Rifaximin discontinuation during broad-spectrum antibiotic treatment in critically ill patients with hepatic encephalopathy

Hepatic encephalopathy(HE)is one of the main complications of cirrhosis,characterized by a wide spectrum of neuropsychiatric alterations that lead to an increase in mortality,morbidity and recurrent hospitalizations.Due to the central role in HE pathogenesis of ammonia and other neurotoxins primarily produced by the gut microbiota,the main therapeutic approaches for the treatment of HE are based on the modulation of the gut microbiota.Rifaximin is a non-absorbable broad-spectrum antibiotic,that is effective against ammonia-producing grampositive,gram-negative,and anaerobic species,approved for the treatment of HE in secondary prophylaxis.The chronic administration of rifaximin in this setting is associated with a lower risk of HE recurrence and mortality,while the role of rifaximin for the treatment of an overt-HE episode in inpatients is still unclear.Limited data exist about the coadministration of rifaximin and broad-spectrum antibiotics commonly used to treat concomitant infections,as patients receiving or recently treated with antibiotics were frequently excluded from clinical trials.In this editorial we comment on the article by Ward et al published in the recent issue of the World Journal of Hepatology.It is a single center,retrospective,quasiexperimental,pharmacist-driven protocol,with the aim to evaluate the feasibility and safety of rifaximin discontinuation in critically ill patients with HE and chronic liver disease receiving broad-spectrum antibiotic therapies in intensive care units.The study revealed no differences between the protocol and control group in terms of primary outcome(days alive and free of delirium and coma to day 14)and secondary outcomes which include:Intensive care mortality,intensive care length of stay,intravenous vasopressor requirement changes and adverse effects rate.Therefore,rifaximin discontinuation during broad-spectrum antibiotic therapy does not appear to negatively impact the clinical status of critically ill liver patients,with a similar safety profile and significant cost savings,as compared to the coadministration of rifaximin and broad-spectrum antibiotics.In agreement with Ward et al,a recently published double-blind,randomized controlled trial provided additional evidence to support the feasibility of withholding rifaximin during broad-spectrum antibiotic therapy in critically ill cirrhotic patients.However,given the limitations of these studies,further multicentric and prospective clinical trials,enrolling a larger sample of non-critically ill patients,are needed to better establish the role of rifaximin in this setting.

Can rifaximin for hepatic encephalopathy be discontinued during broad-spectrum antibiotic treatment?

Hepatic encephalopathy(HE)is a formidable complication in patients with decompensated cirrhosis,often necessitating the administration of rifaximin(RFX)for effective management.RFX,is a gut-restricted,poorly-absorbable oral rifamycin derived antibiotic that can be used in addition to lactulose for the secondary prophylaxis of HE.It has shown notable reductions in infection,hospital readmission,duration of hospital stay,and mortality.However,limited data exist about the concurrent use of RFX with broad-spectrum antibiotics,because the patients are typically excluded from studies assessing RFX efficacy in HE.A pharmacist-driven quasi-experimental pilot study was done to address this gap.They argue against the necessity of RFX in HE during broad-spectrum antibiotic treatment,particularly in critically ill patients in intensive care unit(ICU).The potential for safe RFX discontinuation without adverse effects is clearly illuminated and valuable insight into the optimization of therapeutic strategies is offered.The findings also indicate that RFX discontinuation during broadspectrum antibiotic therapy was not associated with higher rates of delirium or coma,and this result remained robust after adjustment in multivariate analysis.Furthermore,rates of other secondary clinical and safety outcomes,including ICU mortality and 48-hour changes in vasopressor requirements,were comparable.However,since the activity of RFX is mainly confined to the modulation of gut microbiota,its potential utility in patients undergoing extensive systemic antibiotic therapy is debatable,given the overlapping antibiotic activity.Further,this suggests that the action of RFX on HE is class-specific(related to its activity on gut microbiota),rather than drug-specific.A recent double-blind randomized controlled(ARiE)trial provided further evidence-based support for RFX withdrawal in critically ill cirrhotic ICU patients receiving broad-spectrum antibiotics.Both studies prompt further discussion about optimal therapeutic strategy for patients facing the dual challenge of HE and systemic infections.Despite these compelling results,both studies have limitations.A prospective,multi-center evaluation of a larger sample,with placebo control,and comprehensive neurologic evaluation of HE is warranted.It should include an exploration of longer-term outcome and the impact of this protocol in non-critically ill liver disease patients.

Improving treatment plan and mental health in children with abdominal infection for broad-spectrum bacterial infections

BACKGROUND Pediatric abdominal infection is a common but serious disease that requires timely and effective treatment.In surgical treatment,accurate diagnosis and rational application of antibiotics are the keys to improving treatment effects.AIM To investigate the effect of broad-spectrum bacterial detection on postoperative antibiotic therapy.METHODS A total of 100 children with abdominal infection who received surgical treatment in our hospital from September 2020 to July 2021 were grouped.The observation group collected blood samples upon admission and sent them for broad-spectrum bacterial infection nucleic acid testing,and collected pus or exudate during the operation for bacterial culture and drug sensitivity testing;the control group only sent bacterial culture and drug sensitivity testing during the operation.RESULTS White blood cell count,C-reactive protein,procalcitonin,3 days after surgery,showed better postoperative index than the control group(P<0.05).The hospital stay in the observation group was significantly shorter than that in the control group.The hospitalization cost in the observation group was significantly lower than that in the control group,and the difference between the two groups was statistically significant(P<0.05).CONCLUSION Early detection of broad-spectrum bacterial infection nucleic acids in pediatric abdominal infections can help identify pathogens sooner and guide the appropriate use of antibiotics,improving treatment outcomes and reducing medical costs to some extent.

The Acute Toxicity Test in Mice and Bacteriostasis in vitro of Yandureqing and Its Microemulsion

[Objective] The aim of this study is to evaluate the safety and bacteriostasis of Yandureqing(AEE)and its microemulsion(AEE-ME).[Method]The acute toxicity was tested in mice by intragastric administration,and median lethal dose(LD50)as well as its 95% confidence interval was calculated by modified Karber method;the bacteriostasis was investigated by cylinder plate method.[Result]LD50 of AEE in mice was 10.937 g/kg with the 95% confidence interval of 9.309-12.850 g/kg;and LD50 of AEE-ME in mice was 5.357 g/kg with the 95% confidence interval of 4.388-6.566 g/kg.The MICs of AEE to Escherichia coli O149 from swine,Staphylococcus aureus,Salmonella pullorum and Streptococcus agalactiae were 10.00,20.00,20.00 and 10.00 mg/ml,respectively;while the MICs of AEE-ME to the 4 kinds of bacteria mentioned above were 5.00,10.00,5.00 and 5.00 mg/ml in turn,and that to Pseudomonas aeruginosa is 20.00 mg/ml.[Conclusion]AEE is an actually nontoxic drug and AEE-ME belongs to the low toxic preparation.AEE and AEE-ME have obvious bacteriostasis,in which AEE-ME is superior to AEE.

Study on In vitro Bacteriostasis of the Different Extract from Ilex Kudingcha C.J.Tseng

[ Objective ] The aim was to study bacteriostatic activity of the different extract from Ilex Kudingcha C. J. Tseng. [ Method ] By using test tube 2 -fold dilution method and Kirby-Baueer Disc Diffusionto,we conducted inhibitory test on S. aureus and E, coil and determined the minimal inhibitory concentration （MIC） and minimum bactericidal concentration （MBC）and the diameter of inhibition zone. [ Result ] The extract 1 had fairly strong in vitro bacteriostasis activities and than the extract2 and extract3. The MIC and MBC was 3.91 mg/ml and 31.25 mg/ml on S. aureus and E. coil [ Conclusion] The result showed that the different extract from Ilex Kudingcha C. J. Tseng had varying amount of different bacteriostatic activities,the Ilex Kudingcha C. J. Tseng was developed new and safe bacteriostatic reagent to provide reference.

Research Progress on Bacteriostasis of Nano Selenium

Nano selenium which has the advantages of low toxicity,strong activity and high biocompatibility has broad-spectrum antibacterial activity to bacteria,fungi,viruses and parasites,and has a broad application prospect in the field of inhibiting microbial infection.This paper mainly reviews the progress in the types and mechanisms of selenium inhibition microorganisms,and prospects the development of the antibacterial activities of selenium nanoparticles.

Associated Bacteriostasis Research of Coptidis Rhizoma-Folium Isatidis and Coptidis Rhizoma-Flos Poprli against Escherichia coli O2

[Objective] The paper was to explore the combined inhibitory effect of rhizoma coptidis-folium isatidis and rhizoma coptidis-flos poprli against Escherichia coli O2.[Method] Contrast test of single and associated bacteriostasis against known serotype E. coli O2 was conducted using microcheckerboard method.[Result] The MIC of rhizoma coptidis, folium isatidis and flos poprli were 1/8 extracting liquid, 1/8 extracting liquid and 1/2 extracting liquid, respectively. When combined with folium isatidis or flos poprli, the MIC of rhizoma coptidis was 1/8 extracting liq-uid or 1/16 extracting liquid compared with single use. When combined with rhizoma coptidis, the MIC of folium isatidis and flos poprli were 1/8 extracting liquid and 1/16 extracting liquid.[Conclusion] When rhizoma coptidis was combined with folium isatidis or flos poprli, the FIC values were 2 and 0.625, performing independent action and additive effect, respectively.

传统发酵乳品中产广谱细菌素乳酸菌选育

为选育产广谱细菌素乳酸菌,采用琼脂扩散法对甘肃牧区传统发酵乳品中分离纯化的96株乳酸菌进行了筛选,并确定产细菌素菌株,具有最佳抑菌效果的菌株经重离子束12C6+辐照诱变,再采用培养皿分区法进行6种指示菌广谱抑菌性能比较。结果表明,琼脂扩散法筛选出抑菌效果最佳的产细菌素菌株Lp1,经辐照诱变得到98株突变菌,选育出对大肠埃希氏菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)、单核细胞增生李斯特氏菌(Listeria monocytogenes)、沙门氏菌(Salmonella)、志贺氏菌(Shigella)和克罗诺杆菌(Cronobacter)抑菌性能均明显优于出发菌株Lp1的5株突变株L088、L087、L063、L049、L010进行广谱抑菌试验,其中菌株L088和L063为广谱抑菌性能较好菌株,突变株L088对上述6种指示菌的抑菌扇环半径比出发菌株Lp1抑菌扇环半径分别提高47.81%、33.28%、22.97%、45.25%、21.39%、40.21%,突变株L063对上述6种指示菌的抑菌扇环半径比出发菌株Lp1抑菌扇环半径分别提高54.27%、29.18%、25.37%、58.03%、17.85%、42.13%。采用培养皿分区法可同时在1个培养皿中完成检测6种指示菌的抑菌试验,可高效筛选产广谱细菌素乳酸菌。

茶黄素体外抑菌作用研究

通过体外试验研究茶黄素对大肠埃希氏菌、金黄色葡萄球菌、枯草芽孢杆菌、肠球菌、禽肺炎克雷伯、鸭源鸡杆菌、禽肠炎沙门氏菌、野鸟黏质沙雷氏菌、禽巴氏杆菌的抑菌作用。采用最低抑菌浓度(MIC)和最小杀菌浓度(MBC)测定法研究茶黄素的抑菌作用及杀菌作用。结果显示,茶黄素对禽巴氏杆菌、鸭源鸡杆菌等具有抑菌作用,并与其浓度呈正相关,而对大肠埃希氏菌、禽肠炎沙门氏菌、黏质沙雷氏菌等无作用;茶黄素浓度为128μg/mL时,其对鸭源鸡杆菌生长具有抑制作用,当茶黄素浓度为512μg/mL时,其对禽巴氏杆菌C48-1生长具有抑制作用;当茶黄素浓度为512μg/mL时,其对禽巴氏杆菌和鸭源鸡杆菌具有杀菌作用。茶黄素在MBC浓度时能抑制生物被膜的形成能力。结果表明,茶黄素是一种天然抗菌剂,具有优良的替抗前景,促进绿色健康养殖。

发酵型茶醋的品质分析及抑菌性

以广西贺州生产的红茶(迎霜、月湾)、绿茶(开山白毛、茗山)为原料,分别与新鲜甘蔗汁混合发酵制备茶醋,考察其醋酸发酵过程中的色差、总酸、茶多酚、茶氨酸、总黄酮等指标变化,并通过电子鼻测定茶醋整体特征气味轮廓,同时采用牛津杯‐琼脂法分析4种茶醋对大肠埃希氏菌、金黄色葡萄球菌、白色念珠菌3种致病菌的抑菌效果。结果显示,绿茶(开山白毛、茗山)发酵体系的产酸能力较强,且茶多酚含量较高,茶醋中总黄酮成分保留较好;酸类、醇类、芳香化合物、烷类物质是茶醋的整体特征气味轮廓;以抑菌圈的大小判断4种茶醋的抑菌效果发现4种茶醋对大肠埃希氏菌、金黄色葡萄球菌、白色念珠菌都有一定的抑菌效果,抑菌圈明显,且茗山茶醋抑菌效果最佳,其对3种致病菌的抑菌作用为高敏感。不同茶叶品种发酵的茶醋品质和抑菌效果都有明显差别,但绿茶发酵的茶醋的口感比红茶发酵的茶醋丰富,且茶香、醋香味较为明显。

枯草芽孢杆菌LM 4-2发酵人参芦头生物转化人参皂苷Rd的研究

人参为我国传统的食药同源资源,但由于潜在的催吐等副作用,在人参炮制过程中需要做去芦处理,导致大量的人参芦头被丢弃,造成了严重的资源浪费,如何减少浪费、提高人参的综合应用需要进行相应研究。该研究建立了基于超高液相色谱法的人参皂苷检测方法,通过对13种人参皂苷单体进行测试,验证了该检测方法的准确性与可靠性。采用生物转化的方法,从6株候选菌株中筛选出转化人参皂苷Rd产量最高的菌株Bacillus subtilisLM 4-2,推测人参皂苷Rd经由Rc水解途径转化而来,进一步通过单因素试验与响应面试验设计,确定了菌株LM 4-2的最佳发酵条件为发酵时间20 d,温度30℃,料液比1∶4.3(g∶mL),接种量7.5%,该优化条件下Rd产量为(6.375±0.006)mg/g。同时,研究还对人参芦头发酵提取物的抗氧化性和抑菌效果进行了测定,抗氧化性试验发现DPPH自由基的清除率随着提取物浓度的增加而增加,提取物质量浓度为50 mg/mL时,DPPH自由基的清除率为82.55%;抑菌试验结果表明,在提取物质量浓度达到1.0 mg/mL时,对测试菌株金黄色葡萄球菌,枯草芽孢杆菌和大肠杆菌均能产生抑制作用,发酵液对3种测试菌株的最低抑制浓度分别为1.0、0.75和1.0 mg/mL。这些研究为通过菌株LM 4-2发酵人参芦头转化人参皂苷Rd、提高人参芦头的应用价值提供了参考。

添加牛粪堆肥对盆栽菊花生长及抑菌效果的影响

以3个菊花品种(‘辉煌’‘波尔多红’‘黄芙蓉’)为试材,采用添加不同比例(栽培基质与牛粪堆肥的体积比分别为1∶1、3∶1、5∶1)的牛粪堆肥进行基质复配的方法开展育苗试验,研究添加不同体积牛粪堆肥对栽培基质的理化性质以及盆栽菊花的形态、生理指标以及抑菌效果的影响,以期降低盆栽菊花染病机率,提高其观赏性。结果表明:随牛粪堆肥占比增加,基质容重增加,碱解氮、有效磷和速效钾含量增加,pH上升,孔隙度降低,EC值变化不明显。基质中添加牛粪堆肥可以显著促进盆栽菊花株高的伸长、花茎增粗、冠幅增大、叶片生长。3种盆栽菊花在对照中病情指数最高,可溶性蛋白质含量最低。处理盆栽菊花的成活率均为100%。在Y1处理下‘辉煌’长势最好,‘波尔多红’和‘黄芙蓉’在Y3处理时长势最好。‘辉煌’在Y1、Y2处理中病情指数最低,‘波尔多红’和‘黄芙蓉’在Y3处理中病情指数最低,因此在基质中适量添加牛粪堆肥能够促进盆栽菊花生长,降低其患病机率。

3种中草药水提物及其复配剂的体外抑菌效果研究

为了研究黄芪、甘草和苦豆子3种草药提取物及其复配剂的抑菌效果,试验采用水提法分别制备单剂中草药的提取液,按照L9(3^(4))正交试验设计得到9种不同复配剂,以大肠杆菌、金黄色葡萄球菌和沙门氏菌作为供试菌进行体外抑菌试验。结果显示,黄芪、甘草和苦豆子单剂对大肠杆菌、金黄色葡萄球菌和沙门氏菌均具有一定的抑菌效果,3种不同单剂提取物中,黄芪提取物对3种菌的抑菌效果最优,甘草、苦豆子次之。与单剂相比,3种中草药复配剂整体的抑菌效果均有提升,对大肠杆菌、金黄色葡萄球菌和沙门氏菌抑菌效果的最佳配比分别为1∶1∶2、2∶2∶1和4∶1∶2。经验证,3种中草药复配剂配比为1∶1∶2时,综合抑菌效果最佳,该复配剂作用大肠杆菌、金黄色葡萄球菌和沙门氏菌的抑菌圈直径分别为15.20、14.10、12.92mm。研究表明,在畜牧生产中,建议黄芪、甘草和苦豆子水提液的复配添加比为1∶1∶2,浓度为0.6、0.6、1.2 g/mL,从而最大限度地发挥中草药的抑菌作用。

抑菌性芽孢杆菌的筛选及特性研究

试验旨在从自然环境中筛选出具有抑菌效果的有益菌株,对其生长特性进行初步研究。试验以大肠杆菌为指示菌对12株芽孢杆菌进行初筛,筛选出6株具有抑菌活性的芽孢杆菌并对其进行鉴定。再以大肠杆菌和金黄色葡萄球菌做指示菌,对芽孢杆菌抗菌肽提取物进行抑菌性筛选,并对筛选出的菌株进行溶血性比较、药物敏感性测定及生长特性研究。结果显示,从实验室分离筛选出具有较强抑菌活性的菌株为芽孢杆菌G02和J12,经鉴定为暹罗芽孢杆菌(Bacillus siamensis);筛选出两株芽孢杆菌的提取物均具有分泌表面活性的能力,且分泌表面活性的能力相当;两株芽孢杆菌对16种药物的敏感性均在中敏以上;两菌株在6 h进入生长对数期,pH值维持在5~8之间,抑菌性在22 h达到高峰。研究表明,芽孢杆菌具有产生多种活性肽的能力,对常见病原菌具有一定的抑制作用,是一种潜在的传统抗生素替代品。

基于网络药理学探讨新疆桑白皮防龋机制及其对主要致龋菌作用的研究

目的探讨新疆桑白皮防龋潜在机制,并分析其对主要致龋菌的作用。方法TCMSP数据库筛选新疆桑白皮活性成分及靶点。Genecards、DisGENET和TTD数据库获取龋病靶点。获取新疆桑白皮防龋的共同靶点,并筛选核心基因。使用DAVID数据平台进行富集分析。采用AutoDock软件进行分子对接验证。通过体外抑菌实验,首先测定新疆桑白皮提取物对变异链球菌、血链球菌、黏性放线菌的50%最低抑菌浓度(50%minimum inhibitory concentration,MIC50)、最低杀菌浓度(minimal bactericidal concentration,MBC),并绘制生长曲线;分别测定新疆桑白皮提取物对变异链球菌、血链球菌、黏性放线菌浮游状态产酸、产糖和黏附能力的影响;通过结晶紫染色法测定新疆桑白皮提取物对主要致龋细菌单菌种50%最低生物膜抑制浓度(50%minimum biofilm inhibition concentration,MBIC50)和50%最低已形成生物膜清除浓度(50%minimum biofilm re-duction concentration,MBRC50),并利用扫描电子显微镜观察生物膜形态。结果筛选出新疆桑白皮防龋关键活性成分包括槲皮素、山奈酚、β-谷甾醇等。肿瘤坏死因子(tumor necrosis factor,TNF)、白细胞介素-6(interleu-kin-6,IL-6)、白细胞介素-1β(interleukin-1beta,IL-1β)等可能是新疆桑白皮防龋的关键靶点。富集分析结果显示新疆桑白皮可能对AGE-RAGE信号通路、IL-17信号通路、TNF信号通路等产生影响。抑菌实验结果显示新疆桑白皮提取物对变异链球菌、血链球菌、黏性放线菌的MIC50分别为0.5、0.5、0.25 mg/mL,MBC分别为4.0、2.0、1.0 mg/mL。新疆桑白皮提取物对3种主要致龋细菌浮游状态产酸、产多糖以及黏附能力的抑制作用较对照组强,差异均具有统计学意义(P<0.05)。新疆桑白皮提取物对变异链球菌、血链球菌、黏性放线菌的MBIC50分别为1.0、1.0、0.5 mg/mL,MBRC50分别为4.0、4.0、2.0 mg/mL。扫描电镜结果显示随着新疆桑白皮药物浓度的增加,生物膜形成量与对照组相比逐渐减少。结论新疆桑白皮可通过槲皮素、山奈酚、β-谷甾醇等活性成分,TNF、IL-6、IL-1β等关键靶点及多种作用途径防龋,不仅能抑制主要致龋细菌浮游状态生长、产酸、产糖、黏附能力且对致龋菌生物膜形成有一定的抑制作用。

枯草芽孢杆菌源抗菌肽发酵条件优化及其对雏鸡的抗炎作用

研究旨在优化枯草芽孢杆菌源抗菌肽发酵条件并探究其对雏鸡的抗炎作用。试验采用单因素方法筛选出适合枯草芽孢杆菌K4发酵的最佳氮源、碳源及初始pH值、温度、接种量。用筛选出的最佳发酵培养基和条件在50 L发酵罐内发酵1株能产抗菌肽的枯草芽孢杆菌K4,并将最终发酵液添加20%水溶性淀粉进行喷雾干燥。喷干后的菌粉使用大肠杆菌O2作为指示菌进行体外抑菌试验和雏鸡抗炎试验。结果显示,试验筛选出的最佳氮源为蛋白胨,最佳碳源为葡萄糖,培养基初始pH值为7.0,发酵温度为37℃,接种量为5%。喷干后的菌粉活菌数为4.60×10^(10)CFU/g。体外抑菌试验结果显示喷干菌粉对O2的抑菌圈为30 mm。雏鸡抗炎试验结果显示,大肠杆菌感染后的雏鸡灌服抗菌肽K4后的存活率为65%,比药物对照组高18.18%,说明枯草芽孢杆菌K4具有抑制大肠杆菌、降低雏鸡感染大肠杆菌后的死亡率的作用。

儿童化妆品检查及控制菌检查方法适用性研究

目的 考察市售儿童化妆品的卫生质量状况,研究其控制菌检查方法的适用性。方法 按照《化妆品安全技术规范》(2015年版)对市售常见的83批儿童化妆品进行微生物检查,通过参考《中国药典》(2020年版)控制菌检查方法对儿童化妆品的控制菌进行方法适用性试验,同时按不同剂型对其进行分类,并统计各剂型中防腐剂使用情况和占比问题,根据抑菌性样品添加的防腐剂成分类型统计防腐剂添加情况。结果 83批儿童化妆品经微生物检查合格率达100%;控制菌检查方法适用性试验表明,12批样品有不同程度的抑菌性,抑菌率为14.5%。样品需通过培养基稀释法或薄膜过滤法结合添加中和剂等方法消除抑菌性,其方法适用性试验才能通过,表明一些儿童化妆品自身的抑菌性较强。防腐剂统计结果可见,儿童化妆品中防腐剂苯氧乙醇的使用率最高,其次是苯甲酸钠和羟苯甲酯,且不同剂型的儿童化妆品对防腐剂添加的种类有相对的偏向选择适用性;抑菌性成分统计情况可见,氯苯甘醚和苯甲酸的抑菌性较强。结论 儿童化妆品在控制菌检查前建议进行方法适用性试验,在儿童防腐剂种类的选择上尽量选择安全有效且抑菌性较弱的防腐剂;本研究可为儿童化妆品生产企业提供参考。

壬醛与香芹酚复合抑菌微胶囊的制备及其对蓝莓的保鲜作用

为开发适合蓝莓采后贮藏保鲜的非接触式抑菌型天然固体缓释保鲜剂,以蓝莓采后主要病害病原菌灰霉菌为目标菌种,首先采用棋盘法从10种抑菌精油中筛选出具有协同抑菌作用的精油组合,再以包埋率为指标,通过响应面实验优化复合精油-β-环糊精微胶囊最佳制备工艺条件,并对其结构及功能特性进行表征,最后研究了微胶囊对蓝莓的保鲜效果。结果表明,壬醛与香芹酚具有协同抑制灰霉菌生长的效果;最佳制备工艺为β-环糊精/复合精油比8.75∶1(g/mL),包埋温度50.3℃,包埋时间2.0 h,微胶囊包埋率可达78.23%;扫描电镜观察微胶囊形态为规则晶体结构,平均粒径为16.86μm;抑菌实验表明,随着微胶囊用量增加,其对灰霉菌的抑制作用也提高;经过26 d释放后,在4℃和20℃微胶囊中复合精油最大累积释放率分别为50.52%和57.78%,具备缓释特性。在蓝莓保鲜实验中,贮藏至2周+8 d,相较空白对照(CK),6%(以果实质量分数计)微胶囊组蓝莓的商品率提高了39.73%、霉菌总数降低了61.39%,延缓了硬度、可溶性固形物、可滴定酸与抗坏血酸含量的下降,有效保持了蓝莓的品质。

己烯醛纳米乳工艺优化及其对壳聚糖薄膜的影响

为解决己烯醛在应用方面水不溶性、性质不稳定等问题,以吐温-80、黄原胶共同稳定乳液,采用高速剪切-超声破碎法制备己烯醛纳米乳。以粒径、多分散指数为指标,通过单因素、正交试验优化了制备纳米乳的工艺参数,并对其进行表征。当吐温-80、黄原胶质量分数分别为2%、0.3%,己烯醛体积分数8%,超声8 min时,该纳米乳的粒径、多分散指数最小,稳定性最强。纳米乳在处理温度-20~50℃,pH值2~10,离子浓度100~500 mmol/L的条件下均表现出良好稳定性。此外,纳米乳抑菌性能增强,表明乳化体系可提高己烯醛利用率。最后将乳液与壳聚糖复合制备复合膜,改善了壳聚糖膜的阻水、抑菌性能,拓宽了壳聚糖膜和己烯醛的应用范围。

钛合金表面主-被动抑菌改性方法研究进展

钛合金材料具有良好的耐腐蚀性、抗疲劳性和生物相容性,被广泛用于医疗领域,特别是可植入器械。医疗器械的型号多样、结构复杂、局部尺寸较小,且在使用过程中会接触多种媒介,极易黏附污渍,导致微生物的聚集,引发器械感染,安全、可靠的医疗器械是提高救治效率的关键。从细菌生长机制出发,将现有金属材料表面抑菌改性方法归纳为两大类:依靠抗菌涂层主动杀菌的改性方式和控制表面润湿性的被动抑制细菌黏附的改性方式。采用主动改性方式,虽然能从根本上杀死细菌,但是在实际应用中这些杀菌剂存在耐药性、成本高、生物毒性等问题。被动改性方式无法直接杀死细菌,一旦表面被细菌定植,就会失去抑菌效果。为了实现医疗器械表面高效、长时、安全的清洁,研究者提出主–被动协同抑菌改性方法,将化学杀菌方法与抗黏附抑菌方法相结合,充分发挥2种方法的优势,这是未来研究的重点。