Ghensi Paolo, Bettio Elia, Maniglio Devid, Bonomi Emiliana, Piccoli Federico, Gross Silvia, Caciagli Patrizio, Segata Nicola, Nollo Giandomenico, Tessarolo Francesco
Department of Cellular, Computational and Integrative Biology, University of Trento, 38122 Trento, Italy.
Department of Industrial Engineering, University of Trento, 38122 Trento, Italy.
Materials (Basel). 2019 Jul 30;12(15):2429. doi: 10.3390/ma12152429.
several strategies have been tested in recent years to prevent bacterial colonization of dental implants. Sericin, one of the two main silk proteins, possesses relevant biological activities and also literature reports about its potential antibacterial properties, but results are discordant and not yet definitive. The aim of this study was to evaluate the effectiveness of different experimental protocols in order to obtain a sericin-based coating on medical grade titanium (Ti) able to reduce microbial adhesion to the dental implant surface.
different strategies for covalent bonding of sericin to Ti were pursued throughout a multi-step procedure on Ti-6Al-4V disks. The surface of grade 5 Ti was initially immersed in NaOH solution to obtain the exposure of functional -OH groups. Two different silanization strategies were then tested using aminopropyltriethoxysilane (APTES). Eventually, the bonding between silanized Ti-6Al-4V and sericin was obtained with two different crosslinking processes: glutaraldehyde (GLU) or carbodiimide/N-Hydroxy-succinimide (EDC/NHS). Micro-morphological and compositional analyses were performed on the samples at each intermediate step to assess the most effective coating strategy able to optimize the silanization and bioconjugation processes. Microbiological tests on the coated Ti-6Al-4V disks were conducted in vitro using a standard biofilm producer strain of (ATCC 6538) to quantify the inhibition of microbial biofilm formation (anti-biofilm efficacy) at 24 hours.
both silanization techniques resulted in a significant increase of silicon (Si) on the Ti-6Al-4V surfaces etched with NaOH. Differences were found between GLU and EDC/NHS bioconjugation strategies in terms of composition, surface micro-morphology and anti-biofilm efficacy. Ti-6Al-4V samples coated with GLU-bound sericin after silanization obtained via vapor phase deposition proved that this technique is the most convenient and effective coating strategy, resulting in a bacterial inhibition of about 53% in respect to the uncoated Ti-6Al-4V disks.
The coating with glutaraldehyde-bound sericin after silanization in the vapor phase showed promising bacterial inhibition values with a significant reduction of biofilm. Further studies including higher number of replicates and more peri-implant-relevant microorganisms are needed to evaluate the applicability of this experimental protocol to dental implants.
近年来已测试了多种预防牙种植体细菌定植的策略。丝胶蛋白是两种主要丝蛋白之一，具有相关生物活性，也有关于其潜在抗菌特性的文献报道，但结果不一致且尚未明确。本研究的目的是评估不同实验方案的有效性，以便在医用级钛（Ti）上获得基于丝胶蛋白的涂层，能够减少微生物对牙种植体表面的粘附。
在Ti-6Al-4V圆盘上通过多步骤程序采用不同策略将丝胶蛋白共价结合到Ti上。5级Ti的表面最初浸入NaOH溶液中以获得官能团-OH的暴露。然后使用氨丙基三乙氧基硅烷（APTES）测试两种不同的硅烷化策略。最终，通过两种不同的交联过程：戊二醛（GLU）或碳二亚胺/N-羟基琥珀酰亚胺（EDC/NHS），实现了硅烷化的Ti-6Al-4V与丝胶蛋白之间的结合。在每个中间步骤对样品进行微观形态和成分分析，以评估能够优化硅烷化和生物共轭过程的最有效涂层策略。使用标准生物膜产生菌株（ATCC 6538）在体外对涂覆的Ti-6Al-4V圆盘进行微生物测试，以量化24小时时对微生物生物膜形成的抑制作用（抗生物膜功效）。
两种硅烷化技术均导致在经NaOH蚀刻的Ti-6Al-4V表面上硅（Si）显著增加。在组成、表面微观形态和抗生物膜功效方面，GLU和EDC/NHS生物共轭策略之间存在差异。通过气相沉积硅烷化后涂覆有GLU结合丝胶蛋白的Ti-6Al-4V样品证明，该技术是最方便有效的涂层策略，相对于未涂覆的Ti-6Al-4V圆盘，细菌抑制率约为53%。
气相硅烷化后用戊二醛结合丝胶蛋白进行涂层显示出有前景的细菌抑制值，生物膜显著减少。需要进一步的研究，包括更多的重复次数和更多与种植体周围相关的微生物，以评估该实验方案对牙种植体的适用性。
