Characterization and bacterial anti-adherent effect on modified PMMA denture acrylic resin containing platinum nanoparticles

PURPOSE

This study characterized the synthesis of a modified PMMA (Polymethyl methacrylate) denture acrylic loading platinum nanoparticles (PtN) and assessed its bacterial inhibitory efficacy to produce novel antimicrobial denture base material.

MATERIALS AND METHODS

Polymerized PMMA denture acrylic disc (20 mm × 2 mm) specimens containing 0 (control), 10, 50, 100 and 200 mg/L of PtN were fabricated respectively. The obtained platinum-PMMA nanocomposite (PtNC) was characterized by TEM (transmission electron microscopy), SEM/EDX (scanning electron microscope/energy dispersive X-ray spectroscopy), thermogravimetric and atomic absorption spectrophotometer analysis. In antimicrobial assay, specimens were placed on the cell culture plate, and 100 µL of microbial suspensions of S. mutans (Streptococcus mutans) and S. sobrinus (Streptococcus sobrinus) were inoculated then incubated at 37℃ for 24 hours. The bacterial attachment was tested by FACS (fluorescence-activated cell sorting) analysis after staining with fluorescent probe.

RESULTS

PtN were successfully loaded and uniformly immobilized into PMMA denture acrylic with a proper thermal stability and similar surface morphology as compared to control. PtNC expressed significant bacterial anti-adherent effect rather than bactericidal effect above 50 mg/L PtN loaded when compared to pristine PMMA (P=.01) with no or extremely small amounts of Pt ion eluted.

CONCLUSION

This is the first report on the synthesis and its antibacterial activity of Pt-PMMA nanocomposite. PMMA denture acrylic loading PtN could be a possible intrinsic antimicrobial denture material with proper mechanical characteristics, meeting those specified for denture bases. For clinical application, future studies including biocompatibility, color stability and warranting the long-term effect were still required.     

纳米炭混悬液在甲状腺乳头状癌中央组淋巴结清扫中的应用

目的 探讨甲状腺乳头状癌中央组淋巴结清扫术中使用纳米炭混悬液的意义.方法 甲状腺乳头状癌中央组淋巴结清扫术中使用纳米炭混悬液病例45例(淋巴结示踪组),与同期术中未使用纳米炭混悬液病例49例(空白对照组)在清扫淋巴结数目、手术时间、术中出血量、术后引流量、甲状旁腺功能等方面进行比较.结果 淋巴结示踪组手术时间为(80.47±9.23) min、术中出血量为(35.53±7.43)ml、术后引流量为(71.09±12.18) ml;空白对照组手术时间为(84.65±12.01) min、术中出血量为(35.14±9.08) ml、术后引流量为(69.37±15.38) ml,两组比较差异无统计学意义(P＞0.05);淋巴结示踪组术后低钙发生率(4.4％)低于空白对照组(20.4％,P＜0.05);淋巴结示踪组术后1d甲状旁腺激素(PTH)水平[(35.36±18.35) ng/L]高于空白对照组[(26.58±15.80) ng/L,P＜0.05]、淋巴结示踪组术后1周PTH水平[(37.67±17.29) ng/L]高于空白对照组[(28.06±17.15) ng/L,P＜0.01];淋巴结示踪组手术切除淋巴结的数目(9.40±2.35)枚多于空白对照组[(7.86±2.06)枚,P＜0.01].结论 术中使用纳米炭混悬液并未增加手术时间、术后引流量及术后并发症,提高了中央组淋巴结清扫的数目,同时有助于识别甲状旁腺并保护甲状旁腺功能.     

Biodegradable nanocomposite microparticles as drug delivering injectable cell scaffolds

Injectable cell scaffolds play a dual role in tissue engineering by supporting cellular functions and delivering bioactive molecules. The present study aimed at developing biodegradable nanocomposite microparticles with sustained drug delivery properties thus potentially being suitable for autologous stem cell therapy. Semi-crystalline poly(l-lactide/dl-lactide) (PLDL70) and poly(l-lactide-co-glycolide) (PLGA85) were used to prepare nanoparticles by the double emulsion method. Uniform and spherical nanoparticles were obtained at an average size of 270-300 nm. The thrombin receptor activator peptide-6 (TRAP-6) was successfully loaded in PLDL70 and PLGA85 nanoparticles. During the 30 days' release, PLDL70 nanoparticles showed sustainable release with only 30% TRAP-6 released within the first 15 days, while almost 80% TRAP-6 was released from PLGA85 nanoparticles during the same time interval. The release mechanism was found to depend on the crystallinity and composition of the nanoparticles. Subsequently, mPEG-PLGA nanocomposite microparticles containing PLDL70 nanoparticles were produced by the ultrasonic atomization method and evaluated to successfully preserve the intrinsic particulate properties and the sustainable release profile, which was identical to that of the nanoparticles. Good cell adhesion of the human fibroblasts onto the nanocomposite microparticles was observed, indicating the desired cell biocompatibility. The presented results thus demonstrate the development of nanocomposite microparticles tailored for sustainable drug release for application as injectable cell scaffolds.     

纳米碳在cNO期甲状腺乳头状癌中央区淋巴结清扫手术中的应用

目的研究纳米碳混悬液示踪技术在cN0期甲状腺乳头状癌中央区淋巴结清扫手术中的应用价值。方法将2012年5～10月期间在笔者所在医院科室治疗的68例cN0期甲状腺乳头状癌患者随机分为2组：未使用纳米碳淋巴示踪剂（对照组）32例,使用纳米碳淋巴示踪剂（示踪组）36例,均行甲状腺全切除术、患侧和（或）对侧中央区（Ⅵ区）淋巴结清扫术。比较2组患者的淋巴结清扫数、淋巴结转移情况以及手术相关指标（手术时间、术中出血量、术后引流时间和住院时间）。结果对照组和示踪组分别清扫中央区淋巴结205枚和324枚。其中,对照组手术清扫中央区淋巴结（6．41±1．56）枚／例,示踪组为（8．99±2．24）枚／例,多于对照组（P〈0．001）。对照组的中央区淋巴结转移率为40．6％（13／32）,与示踪组（47．2％,17／36）相比差异无统计学意义（P=0．762）,但示踪组喉返神经内侧区的淋巴结转移率（38．9％,14／36）高于对照组（12．5％,4／32）,P=0．029。2组患者的手术时间、术中出血量、术后引流时间、住院时间、术后切口出血发生率、一过性低血钙发生率及喉上神经损伤发生率比较差异均无统计学意义（P〉0．05）。2组患者术后均随访6个月,均无术后肿瘤复发、转移及死亡发生。结论纳米碳淋巴示踪技术可明显提高cN0期甲状腺乳头状癌患者中央区淋巴结的清扫数目,能比较准确地反映淋巴结的转移情况,从而对肿瘤进行准确的分期,以指导术后治疗,同时不增加（或延长）术中出血量、手术时间、术后住院时间及手术并发症发生率。     

MR imaging,targeting and characterization of pulmonary fibrosis using intra‐tracheal administration of gadolinium‐based nanoparticles

Idiopathic pulmonary fibrosis is a devastating disease. Animal models are critical to develop new diagnostic approaches. We investigate here whether the application of an ultra‐short echo time MRI sequence combined with the intra‐tracheal administration of Gd‐based nanoparticles can help to visualize and characterize pulmonary fibrosis in mice. 21 mice were imaged. Treated mice were administered bleomycin. MRI was used for longitudinal detection of bleomycin‐induced lung injury from Day 1 up to Day 60. On Day 30, all mice received nanoparticles and MR images were acquired. A signal enhancement of 120% and 50% in fibrotic lesions and healthy tissues respectively was obtained. A twofold increase of contrast‐to‐noise ratio between fibrotic and healthy tissue was also observed, leading to a more accurate delineation of the extent of fibrosis. The elimination time constant of the nanoparticles was 54% higher in fibrotic lesions. Bleomycin‐induced lung injury can be monitored using MRI. Intra‐tracheal administration of Gd‐based nanoparticles enabled us to enhance fibrotic tissue in lungs but also to extract imaging biomarkers that quantify elimination and diffusion of contrast agents and can characterize fibrotic tissue. The added value of MRI associated with pulmonary administration of contrast agents is key to better understand the lung fibrotic process and monitor drug response in pre‐clinical studies, which will be valuable for translational applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Specific targeting and noninvasive magnetic resonance imaging of an asthma biomarker in the lung using polyethylene glycol functionalized magnetic nanocarriers

Simultaneous inhibition of IL4 and IL13 via the common receptor chain IL4Rα to block adequately their biologic effects presents a promising therapeutic approach to give the additional relief required for asthma patients. In this study, superparamagnetic iron oxide nanoparticles were conjugated with anti‐IL4Rα blocking antibodies via polyethylene glycol (PEG) polymers. The delivery of these blocking antibodies to the inflammatory sites in the lung via the developed nanocarriers was assessed using noninvasive free‐breathing pulmonary MRI. Biocompatibility assays confirmed the safety of the developed nanocarriers for pre‐clinical investigations. For all the investigated formulations, nanocarriers were found to be very stable at neutral pH. However, the stability noticeably decreased with the PEG length in acidic environment and thus the loaded antibodies were preferentially released. Immunofluorescence and fluorimetry assays confirmed the binding of the nanocarriers to the IL4Rα asthma biomarker. Pulmonary MRI performed using an ultra‐short echo time sequence allowed simultaneous noninvasive monitoring of inflammatory responses induced by ovalbumin challenge and tracking of the developed nanocarriers, which were found to colocalize with the inflammatory sites in the lung. Targeting of the developed nanocarriers to areas rich in IL4Rα positive inflammatory cells was confirmed using histological and flow cytometry analyses. The anti‐IL4Rα‐conjugated nanocarriers developed here have been confirmed to be efficient in targeting key inflammatory cells during chronic lung inflammation following intrapulmonary administration. Targeting efficiency was monitored using noninvasive MRI, allowing detection of the nanocarriers’ colocalizations with the inflammatory sites in the lung of ovalbumin‐challenged asthmatic mice. Copyright © 2015 John Wiley & Sons, Ltd.     

Nanodiagnostics for tuberculosis detection

Introduction: Tuberculosis (TB) is a leading killer worldwide. End TB strategy aims at ending the TB epidemic by 2030. Early, accurate, and affordable diagnosis represents a cornerstone to achieve this goal. Innovative strategies for TB diagnostics have been introduced. However, the ideal assay is yet unavailable and conventional methods remain necessary for diagnosis. Unique properties of nanoparticles (NPs) have allowed their utilization in TB detection via targeting disease biomarkers.

Area covered: Until now, around thirty-five TB NP-based assays have been partially or fully characterized. Accuracy, low-cost, and short time-to-result represent the common properties of proposed platforms. TB nanodiagnostics now encompass almost all clinical aspects of the disease including active TB, non-tuberculous mycobacteria, rifampicin resistant TB, TB/HIV co-infection, latent TB, and extra-pulmonary TB. This review summarizes state-of-the-art knowledge of TB nanodiagnostics for the last 10 years. Special consideration is given for fabrication concepts, detection strategies, and clinical performance using various clinical specimens. The potential of TB nanodiagnostics to fulfill the need for ideal MTB testing is assessed.

Expert commentary: TB nanodiagnostics show promise to be ideal detection tools that can meet the rigorous demands to end the TB epidemic by 2030.     

基于NaGdF_4:Yb,Er纳米颗粒的磁共振/上转换发光双模态探针的构建及胰腺癌体内成像研究

目的制备以顺磁性稀土纳米颗粒为基质的高发光强度上转换纳米颗粒,并对其表面生物相容性及功能化修饰,分析肿瘤靶向纳米探针在胰腺癌诊断的成像应用,为下一步术中导航奠定基础。方法采用高温法合成NaGdF_4:Yb,Er纳米颗粒,表面构建核壳结构,外修饰聚乙二烯(PEG)以增强发光强度及生物相容性,耦联靶向基团实现胰腺癌特异性组织识别。通过胰腺癌原位动物模型开展磁共振/上转换发光双模态成像及病理学评估。结果标准化Er~(3+)粒子浓度以后,包壳后纳米颗粒的整体发光强度是包壳前的70倍,平均粒径为(18.6±0.9)nm。耦联靶向基团后水合尺寸明显增大,但未出现其他峰位。靶向探针在体外实验中较对照组有明显T1信号增强作用。MRI成像结果,探针于肿瘤T1增强的峰值时间出现在注射后4 h,肿瘤区域T1信号下降达79%。上转换成像结果,上转换发光峰值时间也出现在第4小时,之后随时间持续下降。探针组织分布大部分集中在正常肺脏,但摄取量很低,不及注射总量的10%,表现出很好的安全性。结论基于上转换发光纳米颗粒探针,在体内能够实现胰腺癌的检测,展现出了在早期胰腺癌诊断及术中导航的临床转化价值。     

磁性氧化铁纳米探针用于肿瘤靶向磁共振成像的研究现状

超顺磁性氧化铁纳米粒子（SPIONs）粒径小,穿透性强,常用于制备分子成像探针或MRI对比剂。近年来,国内外对纳米修饰的肿瘤靶向性磁性氧化铁探针研究越来越多。本文对SPIONs探针的合成、表面修饰及其生物医学应用进展进行综述。     

不同粒径的Au纳米粒子对SPR技术定量分析灵敏度的影响

目的通过比较不同粒径金纳米粒子(Au NPs)对表面等离子共振(surface plasmon resonance,SPR)系统信号放大的影响,筛选最适粒径的Au NPs,从而建立一种新的SPR方法用于猕猴血清中西妥昔单抗(C225)定量分析。方法利用柠檬酸还原HAuCl4法自行制备3种粒径Au NPs并分别与羊抗人IgG进行偶联,将偶联物引入BI-Acore系统进行SPR信号采集,筛选最适粒径的Au NPs,进而利用BIAcore系统建立猕猴体内C225定量分析标准曲线。结果自行制备的Au NPs形状相对圆润,大小均一。几种粒径的Au NPs均能引起SPR信号放大,但粒径不同则SPR信号放大情况不同,其中10 nm Au NPs的SPR信号放大作用最为明显。结论将特定大小的Au NPs引入SPR定量分析系统能够显著提高SPR信号强度,从而进一步提高SPR定量分析灵敏度。