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This paper reviews the synthesis and biomedical applications of bismuth complexes with unusually low toxicity and excellent clinical performances, summarizes their main synthesis methods, and biomedical applications as drugs for the therapeutic treatment of gastrointestinal disease, Helicobacter pylori infection, and various cancers; especially, describes the development of bismuth-based MOFs in the drug delivery and potential application in cancer treatment. *Corresponding authors.A variety of bismuth complexes have been extensively explored in biomedical applications. The well-known low toxicity and environmental friendliness of bismuth salts make them valuable for large-scale synthesis of various bismuth-based complexes, which become more significant as active pharmaceutical ingredients of medical products. Bismuth complexes have been widely and preferably used in biomedicine with satisfactory therapeutic effect, which is highlighted in this review. However, their synthesis methods have been scarcely summarized. The classification of the main synthesis methods of bismuth complexes has been done here, followed by updates of the relevant advances concerning applications in biomedicine such as therapeutic effect on gastrointestinal diseases, antimicrobial, and anticancer activities, and the description of the side effect and biotoxicity resulting from long-term use of bismuth as well. Bismuth containing metal-organic frameworks, newly developed bismuth-based materials, are also discussed here, becoming a hot research topic recently. An outlook for future study on the potential use of bismuth complexes in biomedicine is provided in the end.

Significance: Optical coherence tomography (OCT) has proven useful for detecting various oral maxillofacial abnormalities. To apply it to clinical applications including biopsy guidance and routine screening, a handheld imaging probe is indispensable. OCT probes reported for oral maxillofacial imaging were either based on a bulky galvanometric mirror pair (not compact or long enough) or a distal-end microelectromechanical systems (MEMS) scanner (raised safety concerns), or adapted from fiber-optic catheters (ill-suited for oral cavity geometry). Aim: To develop a handheld probe featuring great compactness and excellent maneuverability for oral maxillofacial tissue imaging. Approach: A dual-axis MEMS scanner was deployed at the proximal end of the probe and the scanned beam was relayed to the distal end through a 4f configuration. Such design provides both a perfect dual-axis telecentric scan and excellent compactness. Results: A handheld probe with a rigid part 70 mm in length and 7 mm in diameter and weighing 25 g in total was demonstrated through both ex vivo and in vivo experiments, including structural visualization of various oral maxillofacial tissues and monitoring the recovery process of an oral mucosa canker sore. Conclusions: The proposed probe exhibits excellent maneuverability and imaging performance showing great potential in clinical applications.

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Proton exchange membrane fuel cells (PEMFCs) are promising energy conversion devices due to their high efficiency, high energy density and low operation conditions. Pt nanoparticles are widely used as the catalysts in cathode and anode for the half cell reactions. However, the durability of Pt nanoparticles still remains the most significant obstacle for large scale application of PEMFCs, especially in the cathode. In general, a significant decrease in electrochemical surface area (ECA) is observed.In this work, five membrane electrode assemblies (MEAs) with platinum (Pt) nanoparticles of different average sizes (2.2, 3.5, 5.0, 6.7, and 11.3 nm) in the cathode were analyzed before and after potential cycling (0.6 to 1.0 V, 50 mV/s). MEAs with 2.2nm and 3.5nm show significant growth in mean particle sizes after 10,000 potential cycles, while the other samples do not (Fig.1a).To understand the aforementioned particle growth, we need to consider the following possible mechanisms: (i) modified electrochemical Ostwald ripening (MEOR), (ii) platinum dissolution and re-precipitation inside the membrane and (iii) particle migration and coalescence. As MEOR is an isotropic process, a comparison of the particle size distributions (PSDs) of spherical particles and PSDs of all the particles indicates that this mechanism plays a significant role in the degradation of 2.2nm and 3.5nm samples, but not in the other samples (Fig.1b). Re-precipitated particles in the membrane are found among almost all the samples (Figure 2a-e), but their amount is minor comparing to the particles in the cathode, which reveals that re-precipitation plays an insignificant role in the degradation of PEMFCs. In terms of coalescence there are three plausible mechanisms: (i) particles migrate and coalescence, (ii) particles in proximity grow in size due to MEOR and make contact and (iii) soluble Pt species re-precipitate to bridge two particles followed by MEOR (Figure 3a). In any case, coalesced particles occur among all samples, although the 2.2nm sample shows the highest extent of coalescence (Fig.3b). However, as the carbon support exhibits a convoluted 3D structure, as shown by in-situ tomography (Fig. 3c,d), it is difficult for particles to coalesce through a migration mechanism.In summary, Pt dissolution seems to be the controlling mechanism for degradation, as it assists the MEOR process and two plausible mechanisms of coalescence. Thus, reducing Pt dissolution is essential to prevent ECA loss and catalyst performance degradation.

The electrocatalysis of Ag/Ni bimetallic alloys to glucose oxidation was studied. It was found that the presence of Ag and Ni in the alloys facilitates each other's electrocatalysis toward glucose oxidation, exhibiting an interesting synergistic effect. At about 0.7 V vs SCE, the electrocatalysis of Ag toward glucose oxidation was enhanced by Ni. However, it's very difficult to obtain stable response signals at this potential although a relatively large current response to glucose was observed. Similarly, the presence of Ag improved the Ni(OH) 2 /NiOOH mediated electrocatalytic oxidation of glucose at 0.45 V. By contrast, the Ag/Ni-deposited electrode responded rapidly to the changes of glucose concentration, producing stable signals within 4 s. Two linear ranges were identified with one at low glucose levels from 1 to 9.89 μM and the other at high glucose concentrations from 19.68 to 106.89 μM. The detection limit of the electrode is 0.49 μM. This study shows the potential to develop glucose based sensors or fuel cells.

Histopathological examination is still the gold standard for diagnoses of oral-maxillofacial lesions, but it is invasive and time-consuming. Optical coherence tomography (OCT) provides a kind of noninvasive, label-free, real-time and high-resolution imaging technology. In this study, in order to assess the feasibility of OCT in oral clinical application, fresh excised tissue specimens from 59 patients undergoing oral-maxillofacial surgery were imaged in detail by using a benchtop swept-source OCT system. It is shown that different lesions or tissues can be obviously distinguished based on their different microstructural features in OCT images, and the features are similar to those of their corresponding histopathological images. It is proven that OCT has great feasibility and potential as a diagnostic aid for surgeons in oral medicine.

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