Tailoring bisphosphonate-doped titanium films to optimally couple cellular responses and antibacterial activity for biomedical applications

Titanium (Ti) is widely utilized as an implant material; nonetheless, its integration with bone tissue faces limitations due to a patient's comorbidities. To address this challenge, we employed a strategic approach involving the growth of thin films by spin-coating and surface functionalization with etidronate (ETI), alendronate (ALE), and risedronate (RIS). Our methodology involved coating of Ti cp IV disks with thin films of TiO2, hydroxyapatite (HA), and their combinations (1:1 and 1:2 v/v), followed by surface functionalization with ETI, ALE, and RIS. Bisphosphonate-doped films were evaluated in terms of surface morphology and physical-chemical properties by techniques such as electron microscopy, confocal microscopy, and x-ray photoelectron spectroscopy. The antibacterial potential of bisphosphonates alone or functionalized onto the Ti surface was tested against Staphylococcus aureus biofilms. Primary human bone mesenchymal stem cells were used to determine in vitro cell metabolism and mineralization. Although RIS alone did not demonstrate any antibacterial effect as verified by minimum inhibitory concentration assay, when Ti surfaces were functionalized with RIS, partial inhibition of Staphylococcus aureus growth was noted, probably because of the physical-chemical surface properties. Furthermore, samples comprising TiO2/HA (1:1 and 1:2 v/v) showcased an enhancement in the metabolism of nondifferentiated cells and can potentially enhance the differentiation of osteoblastic precursors. All samples demonstrated cell viability higher than 80%. Addition of hydroxyapatite and presence of bisphosphonates increase the metabolic activity and the mineralization of human bone mesenchymal cells. While these findings hold promise, it is necessary to conduct further studies to evaluate the system's performance in vivo and ensure its long-term safety. This research marks a significant stride toward optimizing the efficacy of titanium implants through tailored surface modifications.

Effects of ergosteroside combined risedronate on fracture healing and BMP-2, BMP-7 and VEGF expression in rats

Purpose

To evaluate the effect of ergosterol combined with risedronate on fracture healing.

Methods

Sixty male Sprague Dawley fracture model rats were assigned into group A (n=20), group B (n=20), and group C (n=20) at random. All rats were fed by gavage until their sacrifice as it follows: group A with ergosteroside and risedronate, group B with risedronate, and group C with saline solution. At weeks 2 and 4, 10 rats of each group were sacrificed. Healing effect and bone tissue changes in the fractures site were assessed by using hematoxylin and eosin stain histology. Enzyme-linked immunosorbent assay was used to detect the expression of serum bone morphogenetic protein-2 (BMP-2), bone morphogenetic protein-7 (BMP-7), and vascular endothelial growth factor (VEGF). Reverse transcriptase polymerase chain reaction was applied to detect the expression of osteoprotegerin (OPG) mRNA, osteocalcin (OCN) mRNA and core-binding factor subunit-?1 (CBF-?1) mRNA.

Results

In terms of serum BMP-2, BMP-7, and VEGF expression at weeks 2 and 4 after gavage, group A < group B < group C (P<0.05). At week 4 after gavage, serum VEGF expression in the three groups harbored positive relationship with serum BMP-2 and BMP-7 expression (P<0.05). Regarding serum OPG, OCN and CBF-?1 mRNA expression at weeks 2 and 4 after gavage, group A <group B <group C (P<0.05). Hematoxylin and eosin staining results showed that the recovery effect of trabecular bone and callus in the cases of group A was better than the other two groups after intragastric administration.

Conclusion

Ergosteroside combined risedronate can patently ameliorate the healing effect of fracture in rats.

4-Hydroxy-2-pyridone Derivatives and the δ-pyrone Isostere as Novel Agents Against Mycobacterium smegmatis Biofilm Inhibitors

BACKGROUND

The treatment of a bacterial infection when the bacterium is growing in a biofilm is a vexed issue. This is because the bacteria in a biofilm behaves differently compared to the individual planktonic free-form. As a result, traditional antibacterial agents lose their activity.

OBJECTIVE

Presently, there are not many drugs that are effective against bacteria growing in biofilms. Based on literature reports, we have sought to develop novel derivatives of 4-hydroxy-2- pyridone as both antimycobacterial and antibiofilm agents.

METHODS

The pyridone derivatives were synthesized by reacting 4-hydroxy-6-methyl-2H-pyran-2- one with appropriate amines and followed by reaction with substituted phenyl isocyanates as reported in the literature.

RESULTS

Four compounds in this series significantly inhibit the growth and formation of biofilm by Mycobacterium smegmatis (mc2 155 strain) at 50 µg/ml. Further, in silico evaluation of the ADME parameters shows that these compounds possess good drug-like properties and have the potential to be developed both as antibiofilm and as oral antimycobacterial agents.

CONCLUSION

This finding is of significance as presently very few small molecules are known to inhibit biofilm formation in mycobacteria. These compounds are unique in the sense that they are more potent against Mycobacterium smegmatis in the biofilm state compared to the planktonic form.

Synthesis and biological evaluation of novel acyclic and cyclic glyoxamide based derivatives as bacterial quorum sensing and biofilm inhibitors

Bacteria regulate the expression of various virulence factors and processes such as biofilm formation through a chemically-mediated communication mechanism called quorum sensing. Bacterial biofilms contribute to antimicrobial resistance as they can protect bacteria embedded in their matrix from the effects of antibiotics. Thus, developing novel quorum sensing inhibitors, which can inhibit biofilm formation, is a viable strategy to combat antimicrobial resistance. We report herein the synthesis of novel acyclic and cyclic glyoxamide derivatives via ring-opening reactions of N-acylisatins. These compounds were evaluated for their quorum sensing inhibition activity against P. aeruginosa MH602 and E. coli MT102. Compounds 20, 21 and 30 displayed the greatest quorum sensing inhibition activity against P. aeruginosa MH602, with 71.5%, 71.5%, and 74% inhibition, respectively, at 250 μM. Compounds 18, 20 and 21 exhibited the greatest QSI activity against E. coli MT102, with 71.5%, 72.1% and 73.5% quorum sensing inhibition activity, respectively. In addition, the biofilm inhibition activity was also investigated against P. aeruginosa and E. coli at 250 μM. The glyoxamide compounds 16, 18 and 19 exhibited 71.2%, 66.9%, and 66.5% inhibition of P. aeruginosa biofilms, respectively; whereas compounds 12, 20, and 22 showed the greatest inhibitory activity against E. coli biofilms with 87.9%, 90.8% and 89.5%, respectively. Finally, the determination of the in vitro toxicity against human MRC-5 lung fibroblast cells revealed that these novel glyoxamide compounds are non-toxic to human cells.