P.I. Nikitin, N.V. Guteneva, V.A. Bragina, S.L. Znoyko, A.V. Orlov, B.G. Gorshkov, M.P. Nikitin
General Physics Institute, Russian Academy of Sciences,
Keywords: magnetic nanoparticles, immunoassay, cancer markers, cardiac markers
Summary:Magnetic nanoparticles (MP) have provided many breakthrough solutions for life science. The immense potential of MP as labels in advanced immunoassays stems from the fact that they, unlike optical labels, can be easily detected inside 3D opaque porous biosensing structures or in colored mediums, manipulated by an external magnetic field, exhibit high stability and negligible background signal in biological samples, etc. The combination of magnetic nanolabels with an original technique of their quantification have permitted development of novel multiplex methods of express biosensing, some of them cannot be realized with popular colored or florescent labels due to the new 3D architecture which goes beyond the traditional planar techniques. The developed electronic detection methods are based on the highly sensitive technique of magnetic particle quantification (MPQ) by non-linear magnetization [1-3]. Recently these methods were used for MPQ-cytometry development for rapid quantitative determination of the oncological status of cells, as well as for assessment of antigen expression on cell surfaces . A new generation of multi-channel MPQ readers has been developed that offer the record limit of detection (LOD) of 0.4 ng of MP in 0.2 ml volume within an extremely wide 7-order linear dynamic range [2,3]. In this research, four approaches to multiplex express biosensing have been demonstrated based on 1) one-run test on the surfaces of several 3D porous structures; 2) flat and micropillar microfluidic sensor chips; 3) multi-line lateral flow strips; 4) quick on-demand design based on modular architecture, which is the first 3D multiplexing method that goes beyond the traditional planar techniques. The 3D design of several spatially separated tests of different specificity and simultaneous volumetric detection of MP from all recognition zones essentially simplify the requirements related to cross-reactivity of the reagents and functionalized MP, with virtually no sacrifice in performance compared with the single-plex tests. Detection of cardiac and cancer markers, particular, of cardiac troponin I (cTnI) and prostate-specific antigen (PSA) as well as small molecules and oligonucleotides were used in the experiments. The LODs for detection of total PSA and cTnI in human serum was as good as 25 pg/ml and 12 pg/ml by dry-reagent magnetic lateral flow and express immunofiltration assays, respectively. The analytical characteristics of the developed multiplex methods are on the level of the modern time-consuming laboratory techniques while assay time is less than 30 min. The developed multiplex biosensing platforms are promising for medical and veterinary diagnostics, food inspection, environmental and security monitoring, etc. References: . M.P. Nikitin, V.O. Shipunova, S.M. Deyev, P.I. Nikitin. Nat. Nanotechnol. 9 (2014) 716-722. . A.V. Orlov, V.A. Bragina, M.P. Nikitin, P.I. Nikitin. Biosens. Bioelectron. 79 (2016) 423-429. . A.V. Orlov, S.L. Znoyko, V.R. Cherkasov, M.P. Nikitin, P.I. Nikitin. Anal. Chem. 88 (2016) 10419-10426. . V.O. Shipunova, M.P. Nikitin, P.I. Nikitin, S.M. Deyev. Nanoscale 8 (2016) 12764–12772.