Design, Development, and Testing of a Compact Tribocorrosion Apparatus for Biomedical Applications

Multi-assessed green sustainable chromatographic resolution of nicotine and caffeine; application to in-vitro release from a new quick mist mouth spray co-formula

The availability of well-established analytical methods is crucial to cope with the fast-ongoing research for the development of new drug delivery formulations. In this work, a rapid highly green chromatographic method was developed for the simultaneous determination of nicotine (NIC) and caffeine (CAF) to be applied for an in-vitro release study from a newly prepared quick mist mouth spray co-formula (QMS), as a complementary synergistic fast-onset relief of cravings during smoking cessation. The chromatographic resolution was accomplished on a cyano column using isocratically delivered (1.0 mL/ min) glycerol: orthophosphoric acid (OPA) (0.2 M) adjusted to pH 3.0 using 0.05 M triethylamine (5:95, v/v) and UV detection at 260 nm. Well resolved peaks of NIC and CAF were eluted at 2.1 and 3.9 min (Rs = 5.64), with linear responses between 0.1 and 20.0 µg/mL and 0.2-40.0 µg/mL, and detection limits of 0.03 and 0.07 µg/mL for NIC and CAF, respectively. The developed method showed good analytical performance (accuracy, precision, robustness, and selectivity) as well as superiority in practicality and ecological profile compared to reported methods applying GAPI, analytical eco-scale, AGREE, BAGI, and whiteness metric tool. The developed method was successfully applied for NIC and CAF determination in their pharmaceutical preparations, and artificial saliva with no significant differences from reported method results (F-test and t-test). Moreover, an in-vitro release study of NIC and CAF from QMS was performed employing the developed method that revealed diffusion-controlled release, compared to mixed diffusion/ polymer chain relaxation for marketed single component formulation, showing the superiority of QMS in reducing drug level fluctuations of NIC and CAF and improving their bioavailability.

In Vitro Tribocorrosion Evaluation of Carbide-derived Carbon (CDC) for Hip Implants

Carbide-derived carbon (CDC) was previously proposed as a surface modification method for hip implant applications since it showed excellent tribocorrosion performance under open-circuit potential (OCP) conditions. Nonetheless, a systematic evaluation of CDC's tribocorrosion properties was still missing. Therefore, our objective is to test CDC's tribocorrosion performance under various electrochemical conditions and to identify the synergism between wear and corrosion. Based on the findings, the variations in OCP for CDC (0.626 mV) is smaller than Ti6Al4V (1.91 mV), and CDC showed lower induced current than T6Al4V for all potentials, suggesting CDC is more stable than Ti6Al4V under tribocorrosive conditions. Eventually, the weight loss of Ti6Al4V (50.662±5.19 μg) was found to be significantly higher than that of CDC (4.965±5.19 μg), which agrees with the electrochemical results. In summary, CDC showed better tribocorrosion performance than Ti6Al4V and was determined as an Antagonism regime.

The role of Vitamin E in hip implant-related corrosion and toxicity: Initial outcome

In orthopedic healthcare, Total Hip Replacement (THR) is a common and effective solution to hip-related bone and joint diseases/fracture; however, corrosion of the hip implant and the release of degradation metal ions/particles can lead to early implant failure and pose potential toxicity risk for the surrounding tissues. The main objective of this work was to investigate the potential role of Vitamin E to minimize corrosion-related concerns from CoCrMo hip implants. The study focused on two questions (i) Can Vitamin E inhibit CoCrMo corrosion? and (ii) Does Vitamin E moderate the toxicity associated with the CoCrMo implant particles? In the study (i) the electrochemical experiments (ASTM G61) with different concentrations of Vitamin E (1, 2, 3 mg/ml against the control) were performed using normal saline and simulated synovial fluid (Bovine calf serum-BCS, 30 g/L protein, pH 7.4) as electrolytes. The polished CoCrMo disc (Ra 50 nm) was the working electrode. The findings suggested that both Vitamin E-Saline (45 ± 0.9%) and Vitamin E-BCS (91 ± 3%) solutions protected against implant corrosion at a Vitamin E concentration of 3 mg/ml, but Vitamin E-BCS showed protection at all Vitamin E (1-3 mg/ml) concentration levels. These results suggested that the Vitamin E and the protein present in the BCS imparted additive effects towards the electrochemical inhibition. In the study (ii) the role of Vitamin E in cytotoxicity inhibition was studied using a mouse neuroblastoma cell line (N2a) for CoCrMo particles and Cr ions separately. The CoCrMo particles were generated from a custom-built hip simulator. The alamarBlue assay results suggested that Vitamin E provides significant protection (85% and 75% proliferation) to N2a cells against CoCrMo particles and Cr ions, respectively at 1 μg/ml concentration, as compared to the control group. However, the results obtained from ROS expression and DNA fiber staining suggest that Vitamin E is only effective against CoCrMo degradation particles and not against Cr ions. In summary, the findings show that Vitamin E can minimize the corrosion processes and play a role in minimizing the potential toxicity associated with implants.

Comparison of tribocorrosion behavior between 304 austenitic and 410 martensitic stainless steels in artificial seawater

The synergism between wear and corrosion can accelerate material degradation and further shorten the service life of engineering applications.