

A simple design of an ultrathin six-band polarization-insensitive terahertz perfect metamaterial absorber (PMMA), composed of a metal cross-cave patch resonator (CCPR) placed over a ground plane, was proposed and investigated numerically. The numerical simulation results demonstrate that the average absorption peaks are up to 95% at six resonance frequencies. Owing to the ultra-narrow band resonance absorption of the structure, the designed PMMA also exhibits a higher Q factor (>65). In addition, the absorption properties can be kept stable for both normal incident transverse magnetic (TM) and transverse electric (TE) waves. The physical mechanism behind the observed high-level absorption is illustrated by the electric and power loss density distributions. The perfect absorption originates mainly from the higher-order multipolar plasmon resonance of the structure, which differs sharply from most previous studies of PMMAs. Furthermore, the resonance absorption properties of the PMMA can be modified and adjusted easily by varying the geometric parameters of the unit cell.

Study of two kinds of Alzheimer's disease tree shrew models / 中国药理学通报

Aim To explore the optimized tree shrews model of Alzheimer's disease through comparison of the pathology changes of brain neurons between the two kinds of tree shrew models.Methods Fifty tree shrews were randomly divided into five groups with 10 in each group:control group,high dose D-galactose combined with ibotenic acid (IBO) group,low dose D-galactose combined with IBO group [intraperitoneal injection D-galactose combined with IBO injection into bilateral basal nucleus of Meynert (BNM)],high dose Aβ25-35 combined with IBO group,and low dose Aβ25-35 combined with IBO group (injection into bilateral BNM).Hematoxylin and eosin (HE) staining was used to observe the morphological changes of brain neurons.The expressions of choline acetyltransterase (ChAT) and synaptophysin(SYP) in the brains were detected by immunohistochemical staining.Western blot was used to detect the expression of amyloid beta 1-42 (Aβ1-42),amyloid precursor protein (APP) and phosphorylated tau protein (p-tau).Results The HE staining showed there were different degrees of morphological changes in the brains of model groups.The changes in the high dose D-galactose and high dose Aβ25-35 combined with IBO group were more obvious than those in low dose D-galactose and Aβ25-35 combined with IBO group.Immunohistochemical staining revealed that the levels of ChAT and SYP in the model groups decreased compared with control group,and the decline in high dose Aβ25-35 combined with IBO group was more marked than that in low dose Aβ25-35 combined with IBO group(P ＜0.01).Western blot revealed that the levels of Aβ1-42,APP,p-tau in the model groups increased compared with control group,and the rise in high dose Aβ25-35 combined with IBO group was more apparent than that in low dose Aβ25-35 combined with IBO group (P ＜ 0.05 or P ＜ 0.01).Conclusion The method of modeling by Aβ25-35 combined with IBO injection into bilateral BNM is more suitable for the establishment of Alzheimer's disease model.