Gold Nanoparticles-Packed Microdisks for Multiplex

Raman Labelling of Cells

Peipei Zhanga, Junfei Xiaa, Zhibin Wanga, Jingjiao Guana,b,*

aDepartment of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State

University, Tallahassee, Florida, 32310, USA

bIntegrative NanoScience Institute, Florida State University, Tallahassee, Florida 32306, USA

Abstract

Micro/nanoparticles containing densely packed gold nanoparticles (AuNPs) possess unique properties potentially useful for various biomedical applications. The micro/nanoparticles are conventionally produced by the bottom-up methods, which have limited capability for controlling particle size, shape and structure. Here we report development of a top-down method that integrates layer-by-layer assembly and microcontact printing to fabricate disk-shaped microparticles named microdisks composed of densely packed AuNPs. The method allows for precise control of not only size, shape and structure of the microdisks but also amount of the AuNPs in the microdisks. The microdisks can be loaded with different Raman reporters to generate characteristic surface-enhanced Raman scattering spectra under the near infrared excitation over a centimeter-scale lens-sample distance. Moreover, the microdisks can be attached to single live cells. This microdisk platform holds potential for multiplex Raman labelling of therapeutic cells for in vivo tracking of the cells.
This technique promises to be useful for non-invasive tracking of cells based on Raman imaging. The ability to track therapeutic cells in vivo is useful for developing effective cell therapies. Existing cell-tracking techniques suffer from the need of ionizing radiation, use of toxic quantum dots, or limited capability for multiplex labelling. In contrast, the AuNPs are less toxic than the quantum dots. Raman imaging does not involve ionizing radiation and it allows superb multiplex capability because Raman spectra have narrow bandwidths and are highly material dependent. Therefore we believe that our microdisk platform is suitable for tracking cells based on Raman imaging. This study focuses on demonstrating the feasibility of multiplex Raman labelling of cells with the microdisks.