Green Fabrication of Freestanding Piezoceramic Films for Energy Harvesting and Virus Detection

Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.

Sensitive detection of microRNAs using polyadenine-mediated fluorescent spherical nucleic acids and a microfluidic electrokinetic signal amplification chip

The identification of tumor-related microRNAs(miRNAs)exhibits excellent promise for the early diagnosis of cancer and other bioanalytical applications.Therefore,we developed a sensitive and efficient biosensor using polyadenine(polyA)-mediated fluorescent spherical nucleic acid(FSNA)for miRNA analysis based on strand displacement reactions on gold nanoparticle(AuNP)surfaces and electrokinetic signal amplification(ESA)on a microfluidic chip.In this FSNA,polyA-DNA biosensor was anchored on AuNP surfaces via intrinsic affinity between adenine and Au.The upright conformational polyA-DNA recognition block hybridized with 6-carboxyfluorescein-labeled reporter-DNA,resulting in fluorescence quenching of FSNA probes induced by AuNP-based resonance energy transfer.Reporter DNA was replaced in the presence of target miRNA,leading to the recovery of reporter-DNA fluorescence.Subsequently,reporter-DNAs were accumulated and detected in the front of with Nafion membrane in the microchannel by ESA.Our method showed high selectivity and sensitivity with a limit of detection of 1.3 pM.This method could also be used to detect miRNA-21 in human serum and urine samples,with recoveries of 104.0%-113.3% and 104.9%-108.0%,respectively.Furthermore,we constructed a chip with three parallel channels for the simultaneous detection of multiple tumor-related miRNAs(miRNA-21,miRNA-141,and miRNA-375),which increased the detection efficiency.Our universal method can be applied to other DNA/RNA analyses by altering recognition sequences.

A deformability-based biochip for precise label-free stratification of metastatic subtypes using deep learning

Cellular deformability is a promising biomarker for evaluating the physiological state of cells in medical applications.Microfluidics has emerged as a powerful technique for measuring cellular deformability.However,existing microfluidic-based assays for measuring cellular deformability rely heavily on image analysis,which can limit their scalability for high-throughput applications.Here,we develop a parallel constriction-based microfluidic flow cytometry device and an integrated computational framework(ATMQcD).The ATMQcD framework includes automatic training set generation,multiple object tracking,segmentation,and cellular deformability quantification.The system was validated using cancer cell lines of varying metastatic potential,achieving a classification accuracy of 92.4%for invasiveness assessment and stratifying cancer cells before and after hypoxia treatment.The ATMQcD system also demonstrated excellent performance in distinguishing cancer cells from leukocytes(accuracy=89.5%).We developed a mechanical model based on power-law rheology to quantify stiffness,which was fitted with measured data directly.The model evaluated metastatic potentials for multiple cancer types and mixed cell populations,even under realworld clinical conditions.Our study presents a highly robust and transferable computational framework for multiobject tracking and deformation measurement tasks in microfluidics.We believe that this platform has the potential to pave the way for high-throughput analysis in clinical applications,providing a powerful tool for evaluating cellular deformability and assessing the physiological state of cells.

A 6-gene panel as a signature to predict recovery from advanced heart failure using transcriptomic analysis

To the Editor:Heart failure(HF)is a global health problem with a high mortality rate.The various stimuli associated with HF can cause maladaptive remodeling,gradually weakening car-diac functions.Left ventricular assist device(LVAD)can improve advanced HF patients’cardiac functions,termed“reverse remodeling”.1 However,only a small percentage of patients who have received LVAD have experienced reverse remodeling.