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@PHDTHESIS{Zhang:1026897,
author = {Zhang, Rui},
othercontributors = {Molto Pallares, Roger and Mottaghy, Felix},
title = {{E}ngineering gold nanoconstructs for photoacoustic
imaging},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2026-01044},
pages = {1 Online-Ressource : Illustrationen},
year = {2026},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2026; Dissertation, Rheinisch-Westfälische
Technische Hochschule Aachen, 2026, Kumulative Dissertation},
abstract = {Anisotropic gold nanoparticles possessing unique optical
properties and different surface curvature, have emerged as
attractive nanostructures in recent decades. Among them,
gold nanostars (AuNS) are of particular interest since they
hold distinct localized surface plasmon (LSP) resonances,
yielding strong light extinction and photothermal conversion
efficiencies. Their LSP bands can be centered in the
near-infrared (NIR) region of the spectrum, where light
penetrates deeper in tissues, by adjusting the AuNS
morphology, such as branch number and aspect ratio. Thereby,
AuNS have been explored as optical diagnostic and
therapeutic agents for photoacoustic (PA) imaging and
photothermal therapy. However, the growth of anisotropic
gold nanoparticles often relies on cytotoxic shape-directing
agents, such as cetyltrimethylammonium bromide (CTAB),
raising safety concerns. Furthermore, those reagents tend to
strongly bind to the nanoparticle surface, hindering further
surface functionalization and limiting their biomedical
applications. In recent years, alternative shape-directing
agents, such as Good’s buffers, have been explored to
overcome these problems. Good’s buffers are biocompatible
and widely used in cell and tissue cultures. Moreover, they
can reduce gold salts to metallic gold and promote
star-shaped nanoparticle growth in absence of
pre-synthesized seeds. This approach is relatively simple,
nevertheless, variations in the precursor concentrations
(Au3+ and Good’s buffers), pH, temperature, and agitation
(stirring or vortex) can largely influence the AuNS growth,
leading to high polydispersity and batch-to-batch
variability. Hence, in my first study, I assessed the impact
of experimental factors’ first- and second-order
interactions on the seedless growth of HEPES-mediated AuNS
through a fractional factorial design of experiments. My
findings explain inconsistencies in previous literature and
highlight that simultaneous changes of two factors
(secondary interactions) can cause greater effects than the
sum of individual factor changes. Additionally, Good’s
buffers-mediated AuNS display the key features desired for
PA imaging, including strong NIR extinctions and large
photothermal conversion efficiencies. Nevertheless, no
systematic study had explored the construction of PA imaging
probes with Good’s buffer-mediated AuNS. In my second
study, I engineered the structure of AuNS by functionalizing
them with (pre-)clinical polymers and explored their
performance as PA probes in vitro and ex vivo. This study
highlights the potential of gold nanoconstructs as PA probes
and brings new insights into rational designs of nanoagents
for diagnostic applications. Beyond these two main studies,
my PhD research also focused on: 1. Investigating the AuNS
resilience to thermal deformation by monitoring their
reshaping dynamics with environmental transmission electron
microscopy (TEM). By tracking the thermal reshaping of
Good’s buffers (HEPES, EPPS, and MOPS)-mediated AuNS under
in-situ heating TEM, we revealed and compared the
deformation behaviors of the three AuNS under local
(photo-)thermal conditions, as those obtained in
photoacoustic and photothermal applications. This study
characterized the response of individual nanoparticles to
changes in the local environment and paved our way to
improve the thermal stability of gold nanoconstructs. 2.
Developing silver nanostructures (spheres, plates, and
cubes) for PA imaging, expanding their applications beyond
most common uses, such as antimicrobial and wound healing.
This study demonstrated the capabilities of (anisotropic)
silver nanoparticles, including a few therapeutic
formulations being investigated in clinical trials, as PA
imaging agents, which may offer new opportunities in
image-guided therapy.},
cin = {811003-3 ; 924210},
ddc = {610},
cid = {$I:(DE-82)811003-3_20140620$},
pnm = {JPI019-20 - Dr. Roger Molto Pallares (EXS-JPI-JPI019-20) /
VCI 661695 - Engineering Gold Nanoparticles Assemblies for
Quantification of Gadolinium-based Contrast Agents (661695)
/ Junior Principal Investigator Fellowship / Excellence
Strategy},
pid = {G:(DE-82)EXS-JPI-JPI019-20 / G:(VCI)661695 /
G:(DE-82)EXS-JPI / G:(DE-82)EXS},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2026-01044},
url = {https://publications.rwth-aachen.de/record/1026897},
}
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