Acoustic sorting of microfluidic droplets at kHz rates using optical absorbance

Droplet microfluidics allows one to address the ever-increasing demand to screen large libraries of biological samples. Absorbance spectroscopy complements the golden standard of fluorescence detection by label free target identification and providing more quantifiable data. However, this is limited by speed and sensitivity. In this paper we increase the speed of sorting by including acoustofluidics, achieving sorting rates of target droplets of 1 kHz. We improved the device design for detection of absorbance using fibre-based interrogation of samples with integrated lenses in the microfluidic PDMS device for focusing and collimation of light. This optical improvement reduces the scattering and refraction artefacts, improving the signal quality and sensitivity. The novel design allows us to overcome limitations based on dielectrophoresis sorting, such as droplet size dependency, material and dielectric properties of samples. Our acoustic activated absorbance sorter removes the need for offset dyes or matching oils and sorts about a magnitude faster than current absorbance sorters.

Influence of variation in eumelanin content on absorbance spectra of liquid skin-like phantoms

The attenuation behavior of two different types of skin-like phantoms representing the range of Fitzpatrick skin Types I-VI was investigated and compared with real human skin. Intralipid (IL) and Pheroid(™) artificial lipid membrane vesicles, respectively, were added to synthetic eumelanin concentrations ranging from 0.0044 to 0.13mgmL(-1) to produce skin-like phantoms. Spectrophotometric absorbance and transmittance measurements were performed. Results indicated some of the nonmonotonic trends observed in real human skin, albeit shifted more toward the visible wavelength range. There exists, however, an underlying difference in interaction between the melanin and the Pheroid(™) and IL skin-like phantoms.

Minocycline in the treatment of non-gonococcal urethritis

108 male patients with non-gonococcal urethritis have been treated with minocycline given as two 100 mg. tablets initially, followed by one tablet twice a day over a period of 6 days (13 tablets). Of 96 patients followed, re-treatment for non-gonococcal urethritis within 3 months was undertaken in ten (10.4 per cent.). The findings are compared with those previously reported in seven series involving six other tetracyclines and with nine other treatment regimens. All of the tetracyclines proved superior to other agents and the best results combined with simplicity of administration were obtained with minocycline. Two patients complained of soreness of the mouth after 1 week but no other side-effects were reported. Minocycline thus gives excellent results in the treatment of non-gonococcal urethritis. In the dosage used it was also successful against gonorrhoea in seven patients treated. It is therefore particularly useful in cases in which gonorrhoea is suspected but not found in the smears or in which the smears cannot be read immediately.