Locating Three-Dimensional Position of Deep-Seated SERS Phantom Lesions in Thick Tissues Using Tomographic Transmission Raman Spectroscopy.

Locating distinct objects within a thick scattering medium remains a long-standing challenge in the fields of materials science, health, and engineering. Transmission Raman spectroscopy (TRS) with the use of surface-enhanced Raman scattering (SERS) nanoparticles has proven to be an effective approach to detect deep-seated lesions inside thick biological tissues. However, it has not yet been proven to spatially locate deep lesions in three dimensions using optical modalities. Herein, we present the concept of tomographic TRS and report its successful use for accurately locating SERS nanoparticles in elongated rod-like thick tissues. Our work starts with theoretical simulations of Raman photon propagation in tissues. We discovered a linear relationship between the Raman spectral peak ratio and propagation distance of Raman photons in tissues, allowing us to predict the location of lesions tagged by SERS NPs. Based on this, we propose a two-step tomographic TRS strategy, which includes axial scanning and ring scanning. We demonstrate the robustness of our approach using ex vivo thick tissue (4.5 cm in thickness) and locate an embedded SERS phantom lesion, with a ring scanning step of 10-30°. We successfully locate multiple SERS phantom lesions in the ex vivo porcine muscle stack with high accuracy (absolute error of <2 mm). Our method is rapid, efficient, and of low cost compared to current tomographic medical imaging techniques. This work advances Raman techniques for three-dimensional positioning and offers new insights toward practical diagnosis applications.

Non-Invasive Detection, Precise Localization, and Perioperative Navigation of In Vivo Deep Lesions Using Transmission Raman Spectroscopy.

Non-invasive detection and precise localization of deep lesions have attracted significant attention for both fundamental and clinical studies. Optical modality techniques are promising with high sensitivity and molecular specificity, but are limited by shallow tissue penetration and the failure to accurately determine lesion depth. Here the authors report in vivo ratiometric surface-enhanced transmission Raman spectroscopy (SETRS) for non-invasive localization and perioperative surgery navigation of deep sentinel lymph nodes in live rats. The SETRS system uses ultrabright surface-enhanced Raman spectroscopy (SERS) nanoparticles with a low detection limit of 10 pM and a home-built photosafe transmission Raman spectroscopy setup. The ratiometric SETRS strategy is proposed based on the ratio of multiple Raman spectral peaks for obtaining lesion depth. Via this strategy, the depth of the phantom lesions in ex vivo rat tissues is precisely determined with a mean-absolute-percentage-error of 11.8%, and the accurate localization of a 6-mm-deep rat popliteal lymph node is achieved. The feasibility of ratiometric SETRS allows the successful perioperative navigation of in vivo lymph node biopsy surgery in live rats under clinically safe laser irradiance. This study represents a significant step toward the clinical translation of TRS techniques, providing new insights for the design and implementation of in vivo SERS applications.

Exploring in vitro release and digestion of commercial DHA microcapsules from algae oil and tuna oil with whey protein and casein as wall materials.

Microencapsulation is a promising technique to improve the bioavailability and mask the unpleasant smell of DHA oils. Yet, how the encapsulated DHA oils are 'released' and 'digested' within the gastrointestinal tract (GIT) and the effect of the wall material and source of DHA have been largely unknown. Here, two commercial DHA microcapsules from algae oil (A-DHA) and tuna oil (T-DHA) with 100% whey protein (WP) and 80% casein and 20% WP (C-WP) as wall materials were evaluated in vitro respectively. The release ratio was nearly linearly increased to 77.7% and 41.7% after the simulated gastric phase for T-DHA and A-DHA microcapsules, respectively. In contrast to A-DHA microcapsules for which the release of DHA approached equilibrium in the later intestinal phase, a decline in the release ratio was shown for T-DHA microcapsules perhaps due to the interaction of T-DHA with bile salts resulting in the formation of micelles. The more stable release behaviors might suggest a better performance of A-DHA coated by WP, which enables sustainable release during GIT digestion. This is supported by the better ability to resist gastric proteolysis for A-DHA microcapsules. Additionally, T-DHA (27.5%) showed a lower lipid digestibility than A-DHA (68.5%) in the end due to their structure difference. Significantly positive correlations were found for both microcapsules between DHA release ratio and protein hydrolysis. This study has provided quantitative information on the in vitro release and digestion of DHA microcapsules as influenced by the wall protein and DHA source. The findings are practically meaningful for future formulation of DHA microcapsules with controlled release rates at target sites of the GIT.

Performance Comparison between the Nanoporous NiO x Layer and NiO x Thin Film for Inverted Perovskite Solar Cells with Long-Term Stability.

The development of hole-transport layers (HTLs) that elevate charge extraction, improve perovskite crystallinity, and decrease interfacial recombination is extremely important for enhancing the performance of inverted perovskite solar cells (PSCs). In this work, the nanoporous nickel oxide (NiO x ) layer as well as NiO x thin film was prepared via chemical bath deposition as the HTL. The sponge-like structure of the nanoporous NiO x helps to grow a pinhole-free perovskite film with a larger grain size compared to the NiO x thin film. The downshifted valence band of the nanoporous NiO x HTL can improve hole extraction from the perovskite absorbing layer. The device based on the nanoporous NiO x layer showed the highest efficiency of 13.43% and negligible hysteresis that was better than the one using the NiO x thin film as the HTL. Moreover, the PSCs sustained 80% of their initial efficiency after 50 days of storage. This study provides a powerful strategy to design PSCs with high efficiency and long-term stability for future production.

Synthesis of Red Cesium Lead Bromoiodide Nanocrystals Chelating Phenylated Phosphine Ligands with Enhanced Stability.

Two new phosphine ligands, diphenylmethylphosphine (DPMP) and triphenylphosphine (TPP), were introduced onto cesium lead bromoiodide nanocrystals (CsPbBrI2 NCs) to improve air stability in the ambient atmosphere. Incorporating DPMP or TPP ligands can also enhance film-forming and optoelectronic properties of the CsPbBrI2 NCs. The results reveal that DPMP is a better ligand to stabilize the emission of CsPbBrI2 NCs than TPP after storage for 21 days. The increased carrier lifetime and photoluminescence quantum yield (PLQY) of perovskite NCs are due to the surface passivation by DPMP or TPP ligands, which reduces nonradiative recombination at the trap sites. The DPMP and TPP-treated CsPbBrI2 NCs were successfully utilized as red emitters for fabricating perovskite light-emitting diodes with enhanced performance and prolonged device lifetime relative to the pristine one.