Solvent Free Fabrication of Micro and Nanostructured Drug Coatings by Thermal Evaporation for Controlled Release and Increased Effects

Abstract

Nanostructuring of drug delivery systems offers many promising applications like precise control of dissolution and release kinetics, enhanced activities, flexibility in terms of surface coatings, integration into implants, designing the appropriate scaffolds or even integrating into microelectronic chips etc. for different desired applications. In general such kind of structuring is difficult due to unintentional mixing of chemical solvents used during drug formulations. We demonstrate here the successful solvent-free fabrication of micro-nanostructured pharmaceutical molecules by simple thermal evaporation (TE). The evaporation of drug molecules and their emission to a specific surface under vacuum led to controlled assembling of the molecules from vapour phase to solid phase. The most important aspects of thermal evaporation technique are: solvent-free, precise control of size, possibility of fabricating multilayer/hybrid, and free choice of substrates. This could be shown for twenty eight pharmaceutical substances of different chemical structures which were evaporated on surfaces of titanium and glass discs. Structural investigations of different TE fabricated drugs were performed by atomic force microscopy, scanning electron microscopy and Raman spectroscopy which revealed that these drug substances preserve their structurality after evaporation. Titanium discs coated with antimicrobial substances by thermal evaporation were subjected to tests for antibacterial or antifungal activities, respectively. A significant increase in their antimicrobial activity was observed in zones of inhibition tests compared to controls of the diluted substances on the discs made of paper for filtration. With thermal evaporation, we have successfully synthesized solvent-free nanostructured drug delivery systems in form of multilayer structures and in hybrid drug complexes respectively. Analyses of these substances consolidated that thermal evaporation opens up the possibility to convert dissoluble drug substances into the active forms by their transfer onto a specific surface without the need of their prior dissolution.

Preparation and Evaluation of Solid Dispersions of A New Antitumor Compound Based on Early-Stage Preparation Discovery Concept

“…The results indicated that formulation as a solid dispersion can enhance the solubility of hydrophobic drug, and more importantly, it can also improve the bioavailability. There are still many approaches which can be introduced into EPDC to improve a new compound's bioavailability, such as solid lipid nanoparticles (24,25), microemulsions, micropowders (26), micro drug coatings (27), liposomes (28), and engineered nanomaterials (29). During early-stage drug discovery research, EPDC cannot only save time but also simplify the process and increase efficiency.…”

Enantiomer-Selective Molecular Sensing Using Racemic Nanoplasmonic Arrays

“…MTE is very suitable for our purpose, since it allows accurate control of the molecular deposit conditions and thickness of the coatings, providing more reproducible, homogeneous and dense molecular layers using a solvent-free method. 45,46 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 gold coated borosilicate substrates separated by a thin (~2 nm) Ti adhesion layer. After exposure and development, the gold layer was exposed to reactive ion etching (Oxford Plasmalab System 100) followed by resist removal in piranha solution (Caution: piranha solution is a very reactive solution and should be handled with the maximum safety precaution).…”

Biomechanical and antibacterial properties of Tobramycin loaded hydroxyapatite coated fixation pins

“…The antibacterial efficacy of Tobramycin incorporated into HA‐B_37 (5 µm) coated pins was evaluated by a modified agar diffusion test in accordance to Zarie et al and the European Pharmacopoeia . Drug loading was performed as described above.…”