Development Of Quantum Dots-doped Nanoparticles And Its Application In Immunoassays

Quantum dots(QDs)are semiconductor particles.They have been implemented in many fields since their discovery in the 1980s.In the biomedical field,quantum dots are more widely reported in vivo imaging,but it is less used in the field of in vitro diagnosis.Because of the colloidal nature of QD dispersions,their application in diagnostics has been less successful.Diagnostic applications require agents that are water-soluble and capable of biological conjugation,which QDs-being created by colloidal synthetic procedures—tend not to be,although several methods have been established to improve their water-solubility.Furthermore,QDs cannot be easily conjugated with amine-functional molecules using the common carbodiimide activator Herein,QDs-doped carboxylate-functionalized polystyrene nanoparticles(QPs)were prepared.A system for the simultaneous detection of cytokeratin-19 fragment(CYFRA 21-1)and carcinoembryonic antigen(CEA)using QD-encoded,polystyrene nanoparticle-based,lateral flow test strips(QPs-LFTS)and a QDs-doped,nanoparticles-based,near-infrared-initiated,chemiluminescent homogeneous immunoassay(QNiCA)for sensitive clinical detection of CEA have been fabricated respectively.Two lung cancer markers,CYFRA 21-1 and CEA in human serum,could be simultaneously detected in QPs-LFTS system.Under optimal conditions,the QPs-LFTS system exhibited a wide dynamic range for CYFRA 21-1(1.3-480 ng/mL)and CEA(2.8-680 ng/mL).The detection limits for CYFRA 21-1 and CEA were 0.22 and 0.21 ng/mL respectively,and both specificity and reproducibility were good.Furthermore,excellent correlations(n = 120,R2 = 0.9862,P<0.0001 for CYFRA 21-1;n = 70,R2 = 0.9509,P<0.0001 for CEA)were obtained between the QPs-LFTS and commercially available CLIA kits in clinical serum testing.The results indicate that this test system is highly efficient and is expected to be useful for early screening and prognosis evaluation for lung cancer patients.On the other hand,to sensitively detect carcinoembryonic antigen(CEA)in low-volume serum samples,we devised and fabricated a novel near-infrared-initiated chemiluminescent homogeneous immunoassay via QDs-doped nanoparticles(QNiCA).the QNiCA system exhibited a wide dynamic range for CEA(1.2-490 ng/mL).The determination of CEA in 25 ?h serum samples was demonstrated with sub-picomolar(46 pg/mL)detection limits using QNiCA.The recovery and reproducibility of the method were satisfactory.Furthermore,excellent correlations(R2 = 0.99718,n = 107)were obtained between QNiCA and commercially available chemiluminescence immunoassay kits used in clinical serum testing.In summary,based on the QDs-doped polystyrene nanoparticles,QPs-LFTS and QNiCA were developed and be used in detecting the concentration of CYFRA 21-1 and CEA in human serum.After evaluation,the indicators of QPs-LFTS and QNiCA reagents meet the requirements of clinical testing.Excellent correlations were obtained between our methods and similar imported reagents used in clinical serum testing.This study comprehensively and accurately elaborated that the quantum dots-doped polystyrene nanoparticles as the fluorescence marker can improve the detection sensitivity,expand linear range and improve detection efficiency.It demonstrated the feasibility of the QDs-doped nanoparticles to apply in the detection of clinical disease markers.Also,it manifests that these developed immunoassays are expected to be applied in basic research and clinical examinations after further optimization.