Conjugation of antibiotics with polymers is an emerging strategy to improve the performance of these important drugs. Here, the antibiotic ciprofloxacin (CIP) was conjugated with amphiphilic poly­(2-oxazoline) (POx) block copolymers to investigate whether the activity of the antibiotic was enhanced due to additionally induced membrane activity. The resulting polymer–antibiotic conjugates (PACs) are an order of magnitude more active against the bacterial strain Staphylococcus aureus than CIP and show high activities against numerous pathogenic bacterial strains. Their high activity depends on an optimal hydrophobic/hydrophilic balance (HHB) of the POx tail. Mechanistic studies revealed that the derivatization of CIP required for the polymer conjugation lowers the affinity of the antibiotic to its target topoisomerase IV. However, the amphiphilic PACs are most likely concentrated within the bacterial cytoplasm, which overcompensates the loss of affinity and results in high antibacterial activity. In addition, the development of resistance in S. aureus and Escherichia coli is slowed down. More importantly, the amphiphilic PACs are active against CIP-resistant S. aureus and E. coli. The PACs with the highest activity are not cytotoxic toward human stem cells and do not lyse blood cells in saturated solution.

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This book analyses the provision of personnel in the context of a mixed contract and employee leasing from the perspective of employment law. This analysis was motivated by decisions by the Bundesarbeitsgericht (German Federal Labour Court) on aircraft leasing including the provision of aircraft personnel (wet lease). The Arbeitnehmerüberlassungsgesetz (Germany’s law on labour leasing) and the relevant provisions in European Union law are defined and discussed. Until now, there has been no academic analysis of this issue on this broad scale. Based on the results, a new concept is presented, which is intended to provide a basis for the assessment of this contractual constellation. On the example of wet lease contracts, the new assessment method is applied and discussed.

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