Silver materials have been widely used as antimicrobial agents. Notably, silver nanoparticles have emerged as a new generation of nanoproducts for biomedical and environmental applications in recent years. However, ultrasmall silver nanoclusters (NCs) (∼2 nm) have rarely been used to kill bacteria and their antibacterial mechanisms have not yet been fully elucidated. Herein, we studied the antibacterial activities of bifunctional fluorescent DHLA-AgNCs against three types of bacteria. The results showed that DHLA-AgNCs exhibited excellent antibacterial activities against Gram-negative E. coli, which could efficiently inhibit the growth of E. coli DH 5α and E. coli DSM 4230 cells at a concentration of 15 and 10 μg mL, respectively. Meanwhile AgNCs demonstrated no apparent antibacterial activity against Gram-positive S. aureus. Then, the antibacterial mechanisms of AgNCs were systematically investigated. We found that AgNCs affected the growth of different E. coli strains in different ways. AgNCs inhibited the growth of E. coli DH 5α mainly through damaging the outer cellular membrane and permeating into the cells, followed by the antibacterial effect of the internalized AgNCs and released silver ions. AgNCs, however, inhibited the growth of E. coli DSM 4230 cells mainly through diffusing into E. coli DSM 4230 cells and damaging their respiratory chain. These results clearly indicated that different bacterial strains (e.g. different E. coli strains) should be taken into consideration in future studies. Our work facilitates further investigation of the design of new antibacterial silver nanomaterials with different sizes.

BackgroundAcute exacerbation of chronic obstructive pulmonary disease (AECOPD) aggravates the overall severity in COPD patients, resulting in severe morbidity and mortality. However, there are no objective biomarkers currently available to predict the development of AECOPD. Several studies have indicated that galectin-3 (Gal-3) is involved in diseases characterized by excessive inflammatory response and fibrosis. The objective of this study was to examine the dynamic changes of Gal-3 in acute exacerbation and convalescence phases of COPD.Material/MethodsSerum levels of Gal-3, high sensitivity C-reactive protein (hsCRP), and prohormone of brain natriuretic peptide (pro-BNP) were determined using multiplex enzyme-linked immunosorbent assay kits. Serum levels of Gal-3 in 44 patients with COPD were further analyzed and correlated with the parameters of lung function and the biomarkers of systemic inflammation.ResultsThe mean level of serum Gal-3 was significantly higher in acute exacerbation of COPD compared with the level in COPD convalescence phase (32.10±9.83 versus 29.02±8.68 ng/mL, p<0.01). Serum levels of Gal-3 positively correlated with hsCRP (r=0.354, p=0.018 for total patients) and pro-BNP (r=0.319, p=0.035 for total patients) in AECOPD. In addition, the level of Gal-3 was the highest in the current smoker group, and the lowest in the never-smoker group in either the acute exacerbation phase (33.91±3.55 versus 29.12±11.73 ng/mL, p=0.036) or the convalescence phase (30.94±3.40 versus 27.76±9.68 ng/mL, p=0.045) of COPD.ConclusionsOur results indicated that serum Gal-3 is increased in AECOPD patients, which is also positively associated with systemic inflammation and smoking in patients with COPD, suggesting that Gal-3 might be a valuable biomarker for AECOPD.

No abstract

No abstract

To further evaluate the potential renal targeting profile of low molecular weight hydroxyethyl chitosan (LMWHC) we developed before, prednisolone (Pre) was conjugated with LMWHC by EDC/NHS chemistry to improve the therapeutic effect of glucocorticoids in vivo. The conjugate was denoted as LMWHC-Pre. The prednisolone content of the conjugate was determined by reversed-phase high-performance liquid chromatography (HPLC) with Kromasil C18 column. The results showed that the average coupling degree of prednisolone to LMWHC was 76.7±3.2 μg·mg-1. The stability and physicochemical characterization of LMWHC-Pre under various conditions were also investigated. To study the fate of LMWHC-Pre after intravenous (i.v.) administration, fluorescein isothiocyanate (FITC) was coupled to the conjugate to explore the renal targeting efficacy. The in vivo results showed that significant amount of the conjugate was accumulated into the kidneys while negligible signal could be detected when the mixture of FITC-LMWHC and prednisolone was co-administered. The preliminary pharmacodynamics study of LMWHC-Pre showed that the conjugate could effectively alleviate the nephrotic syndrome of rats induced by minimal change nephrosis (MCN) model. Toxicity study also revealed that there was little glucocorticoid-induced osteoporosis by LMWHC-Pre upon 20 days of treatment. From this study, LMWHC-Pre may be employed as an effective potential drug candidate for the treatment of chronic renal disease.