Advancements in Chiral Nanocomposites for Sensing and Imaging

In the evolving field of nanotechnology, researchers are continually advancing the development of artificial chiral nanomaterials, which have garnered attention for their unique optical properties. Among these, circular dichroism (CD) stands out as a potent sensing technology due to its heightened sensitivity compared to traditional analytical methods. However, a notable limitation of CD is its inability to facilitate in-situ imaging in living organisms.

To bridge this gap, scientists have been actively preparing chiral nanocomposites that possess a broader range of biological functionalities. Despite these efforts, some nanocomposites face challenges in complex physiological environments, where their structural integrity may be compromised, leading to performance inconsistencies. Moreover, distinguishing analytes from similar interfering substances remains a significant obstacle, impacting the selectivity of detection methods.

A recent study published in Light: Science & Applications presents a novel approach by a team from the State Key Laboratory of Integrated Optoelectronics at Jilin University. Led by Professor Geyu Lu, the team introduced a dual-mode probe using a composite of upconversion nanoparticles (UCNPs) encapsulated with chiral copper oxide sulfide (CuxOS) nanoparticles within a zeolitic imidazolate framework-8 (ZIF-8). This innovative design allows for effective in vitro sensing of hydrogen sulfide (H2S) and provides advanced imaging capabilities in vivo.

The probe operates on the principle that the reduction of CuxOS in the presence of H2S affects both its absorption properties and CD signal. This reaction leads to measurable changes in the UCL and CD signals, thereby enabling accurate in vitro detection of hydrogen sulfide. Furthermore, the incorporation of UCNPs allows for monitoring biological processes in living tumor-bearing mice, making this composite a valuable tool for real-time bioimaging.

One of the key features of the UCNPs/CuxOS@ZIF design lies in its ability to mitigate interference from other substances in the detection environment. The ZIF-8 structure functions not only as a stabilizing shell for the composite but also as a gas molecular sieve, selectively allowing H2S molecules to penetrate while blocking irrelevant molecules. This selective permeability is crucial in maintaining the integrity of sensing performance.

The research team articulated this “selection” mechanism: “The realization of this ‘selection’ actually comes from ZIF-8… H2S molecules easily enter the inside of ZIF-8, while other molecules are isolated from the outside.” This design significantly reduces the effect of reductive agents like L-Cysteine and Glutathione, which could otherwise interfere with the probe’s signals.

Looking forward, the assembly methodology used in this chiral nanocomposite may pave the way for the development of various multifunctional chiral composites. The researchers suggest that with well-conceived designs, these materials may unlock new applications in biosensing, bioimaging, and biotherapy, thus expanding the potential of chirality in the biomedical field.

For further information, the details of this study can be found in the original publication: Yang Lu et al., “Upconversion-based chiral nanoprobe for highly selective dual-mode sensing and bioimaging of hydrogen sulfide in vitro and in vivo,” Light: Science & Applications (2024).