ABSTRACT
Hydrogen peroxide (H2O2) plays a role in many facets - a household item, an important industrial chemical, a biomarker in vivo, and several others. For this reason, its measurement and quantification in a variety of media are important. While spectroscopic detection is primarily used for H2O2, electrochemical methods offer advantages in versatility, cost, and sensitivity. In this work, we investigate a 2-step surface metal nanoparticle (NP) modification for platinum (Pt) and palladium (Pd) on boron-doped diamond (BDD) electrodes for the detection of H2O2. Several parameters such as the metal salt concentration and electrodeposition charge in the 2-step modification were varied to find an optimum. Using cyclic voltammetry (CV), the BDD-PdNP electrode types were found to yield a sharper, more well-resolved H2O2 oxidation peak compared to the BDD-PtNP electrodes. Both metal NP electrode types significantly improved the response compared to the bare BDD electrode; a 150-200× improvement in sensitivity was observed across all modified electrode types. Calibration experiments were completed at both low and high concentration ranges in stagnant and flow-based solutions. The lowest limit of detection (LOD) obtained was 50 nM (5E-08 M) on a BDD-PdNP electrode modified with 1.0 mM PdCl2 to 5.0 mC in the wet chemical seeding and electrodeposition steps. 0.25 mM PdCl2 to 3.23 mC and 0.25 mM HPtCl6- to 3.23 mC also yielded a sufficient response for low-level H2O2, with LODs around 100 nM (1E-07 M). Overall, this work exemplifies the wide applicability of BDD and achieves sub-µM H2O2 LODs with a non-enzymatic electrode material.
ABSTRACT
BACKGROUND & AIMS: Due to ageing of the global population, hepatocellular carcinoma (HCC) is increasingly common among elderly patients, but outcomes after curative hepatic resection are unclear. Using a metanalytic approach, we aimed to estimate overall survival (OS), recurrence free survival (RFS) and complication rates in elderly HCC patients undergoing resection. METHODS: We searched PubMed, Embase, and Cochrane databases from inception to Nov 10, 2020 for studies reporting outcomes in elderly (age ≥ 65 years) patients with HCC undergoing curative surgical resection. Pooled estimates were generated using a random-effects model. RESULTS: We screened 8,598 articles and included 42 studies (7,778 elderly patients). The mean age was 74.45 years (95% CI 72.89-76.02), 75.54% were male (95% CI 72.53-78.32) and 66.73% had cirrhosis (95% CI 43.93-83.96). The mean tumor size was 5.50 cm (95% CI 4.71-6.29) and 16.01% had multiple tumors (95% CI 10.74-23.19). The 1-year (86.02% versus 86.66%, p=0.84) and 5-year OS (51.60% versus 53.78%) between non-elderly versus elderly patients were similar. Likewise, there were no differences in the 1-year (67.32% versus 73.26%, p=0.11) and 5-year RFS (31.57% versus 30.25%, p=0.67) in non-elderly versus elderly patients. There was a higher rate of minor complications (21.95% versus 13.71%, p=0.03) among elderly patients compared with non-elderly patients, but no difference in major complications (p=0.43) Conclusion: This data shows that overall survival, recurrence and major complications after liver resection for HCC are comparable between elderly and non-elderly patients, and may inform clinical management of HCC in this population.
