Design of AgNPs doped chitosan/sodium lignin sulfonate/polypyrrole films with antibacterial and endotoxin adsorption functions

There is an urgent need to develop materials to prevent bacterial infection and the deleterious effects of endotoxins. In this study, we introduce a one-step electrodeposition method to prepare films composed of chitosan/Ag/polypyrrole and layer-by-layer self-assembly to introduce lignin sulphonate (LS) to obtain chitosan/Ag/polypyrrole/LS films. Antibacterial effects against both E. coli and S. aureus are shown by bacterial growth profiles and observation of bacteriostatic zones. Meanwhile, the addition of self-assembled LS improved the antibacterial effect of the film. For E. coli, the inhibition zone diameter was 0.93 cm, while for S. aureus, the inhibition zone diameter was 0.72 cm. Rapid and efficient endotoxin adsorption effects were shown whereby the electrostatic interactions between chitosan and endotoxin molecules played a major role. After adsorption for 1 h, in initial concentration of 1 EU/mL endotoxin solution, the adsorption efficiency could reach up to 85 %, while in initial concentration of 5 EU/mL endotoxin solution, the adsorption efficiency could reach up to 87.6 %. The results suggest chitosan/Ag/polypyrrole/LS films for their capability as a new type of antibacterial film with intrinsic endotoxin adsorption activity.

Effect of oXiris-CVVH on the Clinical Outcomes of Patients with Septic Shock: An Inverse Probability of Treatment-Weighted Analysis

BACKGROUND

Limited previous studies had proved that oXiris-continuous veno-venous hemofiltration (CVVH) could decrease endotoxins and inflammatory factors, thereby improving circulation's stability. However, conclusive data are lacking regarding the comparison between oXiris membrane (with the function of removing endotoxins and decreasing inflammatory factors) and AN69 filters (with the only function of decreasing inflammatory) on the mortality of patients with septic shock. The potential mechanisms of oXiris that might influence the mortality of septic shock patients remain unexplored.

METHODS

This is a single-center, retrospective cohort study. The experimental group (30 patients with septic shock) was treated with oXiris-CVVH, and the control group (46 patients with septic shock) was treated with AN69 filter-CVVH. We employed the inverse probability of treatment-weighting method (IPTW), doubly robust estimation, and mediating effect analysis to analyze those clinical outcomes, with a special focus on the results of 28-day mortality, 72-h lactate, the need for norepinephrine (NE) in the next 72 h.

RESULTS

A total of 76 patients with septic shock who received blood purification therapies were enrolled. After IPTW, differences in patient characteristics have been minimized. The 28-day mortality in the control group is higher than in the treatment group (73.3% vs. 47.3%, p < 0.001; median survival time: 10 vs. ≥28 days, log-rank p = 0.0366). And the 25% decrease and the 50% decrease in demand for NE in the next 72 h are different between the treatment and control groups (median time of 25% decrease in demand: 24 vs. >72 h, log-rank p = 0.0126; median time of 50% decrease in demand: 24 vs. >72 h, log-rank p = 0.0322). The 72-h lactic acid level and white blood cell (WBC) counts in the oXiris group are lower than in the control group. The 72-h lactate fully mediated the effects of oXiris on 28-day mortality after confounds adjustment.

CONCLUSIONS

For septic shock patients, the use of oXiris-CVVH was associated with lower mortality and appeared to reduce lactate, NE dosage, PCT, and WBC counts, as compared to AN69-CVVH.

Covalently immobilized chemically modified lysozyme as a sorbent for bacterial endotoxins (lipopolysaccharides)

Chemical modification of lysozyme was carried out using benzaldehyde and anisaldehyde. It was shown that chemical modification affects only 1-2 amino groups of the protein molecule which does not prevent further covalent immobilization of lysozyme using the remaining free amino groups. The bacteriolytic activity of lysozyme is preserved after chemical modification and after subsequent covalent immobilization. As a result of chemical modification immobilized lysozyme more effectively adsorbs bacterial lipopolysaccharides (endotoxins). Adsorption of immunoglobulin G does not increase after modification. The sorbents obtained in this work can be used for the future development of new medical material for the extracorporeal treatment of sepsis. The proposed scheme for the modification and immobilization of lysozyme can be used with various aldehydes for the preparation of sorbents with different properties.

In Vitro Study of Endotoxin Adsorption by a Polymyxin B-Immobilized Fiber Column

BACKGROUND

Polymyxin B-immobilized fiber (PMX-F) columns are used as therapeutic interventions for septic shock. The clinical efficacy has been reported for 2-h applications, but their ability to adsorb endotoxin over longer treatments has not been fully elucidated. We hypothesized that PMX-F columns are capable of endotoxin removal for more than 2 h.

METHOD

We designed closed circuits incorporating either a PMX-F column with an 8.5-mL priming volume (PMX-01R) or a sham-control column, and used inactivated fetal bovine serum as the circulating perfusate. Endotoxin was continuously injected at a fixed rate for 24 h, and perfusate endotoxin concentrations were measured at fixed time points. PMX-01R endotoxin adsorption was calculated from the difference in the endotoxin concentrations.

RESULTS

PMX-01R endotoxin adsorption increased continuously in a virtually linear manner.

CONCLUSIONS

The PMX-01R column showed sustained endotoxin adsorption for at least 24 h. This indicated that PMX-F columns would be capable of clinical endotoxin removal for 24 h.