Surface Functionalisation of Dental Implants with a Composite Coating of Alendronate and Hydrolysed Collagen: DFT and EIS Studies

Abstract

The success of the osseointegration process depends on the surface characteristics and chemical composition of dental implants. Therefore, the titanium dental implant was functionalised with a composite coating of alendronate and hydrolysed collagen, which are molecules with a positive influence on the bone formation. The results of the quantum chemical calculations at the density functional theory level confirm a spontaneous formation of the composite coating on the titanium implant, ∆G*INT = −8.25 kcal mol−1. The combination of the results of X-ray photoelectron spectroscopy and quantum chemical calculations reveals the structure of the coating. The alendronate molecules dominate in the outer part, while collagen tripeptides prevail in the inner part of the coating. The electrochemical stability and resistivity of the implant modified with the composite coating in a contact with the saliva depend on the chemical nature of alendronate and collagen molecules, as well as their inter- and intramolecular interactions. The formed composite coating provides a 98% protection to the implant after the 7-day immersion in the artificial saliva. From an application point of view, the composite coating could effectively promote osseointegration and improve the implant’s resistivity in contact with an aggressive environment such as saliva.

Alendronate as Bioactive Coating on Titanium Surfaces: An Investigation of CaP–Alendronate Interactions

“…The surface characterization (composition) of Ti/oxide/alendronate samples before and after immersion was performed using ATR-FTIR ( Figure 5 ). Prior to sample immersion, weak bands around 1000 cm –1 are visible characteristics for the P–O and P=O bands present in the alendronate molecule [ 16 , 56 , 57 ]. On the other hand, after immersion bands were detected in the spectral range from 900 to 1100 cm –1 , typical for the symmetric and asymmetric P–O stretching modes in the phosphate group [ 58 , 59 , 60 ].…”

“…Organophosphorus compounds such as phosphonates have proven to be effective agents for the functionalization of titanium surfaces by forming homogeneous self-assembled monolayers. In particular, alendronate, a nitrogen-containing bisphosphonate, exhibits good coating properties on titanium surfaces [ 15 , 16 , 17 ], and the effect of immobilizing alendronate on the titanium surface to stimulate new bone formation and improve bone-implant integration after implantation has been widely reported [ 17 , 18 , 19 , 20 ]. On the titanium surface, alendronate molecules are covalently bound to the TiO 2 layer via phosphonate groups (-PO 3 H) [ 15 ].…”

“…In our previous publications, the mechanism of the formation of the alendronate coating on the titanium surface and its chemical stability when exposed to artificial saliva was reported in detail [ 15 , 16 ]. Since the alendronate-modified titanium surface has been shown to exhibit good chemical stability, which is the basic prerequisite for its biocompatibility, it was of great importance to investigate bioactivity as an essential property for successful osseointegration.…”

Titanium Implant Alloy Modified by Electrochemically Deposited Functional Bioactive Calcium Phosphate Coatings

“…The EEC and titanium alloy | surface film interface are schematically presented in Figure 6a,b, respectively. The used EEC has previously been published for surface film-covered titanium and its alloys [46,[68][69][70][71].…”