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Page 10 of 33 Mao et al. Chem Synth 2023;3:26 https://dx.doi.org/10.20517/cs.2022.41

Hybrid structure
Heavily-doped semiconductor nanometer materials also exhibit strong LSPR absorbance when combined
with the plasmonic metal NCs. The copper chalcogenides have promising potential for use in photothermal of
therapy (PTT) [84-86] applications. Zhu et al. and Liu et al. synthesized Au-Cu Se nanocrystals, which
2-x
combined heavily doped p-type semiconductor and noble metal domains [85,87] . They reported a novel type
multiphase nanoparticles (NPs) consisting of a heavily doped p-type Cu Se and an Au domain (n-type
2-x
feature), as shown in Figure 6A and B. This nanocrystal exhibited a broad LSPR absorption region across
visible to NIR absorption wavelengths and demonstrated strong interactions between the two nanocrystal
domains , as depicted in Figure 6C.
[87]

BIOLOGICAL APPLICATION
The particular applications of NPs have attracted increasing attention from scholars with the speedy a
development of nanotechnology, materials science, and molecular imaging. They have brought great
convenience for us to observe the situation in real-time in vivo as a clinical detection and research tool. As
type of nanomaterial, contrast agents can visualize the physiological structures in organisms. In recent years,
researchers have found that nanomaterials can provide high-resolution and high-contrast images for the
visualization of precision medicine delivery, which plays a crucial role in imaging applications. Among
them, copper-based chalcogenide compounds present unique advantages with strong NIR LSPR absorption in
feature , attracting significant attention for photothermal-guided biological applications [88-90] . There are
[74]
several strategies to improve photothermal conversion efficiency. (1) Changing the carrier concentration
the doped semiconductor to increase the possibility for non-radiation transition (usually released as heat
[91]
energy). (2) Manipulating the crystal phase, morphology, and particle size of Cu S nanocrystals to modify
2-x
the LSPR absorption feature . (3) Forming the hybrid structure by increasing the cross-section
[92]
absorption .
[93]

In this direction, we describe the application of copper chalcogenide NCs from biosensing to in vivo
imaging and therapy. The main in vivo imaging functions of nano-copper sulfide include computed
tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography
(SPECT)/CT, fluorescence imaging (FLI), and PA imaging. Some researchers enhanced copper
chalcogenide NCs with fluorescent molecules, such as indocyanine green (ICG), and luminous
nanoparticles, such as quantum dots (QDs), upconversion nanoparticles, and radioactive isotopes. These
enhancements may provide additional imaging choices. The utilization of copper sulfide NCs in tumor
therapy includes PTT, chemodynamic therapy (CDT), photodynamic therapy (PDT), immunotherapy (IT),
radiation therapy (RT), and multimodal combination therapy. Most of the treatment strategy is mainly
based on the response of nanomaterials to stimuli, which can elicit an immune response and attract
apoptosis or death of tumor cells.

Biosensing
Heavily-doped copper chalcogenides, as p-type plasmonic materials, were wildly used in biosensing. In the
past few decades, copper chalcogenides have attracted significant attention due to their unique
characteristics as both metals and semiconductors [94-97] . Several studies have proven that Cu S exhibited ,
]
2-x
broad-band LSPRs in the NIR region and fundamentally altered light-matter interactions. These
characteristics have led to a wide range of applications, including enhanced spectrum , sensing [99
[98]
photocatalysis [100,101] , and optical devices . 3+
[102]
to
In Figure 7A, Zhou et al. reported a core-shell composite material named mCu S@SiO @-Y O :Yb /Er of
3+
2
2-x
3
2
for the fingerprint recognition. As shown in Figure 7B, the color of the material changed from green
orange with increasing excitation power. This study opened up new ideas for the design and preparation