Osteointegration, antimicrobial and antibiofilm activity of orthopaedic titanium surfaces coated with silver and strontium-doped hydroxyapatite using a novel blasting process.

Poor integration of orthopaedic devices with the host tissue owing to aseptic loosening and device-associated infections are two of the leading causes of implant failure, which represents a significant problem for both patients and the healthcare system. Novel strategies have focused on silver to combat antimicrobial infections as an alternative to drug therapeutics. In this study, we investigated the impact of increasing the % substitution (12% wt) of silver and strontium in hydroxyapatite (HA) coatings to enhance antimicrobial properties and stimulate osteoblasts, respectively. Additionally, we prepared a binary substituted coating containing both silver and strontium (AgSrA) at 12% wt as a comparison. All coatings were deposited using a novel blasting process, CoBlast, onto biomedical grade titanium (V). Surface physicochemical properties, cytocompatibility and antimicrobial functionality were determined. The anticolonising properties of the coatings were screened using Staphylococcus aureus ATCC 1448, and thereafter, the AgA coating was evaluated using clinically relevant strains. Strontium-doped surfaces demonstrated enhanced osteoblast viability; however, a lower inhibition of biofilm formation was observed compared with the other surfaces. A co-substituted AgSrA surface did not show enhanced osteoblast or anticolonising properties compared with the SrA and AgA surfaces, respectively. Due to its superior anticolonising performance in preliminary studies, AgA was chosen for further studies. The AgA coated surfaces demonstrated good antibacterial activity (eluted and immobilised ion) against methicillin-resistant S. aureus followed by methicillin-sensitive Staphylococcus aureus clinical isolates; however, the AgA surface displayed poor impact against Staphylococcus epidermidis. In conclusion, herein, we demonstrate that HA can be substituted with a range of ions to augment the properties of HA coatings on orthopaedic devices, which offer promising potential to combat orthopaedic device-associated infections and enhance device performance.

A food freshness sensor using the multistate response from analyte-induced aggregation of a cross-reactive poly(thiophene).

A single cross-reactive conjugated polymer generates a multidimensional response capable of identifying and differentiating between 22 structurally similar and biologically relevant amines with 97% accuracy in a highly competitive aqueous environment. Statistical analysis on an array of wavelengths was used to assess the viability of this approach. In a separate investigation, the multidimensional response from a single cross-responsive poly(thiophene) has been analyzed using a different ratiometric method to quantify the amount of biogenic amine present in a fish matrix, thereby evaluating the quality of the food.

Self-repairing polymers: poly(dioxaborolane)s containing trigonal planar boron.

The molecular weight of poly(dioxaborolane)s can be controlled during the polymerization reaction or through post-polymerization processing in such a manner that hydrolytic damage to these materials may be repaired, thereby regenerating the polymer.

Cross-reactive conjugated polymers: analyte-specific aggregative response for structurally similar diamines.

A single cross-reactive conjugated polymer (poly(thiophene) 1) generates unique spectral patterns in response to structurally similar diamines. Multivariate statistics are used to deconvolute subtle variations in these spectral responses, allowing for identification and quantification of the analytes with >99% accuracy.