Conjugation of Ciprofloxacin with Poly(2-oxazoline)s and Polyethylene Glycol via End Groups.

The antibiotic ciprofloxacin (CIP) was covalently attached to the chain end of poly(2-methyloxazoline) (PMOx), poly(2-ethyloxazoline) (PEtOx), and polyethylene glycol (PEG), and the antimicrobial activity of these conjugates was tested for Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Pseudomonas aeruginosa, and Kleisella pneumoniae. Chemical structures of the conjugates were proven by (1)H NMR and electron spray ionization mass spectrometry. The direct coupling of PMOx and CIP resulted in low antimicrobial activity. The coupling via a spacer afforded molecular weight dependent activity with a molar minimal inhibitory concentration that is even higher than that of the pristine CIP. The antimicrobial activity of the conjugates increases in the order of PMOx < PEtOx < PEG. Conjugation of CIP and a quaternary ammonium compound via PMOx did not result in higher activity, indicating no satellite group or synergistic effect of the different biocidal end groups.

Detection of metabolites of trapped humans using ion mobility spectrometry coupled with gas chromatography.

For the first time, ion mobility spectrometry coupled with rapid gas chromatography, using multicapillary columns, was applied for the development of a pattern of signs of life for the localization of entrapped victims after disaster events (e.g., earthquake, terroristic attack). During a simulation experiment with entrapped volunteers, 12 human metabolites could be detected in the air of the void with sufficient sensitivity to enable a valid decision on the presence of a living person. Using a basic normalized summation of the measured concentrations, all volunteers involved in the particular experiments could be recognized only few minutes after they entered the simulation void and after less than 3 min of analysis time. An additional independent validation experiment enabled the recognition of a person in a room of ∼25 m(3) after ∼30 min with sufficiently high sensitivity to detect even a person briefly leaving the room. Undoubtedly, additional work must be done on analysis time and weight of the equipment, as well as on validation during real disaster events. However, the enormous potential of the method as a significantly helpful tool for search-and-rescue operations, in addition to trained canines, could be demonstrated.

Breath analysis-performance and potential of ion mobility spectrometry.

Ion mobility spectrometry is a fast and sensitive analytical method for the detection of gas phase analytes in the ppb(v)-ppt(v) range under ambient conditions (pressure and temperature). Ion mobility spectrometers coupled with rapid pre-separation like multi-capillary columns (MCC/IMS) are suitable for the selective characterization of complex and humid mixtures. Recently, MCC/IMS have been applied to analyses of human breath for early diagnosis as well as medication and therapy control. The complete procedure of breath analyses including evaluation and interpretation of the data obtained is demonstrated for the first time on exhaled breath after the consumption of a particular candy as an example. An MCC/IMS equipped with a ß-radiation source ((63)Ni) requires 5 to 10 min for a complete analysis of exhaled breath. Retention time and reduced ion mobility of the detected signals are compared to an analyte database for the identification of the related analytes. These findings were successfully validated by gas-chromatographic mass spectroscopy of the headspace of the candy via solid-phase micro-extraction and of breath samples on Tenax adsorption tubes. Furthermore, signal height of particular analyte signals as a measure for their concentration was used to monitor the concentration development with time. This exemplary investigation demonstrates that MCC/IMS is a powerful and rapid non-invasive tool for human breath analyses. The method can be used for medical applications (diagnosis, therapy control, metabolic profiling) as well as for a general determination of the metabolic state of a subject (medication, nutrition, fasting). The demonstrated procedure is independent of whether the analytes detected in breath are caused by nutrition or medication or whether they are metabolite characteristics for a particular disease. Therefore, it can directly be transferred to any relevant peak pattern.