Modular Combination of Proteolysis-Responsive Transcription and Spherical Nucleic Acids for Smartphone-Based Colorimetric Detection of Protease Biomarkers.

Sensitive and facile detection of biomarkers is essential for early diagnosis and treatment of diseases. To this end, we here proposed a colorimetric protease assay by the modular combination of proteolysis-responsive transcription and spherical nucleic acids (SNAs). In this assay, target protease-mediated proteolysis triggers the synthesis of RNAs by in vitro transcription, which subsequently results in the aggregation of SNAs with remarkable redshifts in the wavelength of surface plasmon resonance-related absorption. As a proof of concept, this assay achieved the sensitive and specific detection of matrix metalloprotease-2 (MMP-2) with a limit of detection of 3.3 pM. Moreover, the applicability of this colorimetric assay can be expanded to other protease biomarkers (e.g., thrombin and hepatitis C virus NS3/4A) by tuning the target-responsive RNA polymerase module. Furthermore, by the immobilization of SNAs on a glass fiber membrane, a test strip that enables the portable detection of target protease with a smartphone was developed. With the use of a mobile application to capture and process the colorimetric signals, this portable detection system allowed for sensitive evaluation of MMP-2 levels in biological and clinical specimens, highlighting its potential in point-of-care diagnosis of diseases.

Dual-Product Synergistically Enhanced Colorimetric Assay for Sensitive Detection of Lipid Transferase Activity.

Lipid transferase-catalyzed protein lipidation plays critical roles in many physiological processes and it has been an increasingly attractive therapeutic target from cancer to neurodegeneration, while sensitive detection of lipid transferase activity in biological samples remains challenging. Here, we presented an AuNP-based colorimetric method with dual-product synergistically enhanced sensitivity for convenient detection of lipid transferase activity. Homo sapiens N-myristoyltransferase 1 (HsNMT1), a key lipid transferase, was selected as the model. Accordingly, positively charged substrate peptides (Pep) of HsNMT1 can induce the aggregation of AuNPs through disrupting their electrostatic repulsion, while the HsNMT1-catalyzed lipid modification generates aggregated lipidated peptides (C14-Pep) and negatively charged HS-CoA, which will eliminate the disruption and stabilize the AuNPs by the formation of Au-S bonds, respectively. Consequently, charge reversal of the biomolecules and the formation of Au-S bonds synergistically contribute to the stability of AuNPs in the presence of HsNMT1. Therefore, the HsNMT1 activity can be visually detected by the naked eye through the color change of the AuNPs originated from the change in their distance-dependent surface plasmon resonance absorptions. Here, the A520/A610 ratio can sensitively reflect the activity of HsNMT1 in the linear range of 2-75 nM with a low detection limit of 0.56 nM. Moreover, the method was successfully applied for probing the HsNMT1 activities in different cell lysates and inhibitor screening. Furthermore, given the replaceability of the substrate peptide, the proposed assay is promising for universal application to other lipid transferases and exhibits great potential in lipid transferase-targeted drug development.

Very low frequency three-dimensional beamforming for a miniaturized aperture acoustic vector sensor array.

In this Letter, a three-dimensional beamforming method is proposed for a miniaturized aperture acoustic vector sensor (AVS) array. This method extracts the multipole modes using the AVS array, and then synthesizes the desired beam pattern according to the relation between multipole modes and spherical harmonics. Compared to the spherical harmonics decomposition of the sound field method, the proposed method achieves comparable array gain with higher white noise gain when the distance of adjacent elements d and the wavelength λ satisfy 0.01≤d/λ≤0.2. Experimental results also demonstrate the effectiveness of the proposed three-dimensional beamforming method at very low frequency.

Does preoperative morphology of multifidus influence the surgical outcomes of stand-alone lateral lumbar interbody fusion for lumbar spondylolisthesis?

OBJECTIVES: To investigate whether the preoperative morphology of multifidus influences the surgical outcomes of stand-alone lateral lumbar interbody fusion (LLIF) for lumbar spondylolisthesis. PATIENTS AND METHODS: Fifty-eight patients with lumbar spondylolisthesis who underwent single-level, stand-alone LLIF at the L4-5 level were included and followed up for at least 12 months. Preoperative axial cross-sectional area (CSA) and fat infiltration rate (FIR) of multifidus on MRI scans were measured using the ImageJ software. The CSA ratio and FIR were calculated and classified into three grades. Preoperative and final visual analogue scale (VAS) scores for back pain and leg pain, Oswestry Disability Index (ODI) scores were recorded. Cage subsidence and fusion were also evaluated at the final follow-up. Correlations between VAS scores, ODI scores, obvious cage subsidence and fusion rate with the CSA ratio and FIR were analyzed. RESULTS: There were significant correlations between preoperative and final VAS scores for back pain and ODI scores with the CSA ratio and FIR. There was an overall trend towards improvements in back pain and lumbar function in patients with superior morphology of multifidus. In addition, obvious cage subsidence was found to be associated with lower preoperative CSA ratios and higher FIR, whereas fusion rate was only correlated with FIR. CONCLUSIONS: The preoperative morphology of multifidus influenced the surgical outcomes of stand-alone LLIF for lumbar spondylolisthesis. Patients with superior morphology of multifidus showed better outcomes following stand-alone LLIF.