Wearable spectral sensors are integrated smart devices consisting of flexible substrates,sensing and detection units,and analysis units.These sensors can track chemicals in human fluids including sweat,transdermal gases,wound secretions,subcutaneous mesenchymal fluids,tears,exhaled gases,and saliva quickly and non-invasively.Their application is crucial in drug analysis,disease diagnosis,and health monitoring.This paper summarized the literature studies of wearable colorimetric,fluorescence and surface-enhanced Raman scattering sensors since 2016,and reviewed the advancements in wearable spectroscopic sensors,focusing on their composition and applications in epidermal,ocular,and oral forms.Additionally,the future challenges and opportunities of wearable spectroscopic sensors were discussed,providing a reference for the design and development of wearable spectroscopic sensors.

The usage of pesticides can enhance the production of crops,but their overuses may be hazardous to both people health and the environment.Thus,it is of great significance to develop effective methods to detect pesticides.Metal nanoclusters(MNCs)have become increasingly popular in analytical sensing areas because of their miniscule size,high stability,ease of manufacturing and good biocompatibility.They have exhibited great potential in the field of pesticides detection.In this paper,the detection methods of pesticides by using MNCs and their development in detection of organophosphorus pesticides,organic nitrogen pesticides,organochlorine pesticides and other types of pesticides were reviewed.Finally,the development prospects were discussed.

Rapid and accurate detection methods for food-borne pathogens are essential to ensure food safety and human health.One promising innovation in this area is the clustered regularly interspaced short palindromic repeats/CRISPR-associated systems(CRISPR/Cas)biosensor,which utilizes Cas protein and CRISPR RNA(crRNA)ribonucleo protein to specifically recognize target genes,and converts target signals into detectable physical and chemical signals.The CRISPR/Cas biosensor shows many advantages,such as high specificity,programmability,and ease of use,making it promising to pathogen detection.This paper introduced the principles and characteristics of CRISPR/Cas systems,along with the strategies for signal recognition,amplification,and output based on different CRISPR/Cas biosensors,and their respective applications in food-borne pathogen detection.Furthermore,the construction principles and challenges of multiple biosensors based on CRISPR/Cas were explored,as well as their potential for simultaneous detection of multiple pathogens.Finally,the challenges and future development trends of CRISPR/Cas-based biosensors in rapid pathogen detection were discussed,aiming to provide valuable reference and inspiration for biosensor designers and food safety practitioners.

RNA fluorescence aptamers are RNA sequences that can specifically bind to non-toxic,cell permeable,and self-fluorescent target molecules and activate their luminescent properties.These aptamers provide powerful tools for biosensing and imaging researches due to their simple structure,easy synthesis,and easy transfection.This article summarized the characteristics and development history of various RNA fluorescent aptamers,including Malachite Green,Spinach,Broccoli,Mango,Corn,and Pepper family,as well as their corresponding fluorescent groups.The applications of RNA fluorescent aptamers were also reviewed from two aspects:extracellular detection and cell imaging.This review might provide guidance for labeling,detection and interactions of molecules from proof of concept and clinical assessment to practical clinical and biomedical applications.

Fluorescent carbon dots(CDs)were synthesized via a solvothermal method with citric acid and urea as raw materials,and ethylene glycol as reaction solvent.The micromorphology,crystal structure,elemental composition,surface functional group,and optical property of as-synthesized CDs were characterized.The excitation-dependent fluorescence property of CDs was investigated,and the effects of synthesis conditions including reaction temperature,reaction time and raw materials on excitation and emission wavelengths of the CDs were also discussed.Then,a series of CDs-based fluorescent composites were prepared by combining CDs with starch,nano-silica,montmorillonite,kaoline,kieselguhr and magnesium oxide,respectively.Finally,the CDs-starch composites were used for latent fingerprint development on smooth substrates,and the qualitative as well as quantitative evaluation of the contrast,sensitivity and selectivity in fingerprint development were also made.Enhanced development of latent fingerprints was thus achieved by the aid of the excitation-dependent fluorescence property of CDs-starch composite combined with the optical filtering technique,which could decrease the background noise interference to a great extent.Experimental results showed that,the contrast between fingerprint(developing signal)and substrate(background noise)was obvious,exhibiting a strong contrast;the minutiae of papillary ridges were clear,indicating a high sensitivity;the adsorption between CDs-starch composites and fingerprint residues was specific,showing a good selectivity.

Inertial microfluidics,as a microfluidic technology with the ability to precisely manipulate particles and cells with high throughput,has attracted widespread attention.However,challenges remain in achieving particle focusing with insensitivity to flow rates in large-scale channels,mainly due to the instability of secondary flows within the inertial microfluidic chip.This study developed a microstructure-assisted ultra-low aspect ratio spiral microchannel,which utilized the stability and acceleration of secondary flows to achieve inertial particle focusing.The research results demonstrated successful particle focusing within a 1 mm-wide spiral channel chip,for different diameter sizes(7.3 μm and 15.5 μm),within a wide range of flow rates(0.5-3 mL/min).The focusing efficiencies for these particles were measured to be above 94%and 99%,respectively.Additionally,it was observed that the particle focusing position was approximately 100 μm away from the channel walls,significantly larger than other inertial focusing chips.Consequently,by incorporating ordered microstructures within the spiral channel chip,the stability and enhancement of secondary flows were achieved,resulting in flow rate and particle size-insensitive inertial focusing.Compared to traditional methods of inertial focusing,this design had advantages of not requiring additional sheath flow operations,and boasted high throughput and ease of manufacturing.This innovative structure opened up vast prospects for the development of portable inertial microfluidic chips,and could be used in the fields such as cell analysis and detection,flow cytometry,and online sample processing.

Carboxylated pillar[5]arene functionalized silver nanoparticles(CP5A-AgNPs)were successfully prepared by Creighton method.The prepared CP5A-AgNPs composites were characterized by ultraviolet-visible absorption spectroscopy(UV-Vis),infrared spectroscopy(FT-IR)and transmission electron microscopy(TEM),etc.TEM results showed that when the molar ratio of CP5A to AgNO3 was 1:10,the prepared CP5A-AgNPs had good dispersion and uniform particle size,with an average particle size of 4.05 nm.The catalytic degradation ability of CP5A-AgNPs toward two kinds of organic dyes,Rhodamine B(RhB)and methyl orange(MO)was further investigated.The results showed that the degradation rates of these two dyes by CP5A-AgNPs were 99.91%and 98.83%respectively,and CP5A-AgNPs exhibited good cyclic catalytic ability.The catalytic efficiencies in the fifth cycle were 91.06%and 98.45%,respectively.In addition,the performance of functionalized silver nanoparticles using monomer compound of CP5(CMA)as stabilizer(CMA-AgNPs)was compared.The results showed that CP5A-AgNPs had strong catalytic degradation activity to RhB and MO,and had good recycling catalytic ability.

o-Phthalaldehyde(OPA)is a new type of chemical disinfectant widely used in medical institutions.The development of new efficient and convenient detection platforms or methods for OPA is of great significance.In this work,in two-dimensional photonic crystal(2DPC)hydrogel,a responsive 2DPC hydrogel was prepared by functionalizing the hydrogel with ethylenediamine(EDA)and embedding amino groups.The amino group on the polymer chain of 2DPC hydrogel reacted with OPA,and with the increase of OPA concentration,the crosslinking density of the hydrogel also increased,resulting in the volume phase transition of the hydrogel,e.g.,shrinkage phenomenon.In the meantime,the spacing of 2DPC microspheres gradually decreased,while the diameter of Debye diffraction ring gradually increased.The results showed that the change of particle size spacing had a good linear relationship with logarithm of concentration of OPA in the range of 101?106 nmol/L,with the detection limit of 0.21 nmol/L(3σ/k).Therefore,the amino functionalized photonic crystal hydrogel sensor could realize the quantitative detection of OPA.The method was simple with low cost,ease to operate and use.Then the practicability of this hydrogel sensor for real sample was verified in the diluted clinical disinfectant.The recoveries of OPA in the diluted disinfectant were 100%?103%,with a relative standard deviations of 1.8%?5.5%.The results proved that 2DPC hydrogel sensor could be used for detection of OPA in disinfectant used for clinical endoscopes and other instruments.

Lactic acid produced by muscles during exercise training is transported to the liver for metabolism through the bloodstream.In this process,the lactate acid level increases with the increase of exercise intensity,and the concentration of lactate acid in interstitial matrix of muscle tissues increases subsequently,leading to muscle fatigue.Transcutaneous electrical nerve stimulation(TENS)is a widely used medical method for muscle relaxation and improving peripheral blood circulation.To monitor the potential of TENS to alleviate muscle fatigue,this study adopted electrical impedance tomography(EIT)method to visualize the alleviating effect of TENS on muscle fatigue by detecting the tissue electrical characteristics response caused by the changes in blood lactate concentration,a biomarker of muscle fatigue.An experimental platform was thus constructed to mimic the changes of blood lactate concentration(Cbl)in the muscle tissue model,and to measure the trend of the spatial-mean conductivity((σ))in the mimic model during the Cbl change.The blood flow velocity was closely related to the metabolic rate of the lactate in the blood.TENS could speed up blood flow and effectively reduced the lactate accumulation in muscle tissue.However,too fast blood flow velocity was prone to cause secondary ventricular fibrillation disease,which threatened the safety of human life.To avoid this threat,a real-time blood flow velocity mimic platform was developed in this study to monitor the(σ)changes caused by the changes in blood flow velocity(vph)in the vicinity of mimic blood vessels.The correlations between Cbl vs(σ),and vph vs(σ)in the mimic muscle tissue were verified by Pearson test.Pearson correlation analysis results showed a positive correlation between Cbl and(σ)(r=0.9113,p<0.05),and betweenvph and(σ)(r=0.9782,p<0.001).The approach presented here quantitatively assessed the potential of TENS stimulation-induced changes in lactate concentration and blood flow velocity for alleviating muscle fatigue through(σ).

A a novel composite ZIF-8/MWCNT was synthesized by combining zeolitic imidazolate framework-8(ZIF-8)with multi-walled carbon nanotubes(MWCNT).The composite was modified on glassy carbon electrode(GCE)to obtain ZIF-8/MWCNT/GCE,which was served as an effective electrochemical sensor for detection of Pb2+ and Cd2+.Benefiting from the high electrical conductivity of MWCNT and the synergistic effect between ZIF-8 and MWCNT,ZIF-8/MWCNT showed excellent electrocatalytic activity in individual and simultaneous detection of Cd2+ and Pb2+.Under the optimized conditions,the linear ranges were 0.03?8.00 μmol/L and 0.03?6.00 μmol/L with corresponding limits of detection(S/N=3)of 0.019 and 0.035 μmol/L for individual detection of Cd2+and Pb2+,respectively.Whereas for simultaneous detection of Cd2+and Pb2+in their mixture solutions,the linear ranges were 0.03?5.00 μmol/L and 0.03?5.00 μmol/L with corresponding limits of detection(S/N=3)of 0.022 and 0.048 μmol/L,respectively.In addition,the sensor exhibited good stability,reproducibility and anti-interference ability.Moreover,the sensor showed good feasibility and accuracy for determination of Cd2+ and Pb2+ in actual river water samples with spiking recoveries of 98.1%?104.0%and 98.3%?102.2%,respectively.