ABSTRACT
Tuberculosis, a fatal infectious disease caused by Mycobacterium tuberculosis (M.tb), is difficult to treat with antibiotics due to drug resistance and short drug half-life. Phototherapy represents a promising alternative to antibiotics in combating M.tb. Exploring an intelligent material allowing effective tuberculosis treatment is definitely appealing, yet a significantly challenging task. Herein, an all-in-one biomimetic therapeutic nanoparticle featured by aggregation-induced second near-infrared emission, granuloma-targeting, and self-oxygenation is constructed, which can serve for prominent fluorescence imaging-navigated combined phototherapy toward tuberculosis. After camouflaging the biomimetic erythrocyte membrane, the nanoparticles show significantly prolonged blood circulation and increased selective accumulation in tuberculosis granuloma. Upon laser irradiation, the loading photosensitizer of aggregation-induced emission photosensitizer elevates the production of reactive oxygen species (ROS), causing M.tb damage and death. The delivery of oxygen to relieve the hypoxic granuloma microenvironment supports ROS generation during photodynamic therapy. Meanwhile, the photothermal agent, Prussian blue nanoparticles, plays the role of good photothermal killing effect on M.tb. Moreover, the growth and proliferation of granuloma and M.tb colonies are effectively inhibited in the nanoparticle-treated tuberculous granuloma model mice, suggesting the combined therapeutic effects of enhancing photodynamic therapy and photothermal therapy.
ABSTRACT
The total viable count (TVC) of bacteria is an important index to evaluate the freshness and safety of dishes. To improve the accuracy and robustness of spectroscopic detection of total viable bacteria count in a complex system, a new method based on a near-infrared (NIR) hyperspectral hybrid model and Support Vector Machine (SVM) algorithms was developed to directly determine the total viable count in intact beef dish samples in this study. Diffuse reflectance data of intact and crushed samples were tested by NIR hyperspectral and processed using Multiplicative Scattering Correction (MSC) and Competitive Adaptive Reweighted Sampling (CARS). Kennard-Stone (KS) and Samples Set Partitioning Based on Joint X-Y Distance (SPXY) algorithms were used to select the optimal number of standard samples transferred by the model combined with root mean square error. The crushed samples were transferred into the complete samples prediction model through the Direct Standardization (DS) algorithm. The spectral hybrid model of crushed samples and full samples was established. The results showed that the Determination Coefficient of Calibration (RP2) value of the total samples prediction set increased from 0.5088 to 0.8068, and the value of the Root Mean Square Error of Prediction (RMSEP) decreased from 0.2454 to 0.1691 log10 CFU/g. After establishing the hybrid model, the RMSEP value decreased by 9.23% more than before, and the values of Relative Percent Deviation (RPD) and Reaction Error Relation (RER) increased by 12.12% and 10.09, respectively. The results of this study showed that TVC instewed beef samples can be non-destructively determined based on the DS model transfer method combined with the hybrid model strategy. This study provided a reference for solving the problem of poor accuracy and reliability of prediction models in heterogeneous samples.