Alkaline phosphatase-activated prodrug system based on a bifunctional CuO NP tandem nanoenzyme for on-demand bacterial inactivation and wound disinfection.

Nanozymes are promising antimicrobials, as they produce reactive oxygen species (ROS). However, the intrinsic lack of selectivity of ROS in distinguishing normal flora from pathogenic bacteria deprives nanozymes of the necessary selectivities of ideal antimicrobials. Herein, we exploit the physiological conditions of bacteria (high alkaline phosphatase (ALP) expression) using a novel CuO nanoparticle (NP) nanoenzyme system to initiate an ALP-activated ROS prodrug system for use in the on-demand precision killing of bacteria. The prodrug strategy involves using 2-phospho-L-ascorbic acid trisodium salt (AAP) that catalyzes the ALP in pathogenic bacteria to generate ascorbic acid (AA), which is converted by the CuO NPs, with intrinsic ascorbate oxidase- and peroxidase-like activities, to produce ROS. Notably, the prodrug system selectively kills Escherichia coli (pathogenic bacteria), with minimal influence on Staphylococcus hominis (non-pathogenic bacteria) due to their different levels of ALP expression. Compared to the CuO NPs/AA system, which generally depletes ROS during storage, CuO NPs/AAP exhibits a significantly higher stability without affecting its antibacterial activity. Furthermore, a rat model is used to indicate the applicability of the CuO NPs/AAP fibrin gel in wound disinfection in vivo with negligible side effects. This study reveals the therapeutic precision of this bifunctional tandem nanozyme platform against pathogenic bacteria in ALP-activated conditions.

6-Aza-2-Thiothymine-Capped Gold Nanoclusters as Robust Antimicrobial Nanoagents for Eradicating Multidrug-Resistant Escherichia coli Infection.

Multidrug-resistant bacterial infections, especially those caused by multidrug-resistant Escherichia coli (E. coli) bacteria, are an ever-growing threat because of the shrinking arsenal of efficacious antibiotics. Therefore, it is urgently needed to develop a kind of novel, long-term antibacterial agent effectively overcome resistant bacteria. Herein, we present a novel designed antibacterial agent-6-Aza-2-thiothymine-capped gold nanoclusters (ATT-AuNCs), which show excellent antibacterial activity against multidrug-resistant E. coli bacteria. The prepared AuNCs could permeabilize into the bacterial cell membrane via binding with a bivalent cation (e.g., Ca2+), followed by the generation of reactive oxygen species (e.g., •OH and •O2-), ultimately resulting in protein leakage from compromised cell membranes, inducing DNA damage and upregulating pro-oxidative genes intracellular. The AuNCs also speed up the wound healing process without noticeable hemolytic activity or cytotoxicity to erythrocytes and mammalian tissue. Altogether, the results indicate the great promise of ATT-AuNCs for treating multidrug-resistant E. coli bacterial infection.

[Protective effect of vitrification and controlled slow freezing on immature testicular tissue].

OBJECTIVE: To explore and compare the current mainstream testicular tissue freezing methods, namely vitrification and controlled slow freezing, and optimize the best testicular tissue freezing methods. METHODS: Testicular tissues of 3-week-old mice and <2-year old prepubertal cynomophage monkeys were collected and cut to 6-26 mm3, and divided into three groups: Fresh group, vitrification group and controlled slow freezing group were resuscitated after 5-7 days of freezing. HE staining, immunofluorescence staining, TUNEL staining and Western blot were used to evaluate the frozen-thawed testicular tissue. RESULTS: 1. In the testes of C57BL6/J mice, the expression level of spermatogonial stem cell marker UCHL1 in the controlled slow freezing group was higher than that in the vitrification group, and the content of apoptotic cells (TUNEL+ cells) was lower than that in the vitrification group. 2. In the testicular tissue of cynomolgus monkeys, the expression levels of spermatogonial stem cell markers UCHL1 and cell proliferation marker PCNA in the CSF group were higher than those in the vitrification group. CONCLUSION: Both vitrification and CSF can successfully preserve the testes of immature mice and cynomolgus monkeys before puberty. However, in the vitrification, there are more frozen damaged areas in the testicular tissue with the frozen volume of 6-26mm3, which may affect the cryopreservation of spermatogonial stem cells in the testicular tissue.

[Expressions of FOXO1/3a/4/6 in human testis and their roles in testicular aging].

OBJECTIVE: To investigate the expression rules of FOXO1a, FOXO3a, FOXO4 and FOXO6 proteins in the human testis, and explore their roles in the development and progression of testicular aging. METHODS: We collected the para-carcinoma testis tissue from 4 testis cancer patients aged 28, 31, 32 and 46 years, and the testis tissue from another 2 PCa patients aged 66 and 81 years after castration surgery from January 2018 to December 2020. We detected the expressions of FOXO1a, FOXO3a, FOXO4 and FOXO6 proteins in the testis tissue by Western blot, determined the locations of FOXO1a, FOXO3a, FOXO4 and FOXO6 in the testis cells by immunofluorescence staining, and performed semi-quantitative and statistical analyses using image J and SPSS 23.0 software, respectively. RESULTS: The expression levels of FOXO1a and FOXO3a proteins were significantly decreased in the testis tissue of the elderly patients (P < 0.01), with an age-dependent reduction in the proportion of the positive cells. No statistically significant difference was observed in the expression levels of FOXO4 and FOXO6 between different age groups. FOXO1a was mainly expressed at the base of the seminiferous tubules, FOXO3a and FOXO4 in the Leydig cells, and FOXO6 in the seminiferous tubules. In addition, FOXO4 underwent age-related nuclear translocation in the senescent Leydig cells, suggesting its involvement in the aging of Leydig cells. CONCLUSION: FOXO1a/3a/4 may be closely related to human testicular aging and corresponding pathological changes, but its underlying mechanism remains to be further explored.

Sikokianin D, a new C-3/C-3"-biflavanone from the roots of Wikstroemia indica.

A new 3,3''-biflavanone, sikokianin D (1), was isolated from the roots of Wikstroemia indica, together with two known compounds. Their structures were elucidated by chemical evidence and spectral analyses, including HR-ESI-MS, and 1D- and 2D-NMR techniques.

5-Bromo-N-(3,4-dimeth-oxy-benz-yl)pyridin-2-amine.

The title compound, C(14)H(15)BrN(2)O(2), an inter-mediate in drug discovery, was synthesized by the reaction of 5-bromo-pyridin-2-amine and 3,4-dimeth-oxy-benzaldehyde. In the crystal, molecules are linked via pairs ofN-H⋯N hydrogen bonds, leading to the formation of inversion dimers. A short contact occurs between the aryl H atom (ortho position from N) and the centroid of the benzene ring.