Preparation of a Selective Receptor for Ephedrine for the Development of an Optical Spot Test for the Detection of Ephedrine in Human Urine Using Stabilized in Air Lipid Films with Incorporated Receptor

Lipid membrane-based therapeutics and diagnostics

Success rates in drug discovery are extremely low, and the imbalance between new drugs entering clinical research and their approval is steadily widening. Among the causes of the failure of new therapeutic agents are the lack of safety and insufficient efficacy. On the other hand, timely disease diagnosis may enable an early management of the disease, generally leading to better and less costly outcomes. Several strategies have been explored to overcome the barriers for drug development and facilitate diagnosis. Using lipid membranes as platforms for drug delivery or as biosensors are promising strategies, due to their biocompatibility and unique physicochemical properties. We examine some of the lipid membrane-based strategies for drug delivery and diagnostics, including their advantages and shortcomings. Regarding synthetic lipid membrane-based strategies for drug delivery, liposomes are the archetypic example of a successful approach, already with a long period of well-succeeded clinical application. The use of lipid membrane-based structures from biological sources as drug carriers, currently under clinical evaluation, is also discussed. These biomimetic strategies can enhance the in vivo lifetime of drug and delivery system by avoiding fast clearance, consequently increasing their therapeutic window. The strategies under development using lipid membranes for diagnostic purposes are also reviewed.

Preparation of a selective receptor for carbofuran for the development of a simple optical spot test for its rapid detection using stabilized in air lipid films with incorporated receptor

The present technique describes the preparation of a selective receptor for carbofuran and the development of a simple sensitive spot optical test for the rapid one-shot detection of carbofuran using stabilized lipid films supported on a methacrylate polymer on a glass fiber filter with incorporated artificial receptor. The selective receptor was synthesized by a chemical reaction using a resorcin[4]arene receptor by transforming all the -OH groups into phosphoryl groups. The lipid films without this receptor provided fluorescence under a UV lamp. The use of the receptor in these films quenched this fluorescence and the colour became similar to that of the filters without the lipid films. A drop of aqueous solution of carbofuran provided a "switching on" of the fluorescence which allows the rapid detection of this insecticide at the levels of 10(-9)M concentrations. The effect of potent interferences included a wide range of compounds. The results showed no interferences from these compounds in concentration levels usually found in real samples. The effect of interference of proteins and lipids was also examined. The reproducibility of the method was checked in about 100 samples and all of them were found to provide similar results. The device was tested/evaluated in real samples of fruits, vegetables and dairy products. Note that the colours of the filters remain stable for periods of more than 2 months.

Study of calix[4]resorcinarene–dopamine complexation in mixed phospholipid monolayers formed at the air–water interface

We have studied the physical properties of monolayers formed by calix[4]resorcinarene and in mixtures with dipalmitoyl phosphatidylcholine (DPPC) in various molar ratios formed at the air-water interface and at presence of dopamine in water subphase by means of measurements of surface pressure and dipole potential. We showed that both calix[4]resorcinarene as well as its mixture with DPPC form stable monolayers at the water subphase. The presence of dopamine resulted in an increase of the mean molecular area and in a decrease of the compressibility modulus of the monolayers. For mixed monolayers at higher content of calix[4]resorcinarene (> 0.2 molar fraction) a deviation from ideal miscibility took place especially for monolayers in a solid state. This can be connected with formation of aggregates of calix[4] resorcinarene. Lowest miscibility and weakest interaction of dopamine with a monolayer was observed for calix[4]resorcinarene molar fraction of 0.33 in the monolayer.