Practical control of SERRS enhancement.

The demonstration that quantitative and sensitive analysis can be carried out using surface enhanced resonance Raman scattering (SERRS) prompted a discussion and investigation of the main variables which are within the control of the analyst using colloidal silver as the substrate. Previous papers have dealt with the crucial need to obtain good chemisorption of the analyte to the surface and have reported the use of specially designed dyes for SERRS. One of the most variable processes is the aggregation of the colloid. Here, we investigate the addition of controlled amounts of an organic aggregating agent, poly-L-lysine, at concentrations which reduce the zeta potential in a controlled manner, thus aiding aggregation control. The relationship between the excitation frequency, the surface plasmon resonance frequency of the silver colloid and the frequency of the maximum absorbance of the molecular chromophore is studied using low concentrations of dye and no aggregating agent. Under these conditions, little to no aggregation is expected. The magnitude of the enhancement is strongly dependent on the frequency of the molecular chromophore as well as the plasmon resonance frequency. However, when sodium chloride is used to aggregate the colloid, a larger enhancement is obtained and the strong dependence on the molecular chromophore largely disappears. A much broader enhancement profile is obtained which appears to be related more to the specific enhancement processes caused by aggregation than the frequency of the chromophore. However, the total enhancement for SERRS is higher than for SERS thus indicating that the chromophore is still important to the process.

Antibiotic iontophoresis in the treatment of ear chondritis.

This apparently successful management of suppurative ear chondritis by employing antibiotic iontophoresis does suggest a clinical potential for the use of the procedure. The authors recommend further research to document the efficacy of this procedure as this clinical report does not involve a large sample or sufficient experimental controls, such as selection of medication, dosage values, and confirmation of tissue content of the medication. Factors favoring the trial use of antibiotic iontophoresis, particularly before the permanent disfigurement of extensive chondrectomy or amputation, are 1) reported past experimental confirmation of the effectiveness of iontherapy, 2) the expected small incidence of procedural complications, 3) the ease of application, and 4) the usual absence of discomfort.