A creatively designed novel two-step enhancement technique is presented in which B vitamin molecules are dynamically adsorbed onto the surface of silver nanoparticles by sodium borohydride, followed by local plasmon resonance in the presence of cations (calcium ions), ultimately achieving synergistic chemical and physical enhancement on the same molecule and constructing a "surface hot spots" two-step enhancement platform for vitamin detection. The Raman signal of the promoted vitamin molecule is enhanced by nine orders of magnitude. In a subsequent study it was observed that the vitamin B2 molecules were in a near-vertical image on the surface of the silver nanoparticles, which may also contribute to the Raman signal enhancement. Combined with deep learning techniques, the method has been successfully applied to the detection of B vitamins in body fluids. As an accurate, rapid, reproducible, non-invasive, and versatile assay platform, it holds great promise for the intelligent identification of trace B molecules in food, pharmaceuticals, and the human body.

Background: Low vitamin B-6 status has been linked to depressive symptomatology. We examined the longitudinal association of vitamin B-6 status with depressive symptomatology across 3-time points over ∼5-7 years in a cohort of older Hispanic adults. Methods: We used two-level hierarchical linear regression models for continuous outcomes. Vitamin B-6 status was associated with depressive symptomatology across these time points. Results: Plasma pyridoxyl-5-phosphate (PLP) concentration, a time-varying predictor, was significantly associated with depressive symptomatology. Study participants with PLP deficiency, vs. optimal PLP, had higher baseline depressive symptoms (Center for Epidemiologic Studies-Depression Scale (CES-D) score of 22 ± 14, vs. 20 ± 13); this differential remained constant over time and persisted after controlling for age, sex, education, body mass index, smoking and alcohol use, other relevant nutritional factors, perceived stress, stressful life events, allostatic load, and use of antidepressant medication. However, PLP concentration was not associated with the rate of change in depressive symptomatology over time. Conclusions: Suboptimal plasma PLP is associated with higher depressive symptomatology in older Hispanic of Puerto Rican descent and this appears to persist over time. Our data suggest that identification and treatment of vitamin B-6 deficiency may be a useful preventive approach in this population.