Construction And Environment Analysis Application Of Cloth@Paper Based Microfluidic Analytical Platform

The coastal zone is the first marine economic zone where sea and land interact.Nowadays,coastal zones face especially severe pressure brought by human activities.Heavy metal and antibiotic pollution in coastal waters has attracted much attention.The development of reliable detection methods for low content of heavy metals and antibiotics in water bodies has become an important content of environmental analysis and monitoring,as well as a research hotspot in the field of water pollution control.Common large fixed instruments are limited by time-consuming analysis process,expensive instruments and the need for trained operators in the monitoring of water pollutants.The research and development of portable,simple,sensitive and reliable rapid detection technology has become a hot spot in the field of environmental monitoring.Among which,microfluidic analytical technology has attracted much attention.Paper-based microfluidic analytical device（μPAD）is a low-cost,efficient and convenient analytical platform in which fluids could be transported only by capillary forces,avoiding the use of extra flow transport control pumps and other peripherals.μPAD can meet the needs of cheap,rapid field detection in low resource configurations.In aμPAD,it is necessary to modify the detection area with functional materials to form sensing base and establish sensing mechanism.Most surface modification reactions need to be carried out in a solution.However,the strength of paper will decrease when soaked in solution for a long time.Thus,paper cannot withstand slightly intense experimental operations such as agitation.This will greatly limit the complex,multi-step modification reactions of advanced functional materials on paper,thus restricting the integration of sensing mechanisms onμPADs.Cloth@paper based microfluidic analytical device（μCPAD）is proposed for the first time in this paper.The cloth-based sensing component is used as the detection area on theμPAD,effectively breaking the restriction of the limited modification of paper on the establishment of the sensing mechanism.By taking advantage of the convenient surface modification of the cloth,the ion or molecular imprinting technology-assisted fluorescence sensing mechanism was integrated on the cloth by multi-step grafting reaction.Thereby,a series ofμCPADs with high sensitivity and good selectivity were prepared and applied to the analysis of typical environmental pollutants such as heavy metals.The main research results are briefly introduced as follows.1.Construction of cloth@paper microfluidic analytical device and application for ion imprinting technology-assisted fluorescence sensing of Cr（VI）.A rotaryμCPAD that can realize the four-set multiplexed detection of Cr（VI）,with each set providing three parallel measurements was designed and produced.By rotating the bottom layer,a single sensing position is exposed to the detection port in turn to collect fluorescence signals.Twelve sensing positions are composed of Cr-IIP cloth-based fluorescence sensing components that were prepared by grafting Cd Te quantum dots and then modified with Cr-IIP via surface imprinting technology.The IIP fluorescence sensingμCPAD has high selectivity and sensitivity of Cr（VI）detection,with the imprinting factor of 3.89 and the detection limit（LOD）of 0.26μg/L.Furthermore,theμCPAD obtained high recoveries in the range of 97.06～114.05%in river water and seawater samples.2.Construction of rotary cloth@paper microfluidic analytical device and application for ion imprinting technology-assisted simultaneous fluorescence sensing of Pb²⁺and Hg²⁺.A rotaryμCPAD that can simultaneously detect two ions in four samples was designed and produced.By rotating the top layer clockwise,four lead ion sensing sites can be exposed to corresponding detection ports to collect fluorescence signals.By rotating the top layer counterclockwise,fluorescence signals of four mercury ion sensing sites can be collected.The sensing sites are composed of Pb-IIP or Hg-IIP cloth-based fluorescence sensing components.The rotary IIP fluorescence sensingμCPAD obtained high sensitivity for Hg²⁺with the LOD of 0.18μg/L and the imprinting factor of 5.38,as well as the LOD of Pb²⁺was 0.07μg/L and the imprinting factor was 2.73.Furthermore,the results of Pb²⁺and Hg²⁺in river water and seawater detected by theμCPAD were consistent with those of ICP-MS,with satisfied recoveries in the range from 96.18～114.08%.3.Construction of rotary cloth@paper microfluidic analytical device and application for ion imprinting technology-assisted metal-organic framework fluorescence sensing of Cu²⁺.An origamiμCPAD that could provide two parallel detection results was designed and produced.The both sensing sites were cloth-based fluorescence sensing components with Cu-IIP NH₂-MIL-101（Fe）as the detection signal source.It was the first attempt to prepare ion imprinting technology-assisted metal-organic framework cloth-based fluorescence sensing components by one-step solvothermal method and ion imprinting technology,and finally used to fabricate theμCPAD.The Cu-IIP assisted metal-organic framework fluorescence sensingμCPAD obtained high sensitivity of Cu²⁺with the LOD of 0.042μg/L.Furthermore,the detection results of Cu²⁺in lake and river water were consistent with those of ICP-MS with satisfied recoveries in the range of 98.37～103.70%.4.Construction of origami cloth@paper microfluidic analytical device and application for molecular imprinting technology-assisted metal-organic framework fluorescence sensing of tetracycline.An origamiμCPAD that could provide three parallel detection of two samples was designed and produced to realize the selective,sensitive and high-throughput detection of tetracycline by the origami-assisted sampling and fluorescence detection.The six sensing sites were cloth-based fluorescence sensing components（MIP@NH₂-MIL-53（Al）@cloth）with NH₂-MIL-53（Al）as the detection signal source.MIP@NH₂-MIL-53（Al）@cloth were prepared by one-step solvothermal in-situ self-assembly of NH₂-MIL-53（Al）and then imprinted with tetracycline MIP on its surface.The MIP assisted metal-organic framework fluorescence sensingμCPAD obtained high sensitivity of tetracycline with the LOD of 0.039μM.Furthermore,theμCPAD obtained satisfied recoveries in the range of 98.69～108.70%in river water and seawater samples.In summary,the low cost,sensitive and selectiveμCPADs were constructed,with cloth-based sensing components as the detection area on theμPAD.TheμCPADs successfully realized the efficient and sensitive detection of hexavalent chromium,lead ions,mercury ions,copper ions and tetracycline,providing a diversified and flexible integrated platform for the detection of environmental pollutants.