Long-term antifouling surfaces for urinary catheters.

The presence of a variety of bacteria is an inevitable/indispensable part of human life. In particular, for patients, the existence and spreading of bacteria lead to prolonged treatment period with many more complications. The widespread use of urinary catheters is one of the main causes for the prevalence of infections. The necessity of long-term use of indwelling catheters is unavoidable in terms of the development of bacteriuria and blockage. As is known, since a permanent solution to this problem has not yet been found, research and development activities continue actively. Herein, polyethylene glycol (PEG)-like thin films were synthesized by a custom designed plasma enhanced chemical vapor deposition (PE-CVD) method and the long-term effect of antifouling properties of PEG-like coated catheters was investigated against Escherichia coli and Proteus mirabilis. The contact angle measurements have revealed the increase of wettability with the increase of plasma exposure time. The antifouling activity of surface-coated catheters was analyzed against the Gram-negative/positive bacteria over a long-term period (up to 30 days). The results revealed that PE-CVD coated PEG-like thin films are highly capable of eliminating bacterial attachment on surfaces with relatively reduced protein attachment without having any toxic effect. Previous statements were supported with SEM, XPS, FTIR spectroscopy, and contact angle analysis.

Stimuli-responsive nanoparticle-nanofiber hybrids for drug delivery and photodynamic therapy.

Hybrid nanomaterials possess integrated multi-components to syncretize various properties and functions within a single entity. Owing to this synergistic effect, they promise efficient anti-cancer therapy. In line with this target, we produced stimuli-responsive nanoparticle-nanofiber hybrids (NNHs) via embedding photoresponsive natural melanin nanoparticles (MNPs) within a biocompatible polycaprolactone (PCL) nanofiber matrix. Electrospinning was performed to produce monolithic and core-shell structured NNHs using a single and a coaxial nozzle. The NNHs were upgraded to drug delivery systems by model hydrophilic drug-ampicillin (amp)-loading. The drug release results showed that monolithic PCL meshes displayed a burst release, whereas nanohybrid formation with MNPs improved the release profile toward Fickian diffusion. Core-shell NNH presented a more sustained drug release profile than its MNP-free replica and monolithic NNH because its encapsulating shell layer hindered the diffusion of the drug. The photodynamic therapy accompanied by UV-A-irradiation on monolithic and core-shell NNHs yielded up to 34 % and 37 % malignant melanoma cell death. Moreover, this study proved the potency of MNPs-enhanced NNHs in drug delivery and photodynamic therapy applications. Even so, more efforts should be concerted to unlock unknown features of the NNHs, which have the power to advance emerging areas, including but not limited to material science, biosensing, and theranostics.

Controlled drug release performance of plasma modified slab and mat matrices: A model study with "Ampicillin".

Two types of ampicillin carrier platforms were prepared with polycaprolactone (PCL) and the release behavior of a hydrophilic model drug (ampicillin sodium salt) from those matrices was investigated. Spin coating and electrospinning techniques were used to prepare slab and mat platforms, respectively. Ampicillin sodium salt (ASS) at 5% (w:w) concentration was loaded into the slab or mat structures of PCL. The thickness of the slab was measured 3.349 ± 0.345 µm and surface morphology of the slabs showed uniform PCL spherulites. On the other hand, fiber diameter of PCL and ASS loaded PCL (ASSLPCL) was measured 604 ± 176 nm and 549 ± 119 nm, respectively. The dynamic behavior of the controlled release was improved by a very thin film (<100 nm) formation of sulfur hexafluoride (SF6) over the surface via plasma polymerization. Plasma coating was facilitated and speed up the drug diffusion, then led to 45.60 ± 6.46% and 63.67 ± 4.33% enhancement of drug from slab and mat, respectively. Transport mechanism from all matrices showed a Fickian diffusion behavior and plasma modification of the surface did not affected the mechanism. The in vitro antibacterial property of ASS loaded matrices against S. aureus and E. coli was studied through the comparison of bacterial inhibition zones and ASS showed antibacterial effect after all processes.

A comparative study of single-needle and coaxial electrospun amyloid-like protein nanofibers to investigate hydrophilic drug release behavior.

In this study, nanofibers containing an amyloid-like bovine serum albumin (AL-BSA) carrier and a model drug (ampicillin) were produced by electrospinning. The release behavior of ampicillin was compared from electrospun nanofibers prepared as either coaxial or single-needle types. SEM images showed that the membranes had a uniform and smooth structure and the core/shell fibers were found to be thicker than the core fibers. Core/shell production was proved by transmission electron microscopy images. Fourier transform infrared spectroscopy indicated the existence of compatibility between ampicillin and the AL-BSA matrix. The in vitro antimicrobial properties of ampicillin were studied through the comparison of bacterial inhibition zones and ampicillin was found to be more effective against Gram-positive Staphylococcus aureus than Gram-negative Escherichia coli. Moreover, in vitro drug release tests were conducted to explore the relationship between the shell thickness and the drug release rate. A burst release was observed for all membranes owing to the small fiber diameters and thus short diffusion lengths. For core membranes, the drug release mechanism followed Fickian transport, which was close to zero-order kinetic. A typical biphasic release mechanism was observed for the core/shell nanofibers. Overall, we present the first evidence of AL-BSA as a potential core/shell drug mediator.

Controlled release of a hydrophilic drug from electrospun amyloid-like protein blend nanofibers.

In this study, a controlled drug release platform, amyloid-like bovine serum albumin (AL-BSA) with ampicillin sodium salt (amp), was developed. To develop this platform, 5%, 10%, and 20% (w/w) ratios of amp:BSA were used with electrospinning to prepare nanofibers with average diameters of 132±69, 159±60, and 179±42nm, respectively. Fourier transform infrared spectroscopy demonstrated that AL-BSA could entrap large amounts of drug inside the nanofibers, which was attributed to the antimicrobial activity of the released drug against Escherichia coli and Staphylococcus aureus. The amount of drug released was measured by UV-VIS spectrophotometry. The nanofibrous matrix of the electrospun membrane showed controlled release behavior in all samples. The transport mechanism was Fickian for the low ratio of amp:BSA (5% w:w). When the drug ratio was increased to >10% (w:w), thicker fiber structures formed, suggesting that the drug traveled a longer distance to reach the fiber surface; thus, the mechanism of transport shifted from Fickian to non-Fickian.