Chen Kexun, Ustriyana Putu, Moore Francisco, Sahai Nita
Department of Polymer Science, The University of Akron, 170 University Avenue, Akron, Ohio 44325-3909, United States.
Department of Biology, The University of Akron, 235 Carroll Street, Akron, Ohio 44325-3908, United States.
ACS Biomater Sci Eng. 2019 Feb 11;5(2):561-571. doi: 10.1021/acsbiomaterials.8b00996. Epub 2019 Jan 29.
Hydroxyapatite (HAP) is an extensively used orthopedic biomaterial because of its high biocompatibility and osteoconductivity. Implant-related infection is a major cause of orthopedic device failure. Previous research showed that silver-doped hydroxyapatite nanoparticles (Ag-HAP NPs) have prominent antimicrobial activity, but their biocompatibility and plasma protein response remained unexplored. Here we investigated the effects of synthesis conditions on Ag-HAP NP antimicrobial ( and ) activity, biocompatibility, and the adsorption of two blood plasma proteins, human serum albumin (HSA) and fibrinogen (Fib). It was found that synthesis pH affected the Ag content of Ag-HAP NPs and subsequent Ag release from the NPs in solution. This, in turn, affected antimicrobial efficiency and cytotoxicity to murine preosteoblast cells (MC3T3-E1). More HSA than Fib was adsorbed on a molar basis. The conformation of HSA changed drastically from predominantly α-helix and minor β-sheet content in solution to greater β-sheet than α-helix content when adsorbed. Correspondingly, the melting temperature of HSA changed significantly from 76 °C in solution to ∼65-66 °C when adsorbed. Fib exhibited a modest decrease in α-helix content while the β-sheet content increased modestly upon adsorption and its remained unchanged at ∼60 °C. These differences in behavior of HSA and Fib are ascribed to the much smaller size of HSA, which allows a greater molecular packing density on the surface, which induces greater conformational changes. The protein adsorption behavior on Ag-HAP was similar to that on pure HAP. Thus, we show that Ag-HAP NPs have antimicrobial activity without deleterious effects on biocompatibility and blood plasma protein adsorption.
羟基磷灰石（HAP）因其高生物相容性和骨传导性而成为广泛应用的骨科生物材料。植入相关感染是骨科器械失效的主要原因。先前的研究表明，银掺杂羟基磷灰石纳米颗粒（Ag-HAP NPs）具有显著的抗菌活性，但其生物相容性和血浆蛋白反应仍未得到探索。在此，我们研究了合成条件对Ag-HAP NPs抗菌活性、生物相容性以及两种血浆蛋白——人血清白蛋白（HSA）和纤维蛋白原（Fib）吸附的影响。结果发现，合成pH值影响Ag-HAP NPs的银含量以及随后银从纳米颗粒在溶液中的释放。这进而影响抗菌效率和对小鼠前成骨细胞（MC3T3-E1）的细胞毒性。以摩尔为基础，吸附的HSA比Fib更多。HSA的构象从溶液中主要为α-螺旋和少量β-折叠含量急剧变化为吸附时β-折叠含量大于α-螺旋含量。相应地，HSA的解链温度从溶液中的76℃显著变化为吸附时的约65 - 66℃。Fib在吸附时α-螺旋含量适度降低，而β-折叠含量适度增加，其解链温度在约60℃保持不变。HSA和Fib行为的这些差异归因于HSA小得多的尺寸，这使得其在表面具有更高的分子堆积密度，从而诱导更大的构象变化。Ag-HAP上的蛋白质吸附行为与纯HAP上的相似。因此，我们表明Ag-HAP NPs具有抗菌活性，且对生物相容性和血浆蛋白吸附没有有害影响。
