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Orthogonal Analysis of Functional Gold Nanoparticles for Biomedical Applications



De-Hao D. Tsai, Yi-Fu Lu, Frank W. DelRio, Tae Joon Cho, Suvajyoti S. Guha, Michael R. Zachariah, Fan Zhang, Andrew J. Allen, Vincent A. Hackley


We report a comprehensive strategy based on implementation of orthogonal measurement techniques to provide critical and verifiable material characteristics for functionalized gold nanoparticles (AuNPs) used in biomedical applications. Thiolated polyethylene glycol (SH-PEG)-conjugated AuNPs with different terminal groups (methyl-, carboxylic-, and amine-) were chosen as a model system due to their high relevancy in nanomedicine. Electrospray-differential mobility analysis, asymmetric-flow field flow fractionation, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, inductively coupled plasma mass spectrometry, and small-angle X-ray scattering were employed to provide both complementary and orthogonal information on (1) particle size and size distribution, (2) particle concentration, (3) molecular conjugation properties (i.e., conformation and surface packing density), and (4) colloidal stability. Samples were analyzed before and after ≈ 50 months of cold storage. Results show that SH-PEGs are stably conjugated on the surface of AuNPs to form a brush-like polymer corona. The surface packing density of SH-PEG is ≈ 0.42 nm-2 for the methyl-SH-PEG AuNPs, ≈ 0.26 nm-2 for the amine-SH-PEG AuNPs, and ≈ 0.18 nm-2 for the carboxylic-SH-PEG AuNPs prior to cold storage. By analyzing the change in particle size distribution and number concentration in solution following cold storage, the long term colloidal stability is shown to be substantially improved via functionalization with methyl-SH-PEG and carboxylic-SH-PEG. The work described here provides a generic strategy to track and analyze the material properties of functional AuNPs intended for biomedical applications, and highlights the importance of a multi-technique analysis. The effects of long term storage on the physical state of the particles, and on the stability of the ligand-AuNP conjugates, are employed to demonstrate the capacity of this approach to address critical issues.
Analytical and Bioanalytical Chemistry


gold nanoparticle, polyethylene glycol, functionalization, stability, biomedical, nanomedicine, cold storage, particle size, conjugation


Tsai, D. , Lu, Y. , DelRio, F. , Cho, T. , Guha, S. , Zachariah, M. , Zhang, F. , Allen, A. and Hackley, V. (2015), Orthogonal Analysis of Functional Gold Nanoparticles for Biomedical Applications, Analytical and Bioanalytical Chemistry, [online],, (Accessed July 14, 2024)


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Created September 10, 2015, Updated October 12, 2021