Metal nanoclusters (NCs) with unique chemical and physical properties have been extensively demonstrated to be emerging nanoantibiotics for fighting bacterial infections. Understanding the antibacterial mechanisms of metal nanoclusters is important for evaluating their clinical applications as nanoantibiotics. To understand the antibacterial mechanism, gold nanoclusters (AuNCs) were applied as an antibacterial agent for real-time observations of their interactions with bacteria by in situ transmission electron microscopy (TEM). In this work, a surface ligand of glutathione-conjugated (GSH)-AuNCs was prepared via a simple hydrothermal method. Optical and structural characterizations validated the successful preparation of GSH-AuNCs. Bacterial growth curves of Acetobacter aceti revealed that the antibacterial activity of GSH-AuNCs increased with the weight concentration. The antibacterial activity of GSH-AuNCs was confirmed by the intracellular reactive oxygen species (ROS) generation induced by GSH-AuNCs in A. aceti. Furthermore, real-time observations of interactions between GSH-AuNCs and A. aceti were made using in situ liquid cell TEM. Based on the results of real-time observations, GSH-AuNCs first attached onto the bacterial membranes of A. aceti by physical adsorption and then penetrated into A. aceti by internalization. Eventually, the production of intracellular ROS induced by GSH-AuNCs caused destruction of the bacterial membranes, which led to the death of A. aceti. After the bacterial membranes had been destroyed, A. aceti eventually died.

Plasmonic nanomaterials have been intensively explored for applications in biomedical detection and therapy for human sustainability. Herein, plasmonic gold nanoisland (NI) film (AuNIF) was fabricated onto a glass substrate by a facile seed-mediated growth approach. The structure of the tortuous gold NIs of the AuNIF was demonstrated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Based on the ultraviolet-visible spectrum, the AuNIF revealed plasmonic absorption with maximum intensity at 624 nm. With the change to the surface topography created by the NIs, the capture efficiency of Escherichia coli (E. coli) by the AuNIF was significantly increased compared to that of the glass substrate. The AuNIF was applied as a surface-enhanced Raman scattering (SERS) substrate to enhance the Raman signal of E. coli. Moreover, the plasmonic AuNIF exhibited a superior photothermal effect under irradiation with simulated AM1.5 sunlight. For photothermal therapy, the AuNIF also displayed outstanding efficiency in the photothermal killing of E. coli. Using a combination of SERS detection and photothermal therapy, the AuNIF could be a promising platform for bacterial theranostics.

Inadequate sitting posture can cause imbalanced loading on the spine and result in abnormal spinal pressure, which serves as the main risk factor contributing to irreversible and chronic spinal deformity. Therefore, sitting posture recognition is important for understanding people’s sitting behaviors and for correcting inadequate postures. Recently, wearable devices embedded with microelectromechanical systems (MEMs) sensors, such as inertial measurement units (IMUs), have received increased attention in human activity recognition. In this study, a wearable device embedded with IMUs and a machine learning algorithm were developed to classify seven static sitting postures: upright, slump, lean, right and left bending, and right and left twisting. Four 9-axis IMUs were uniformly distributed between thoracic and lumbar regions (T1-L5) and aligned on a sagittal plane to acquire kinematic information about subjects’ backs during static-dynamic alternating motions. Time-domain features served as inputs to a signal-based classification model that was developed using long short-term memory-based recurrent neural network (LSTM-RNN) architecture, and the model’s classification performance was used to evaluate the relevance between sensor signals and sitting postures. Overall results from performance evaluation tests indicate that this IMU-based measurement and LSTM-RNN structural scheme was appropriate for sitting posture recognition.

Designing a facile and rapid detection method for haptoglobin (Hp) phenotypes in human blood plasma is urgently needed to meet clinic requirements in hemolysis theranostics. In this work, a novel approach to qualitatively analyze Hp phenotypes was developed using a fluorescent probe of gold nanoclusters (AuNCs). Hemoglobin-conjugated (Hb)-AuNCs were successfully synthesized with blue-green fluorescence and high biocompatibility via one-pot synthesis. The fluorescence of Hb-AuNCs comes from the ligand-metal charge transfer between surface ligands of Hb and the gold cores with high oxidation states. The biocompatibility assays including cell viability and fluorescence imaging, demonstrated high biocompatibility of Hb-AuNCs. For the qualitative analysis, three Hp phenotypes in plasma, Hp 1-1, Hp 2-1, and Hp 2-2, were successfully discriminated according to changes in the fluorescence intensity and peak position of the maximum intensity of Hb-AuNCs. Our work provides a practical method with facile and rapid properties for the qualitative analysis of three Hp phenotypes in human blood plasma.

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