Rosin modified aminated mesoporous silica adsorbed tea tree oil sustained-release system for improve synergistic antibacterial and long-term antibacterial effects.

Tea tree oil, a natural antibacterial compound, cannot be used effectively because of its volatile nature. In this work, a biocompatible carrier was prepared and loaded with tea tree essential oil. The carrier was prepared via the electrostatic or chemical action of aminated mesoporous silica and sodium rosin for achieving a low volatilization rate of tea tree essential oil. A synergistic antibacterial effect was observed between sodium rosin and tea tree essential oil. This method utilized the positive charge of the amino group and the condensation reaction with the carboxyl group to achieve physical and chemical interactions with sodium rosin. Fourier Transform Infrared, Brunauer-Emmet-Teller, Zeta potential, SEM, TEM, and TG were performed to characterize the structure and properties of the samples. Compared to the electrostatic effect, the chemically modified system exhibited a longer sustained release, and the sustained release curve followed the Korsmeyer-Peppas release model. Also, the antibacterial properties of the chemically modified system exhibited better minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) respectively, the MIC and MBC forE. coliwere 0.3 mg ml-1and 0.6 mg ml-1respectively, forS. aureuswere 0.15 mg ml-1and 0.3 mg ml-1respectively. More strikingly, the sample also demonstrated long-term antibacterial performance. Therefore, this work provides a new way for the delivery of volatile antibacterial drugs to achieve sustained-release and long-lasting antibacterial effects.

Long-lasting anti-bacterial activity and bacteriostatic mechanism of tea tree oil adsorbed on the amino-functionalized mesoporous silica-coated by PAA.

Tea tree oil (TTO) is an efficient natural antibacterial agent. However, the bacteriostatic effect of TTO does not prevail for a long period because of the volatile nature of the oil. Therefore, a novel sustained-release formulation of TTO should be developed for improving the applicability of TTO. Herein, the mesoporous silica was selected for constructing a carrier for TTO. Mesoporous silica is non-toxic, easy to modify and exhibited an adjustable pore size. First, the mesoporous silica was modified by an aminated silane coupling agent (NH2-MCM-41). Then, the polyacrylic acid (PAA) was bonded by electrostatic bonds (PAA-NH2-MCM-41), which imparted the sustained-release effect in the TTO, supported in the mesoporous silica channel (TTO/PAA-NH2-MCM-41). The prepared bacteriostatic agent can achieve long-term sustained-release properties. At room temperature (26 ℃), the release rate of TTO after 11 h release reached 50 %. However, the release rate of TTO from TTO/PAA-NH2-MCM-8 reached only 42 % after 24 h. Furthermore, the sustained release behavior of TTO/PAA-NH2-MCM-41 was consistent with the Korsmeyer-Peppas kinetic model. Compared to TTO, TTO/PAA-NH2-MCM-41 exhibited a stable and sustained bacteriostatic effect even after 50 days in a natural environment. The minimum inhibitory concentration (MIC) value of the TTO/PAA-NH2-MCM-41 against Escherichia coli (E. coli) was 0.37∼0.44 mg/mL. TTO altered the cell morphology of E. coli and broke the integrity of the cell membrane, leading to cell death.

[Effect of Xuebijing injection treatment on acute respiratory distress syndrome: a multicenter prospective randomized control clinical trial].

OBJECTIVE: To assess the therapeutic effect of Xuebijing injection on adult patients with acute respiratory distress syndrome (ARDS). METHODS: A multicenter prospective randomized control study was conducted at 10 intensive care units in Jiangsu province. A total of 172 early ARDS patients were randomly divided into Xuebijing treatment and control groups. All patients received routine therapy of ARDS while additional Xuebijing injection 100 ml was administered in the treatment group intravenously for 7 days. Lung injury score, acute physiology and chronic health evaluation II (APACHE II) score, multiple organ dysfunction score (MODS) and PaO2/FiO2 of the patients was recorded before and after treatment. Mortality at 28 days and the duration of mechanical ventilation were compared between two groups. RESULTS: Ninety-one patients were assigned to receive Xuebijing injection and 81 patients as control; Mortality at Days 28 and 90, the duration of mechanical ventilation and ventilation free days showed no difference between two groups (P > 0.05). PaO2/FiO2 improved after randomization versus pre-treatment in all patients. There was no significant difference between two groups. Murray scores were not significantly different between two groups. In a subgroup analysis of patients with pulmonary infection, pulmonary contusion and extra-pulmonary cause, two groups had no difference in mortality at Day 28, mortality at Day 90, the duration of mechanical ventilation, ventilation free days and days of ICU stay (P > 0.05). CONCLUSION: The treatment of Xuebijing injection early in course of ARDS does not improve the mortality of ARDS patients. But it may improve lung function and oxygenation. Further studies are warranted.