Eutectic gallium indium (EGaIn), a Ga‐based liquid metal alloy holds great promise for designing next‐generation core–shell nanoparticles (CSNs). A shearing‐assisted ligand‐stabilization method has shown promise as a synthetic method for these CSNs; however, determining the role of the ligand on stabilization demands an understanding of the surface chemistry of the ligand–nanoparticle interface. EGaIn CSNs are created and functionalized with aliphatic carboxylates of different chain length, allowing a fundamental investigation on ligand stabilization of EGaIn CSNs. Raman and diffuse reflectance Fourier transform spectroscopies (DRIFTS) confirm reaction of the ligand with the oxide shell of the EGaIn nanoparticles. Changing the length of the alkyl chain in the aliphatic carboxylates (C2–C18) may influence the size and structural stability of EGaIn CSNs, which is easily monitored using atomic force microscopy (AFM). No matter how large the carboxylate ligand, there is no obvious effect on the size of the EGaIn CSNs, except the particle size getting more uniform when coated with longer chain carboxylates. The AFM force–distance measurements are used to measure the stiffness of the carboxylate‐coated EGaIn CSNs. In corroboration with DRIFTS analysis, the stiffness studies show that the alkyl chains undergo conformational changes upon compression.
Developing
a cancer theranostic nanoplatform with diagnosis and
treatment capabilities to effectively treat tumors and reduce side
effects is of great significance. Herein, we present a drug delivery
strategy for photosensitizers based on a new liquid metal nanoplatform
that leverages the tumor microenvironment to achieve photodynamic
therapeutic effects in pancreatic cancer. Eutectic gallium indium
(EGaIn) nanoparticles were successfully conjugated with a water-soluble
cancer targeting ligand, hyaluronic acid, and a photosensitizer, benzoporphyrin
derivative, creating EGaIn nanoparticles (EGaPs) via a simple green
sonication method. The prepared sphere-shaped EGaPs, with a core–shell
structure, presented high biocompatibility and stability. EGaPs had
greater cellular uptake, manifested targeting competence, and generated
significantly higher intracellular ROS. Further, near-infrared light
activation of EGaPs demonstrated their potential to effectively eliminate
cancer cells due to their single oxygen generation capability. Finally,
from in vivo studies, EGaPs caused tumor regression
and resulted in 2.3-fold higher necrosis than the control, therefore
making a good vehicle for photodynamic therapy. The overall results
highlight that EGaPs provide a new way to assemble liquid metal nanomaterials
with different ligands for enhanced cancer therapy.
Dye-pretreated
anatase TiO2 films, commonly used as
photoanodes in dye-sensitized solar cells, were utilized as a model
system to investigate the laser-induced anatase to rutile phase transformation
(ART), using N719 dye, N749 dye, D149 dye, and MC540 dye as photosensitizers.
The visible lasers (532 and 785 nm) used for Raman spectroscopy were
able to transform pure anatase into rutile at the laser spot when
excitation of the dye sensitizer caused an electron injection from
the excited state of the dye molecule into the conduction band of
TiO2. The three dyes with carboxylic acid anchor groups
(N719, N749, and D149 dyes) experienced ART upon dye excitation; diffuse
reflectance infrared Fourier transform spectroscopy (DRIFTS) and Raman
spectra validated that these dyes were chemisorbed to the semiconductor
surface. The MC540 dye with a sulfonic acid anchor group did not experience
ART, and the DRIFTS and Raman spectra were inconclusive about the
chemisorption of this dye to TiO2. A TiO2 calibration
curve and percent rutile contour plots developed for this project
are able to quantify the amount of rutile created at the surface of
the samples. These improved chemical images which map rutile concentration
help to visualize how ART propagates from the center of the laser
spot to the surroundings. Factors such as visible-light absorption
and anchor groups that covalently bind to the semiconductor play a
key role in effective laser-induced ART.
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