Depolarized dynamic light scattering nanosensing based on aggregation-induced slowing-down of nanoparticles rotational diffusion

• Published in: Laser physics letters 2019-10, Vol.16 (10), p.106001
• Main Authors: Levin, Alexander D, Alenichev, Mikhail K, Nagaev, Alexander I, Drozhzhennikova, Ekaterina B, Grigorenko, Vitaly G, Andreeva, Irina P, Kostrikina, Eugenia S
• Format: Article
• Language: English
• Subjects: autocorrelation function; depolarized dynamic light scattering (DLS); nanoparticles aggregation; optical nanosensor; rotational diffusion
• ISSN: 1612-2011; 1612-202X
• DOI: 10.1088/1612-202X/ab3f9f

The intensity fluctuations of the depolarized component of laser light scattered by the optically anisotropic nanoparticles contain significant information on the rotational diffusion of particles. A high size-sensitivity of nanoparticle rotational diffusion in solution has a potential for monitoring of the biospecific aggregation of functionalized nanoparticles for biosensing applications. Here we demonstrate a new approach for determination of the target analytes such as proteins and other biomolecules using optical nanosensors based on dynamic light scattering (DLS). The proposed detection principle is based on the significant decrease of the rotation diffusion coefficient due to the nanoparticle aggregation. The decrease of the rotational diffusion is measured using intensity autocorrelation functions (IACF) from partially depolarized DLS. The criteria of the relative decrease of the rotational diffusion using the difference of IACF integrals from blank and analyte are proposed. The nanosensor prototypes based on gold nanospheres functionalized by antibodies to cancer markers were designed and validated using the proposed principle. Significant improvement of the sensor sensitivity as compared with the conventional hydrodynamic diameter determination was demonstrated.