Design And Applications Of Simple Smartphone-Based Fluorescent Detection Device And Method

With the rapid development of science and technology,a smartphone usually equips with high-resolution touchscreens,powerful processor,varieties of sensors and APP softwards,togather with powerful capabilities in data analysis and signal transmission.Now,a smartphone are been becoming a more and more powerful technique platform.The smartphone-based analytical devices and method have attracted much attention.In this thesis,we developed the applications of smartphone in fluorescent and resonance light scattering measurements,focusing on the ratiomeric brightness in a dual-channel design to improve the stability of response signals.The detailed contents are listed as follows:1.A smartphonebased ratio fluorescence detection device for immuno detection of carcinoembryonic antigenSensitive detection of cancer biomarkers is valuable for clinical diagnosis and treatment assessment of cancers.Fluorescent method is the one most commonly used in immunoassay due to its high sensitivity.But a fluorophotometer is usually expensive and cumbersome.Herein,we report a simple smartphone-based double-channel fluorescence detection setup for immunoassay.Except the smartphone,the total cost of the detection device itself is about 500?,including a laser pointer,a twinning cuvette,a collective lens,and an outside box.The fluorescence images of the sample and reference areas were captured by the camera in the smartphone.The brightness ratio was calculated using a user-edited smartphone APP software.By using 2,3-diaminophenazine?DAP?as the model luminophore,the influence of exposure time and photosensibility?ISO?on the sensitivity was tested.The brightness ratio offers high stability of the fluorescence signal,which is helpful to improve the sensitivity.The applicability of this device was demonstrated by a catalytic fluorimetric method for Cu²⁺determination,which is based on the oxidation of o-phenylenediamine?non-fluorescent?to DAP?strong fluorescent?by dissolved oxygen using Cu²⁺as the catalyst.Under the optimized experimental conditions,the limit of detection to Cu²⁺is 0.03 nmol/L.Accordingly,by using a CuS nanoparticle-conjugated second antibody as the signal tag,this catalytic fluorimetric method was applied in immunoassay.After the immune recognition,the CuS in the sandwich immuno-complex was dissolved by acid.The fluorescent signal was measured to quantify the amount of the target antigen.Under the optimized experimental conditions,limit of detection to carcinoembryonic antigen is 0.05 pg/mL.2.A double-channel smartphone-based resonance light scattering setup for immunoassay of alpha fetoprotein using PbS nanoparticles as signal tagResonance light scattering?RLS?,as a kind of elastic scattering,is produced when the incident beam is close to the molecular absorption of particles.The RLS technique has attracted considerable attention because of its remarkable advantages,such as rapidness,high sensitivity,and convenience in performance.Herein,a simple double-channel smartphone-based RLS detection device was developed for immunoassay.The RLS intensity was calculated by a user-edited APP software from images captured by the camera in smartphone.By using the brightness ratio between the sample and reference channels,the influence of the variation from the light source intensity drift,as well as the shooting parameters,can be eliminated efficiently.In the presence of ascorbic acid,Pb²⁺and I^-are reacted to form[Pb I₄]^2-,which can bond to cationic surfactant ion?cetyltrimethyl ammonium,CTA?to form an ion-association of[CTA]₂[PbI₄],which is strong RLS and can be used for Pb²⁺detection.Under the optimized experimental conditions,the limit of detection to Pb²⁺is 0.7?g/L.By using PbS nanoparticles conjugated second antibody for signal amplification,a sensitive immunoassay was developed.After the immune recognition,the PbS in the sandwich immuno-complex was dissolved by acid.The RLS signal is measured to quantify the amount of the target antigen.Under the optimized experimental conditions,limit of detection for alpha fetoprotein is 0.1 pg/m L.This smartphone-based DLS device offers the advantages of simple,inexpensive and miniaturization.3.Smartphone-based double-channel fluorescent ratiometic method for field determination of Cu²⁺in river water with improved accuracyCopper is a heavy metal element,which is an essential element for the organism.But at high concentration level,copper may cause serious harm to the organism.Hence,it is valuable to establish a sensitive detection method for Cu²⁺in environmental water samples.In this work,we developed a fluorescent setup and method for the rapid field analysis of copper ions in environmental water samples.The smartphone-based fluorescent measuring device offers the advantages of miniaturization,portability,and anti-interference ability,which is suitable for the field analysis.Except the smartphone,the total cost of the detection device itself is about 750?,including a 365 nm LED flashlight and lithium battery,quartz twin cuvette,collective lens,filter,and outside box.Based on the fluorescence quenching effect of Cu²⁺to the luminophore of N-doped carbon quantum dots,a ratiometic fluorescent method was developed for field determination of Cu²⁺in real water samples.The fluorescent images in the sample and reference areas were captured by the camera in a smartphone,and their brightness ratio was calculated by a user-edited APP softward and used as the signal indictor.It was shown that brightness ratio is insensitive the variation in light source intensity,shooting parameters and focus of the camera,and ambient temperature,which is helpful to improve the stability and reliability of the simple portable detection device.By using a balanced calibration method with three standard solutions,the accuracy for concentration determination is improved further.Under optimized conditions,the proposed method was applied to detect Cu²⁺in the range from 1 to 200 nmol/L with the detection limit of 0.5nmol/L.