Matrix Effect Of Swine Urine On Colloidal Gold And Time-Resolved Fluorescent Nanobeads Immunochromatographic Assay

Immunochromatographic assay(ICA)is a rapid,convenient,and low-cost analytical technique for detection of targets on-site,which has been widely used in food safety field.However,an important issue to be addressed for this method is matrix effect from different samples.In this work,colloidal gold ICA(CG-ICA)and timeresolved fluorescent nanobead ICA(TRFN-ICA)were developed to detect clenbuterol in swine urine.The matrix effect on TRFN-ICA and CG-ICA was systematically assessed in swine urine samples.In this work,the ICA based on colloidal gold was developed for detection of clenbuterol(CLB).Under the optimized conditions,the limit of detection(LOD),the linear range and half inhibition concentration(IC50)of CG-ICA for detection of CLB were 68 pg/mL,80~2000 pg/mL,and 417 pg/mL,respectively.Subsequently,the effect of the swine urine on the CG-ICA was evaluated by adding the standard solution of CLB to Phosphate-buffered saline(PBS)and different swine urine samples at 800 pg/mL.The detection result of PBS and different swine urine samples were 772 pg/mL and 383~1263 pg/mL,respectively.Meanwhile,standard curves were established based on PBS and different swine urine samples.The result showed that the sensitivity of CG-ICA obviously decreased with swine urine samples,while the linear range of CG-ICA became narrower as well.The TRFN-ICA based on time-resolved fluorescent nanoparticle was developed for detection of CLB by using time-resolved fluorescent reader to obtain signal intensity of test line(T line)and control line(C line).The pH of the TRFN solution,the concentration of the antibody conjugating TRFN,the concentration of detective antigen immobilized on the T line,and the detection time were optimized in this work.Under optimized conditions,the LOD,IC50,and linear range of TRFN-ICA for detection of CLB were 16 pg/mL,308 pg/mL,and 40~2000 pg/mL,respectively.Subsequently,the effect of the swine urine on the TRFN-ICA was evaluated by adding the standard solution of CLB to PBS and different swine urine samples at 800 pg/mL.The detection result of PBS and different swine urine samples were 735 pg/mL and 21~4264 pg/mL,respectively.Meanwhile,standard curves were established based on PBS and different swine urine samples.The result showed that the sensitivity of TRFNICA obviously decreased with swine urine samples,while the linear range of TRFNICA became narrower as well.Compared the data between CG-ICA and TRFN-ICA for detection of CLB in swine urine,we found that TRFN-ICA owned better sensitivity(16 pg/mL),shorter detect time(10 min),and less antibody(7 ?g/mL).While CG-ICA has better stability and better anti-interference ability.Effect of swine urine samples on CG-ICA and TRFN-ICA was systematically studied in this work.The study could provide,a useful basis for the research of ICA based on different probes.