Plasma‐Assisted Surface Modification and Heparin Immobilization: Dual‐Functionalized Blood‐Contacting Biomaterials with Improved Hemocompatibility and Antibacterial Features

The inferior hemocompatibility or antibacterial properties of blood-contacting materials and devices are restraining factors that hinder their successful clinical utilization. To highlight these, a plasma-enhanced modification strategy is favored for surface tailoring of an extensively used biomaterial, polypropylene (PP). The surface activation of the PPs is achieved by oxygen plasma etching and subsequent surface functionalization through amine-rich precursor mediated coating by plasma glow discharge. After optimum plasma processing parameters are decided, heparin (anticoagulant and antithrombic drug) is either attached or covalently conjugated on the PPs’ surfaces. The aminated films produced at 75 W plasma power with 15 min exposure time are highly hydrophilic (34.72 ± 5.92°) and surface active (65.91 mJ m$^{-2}$), facilitating high capacity heparin immobilization (≈440 µg cm$^{-2}$) by covalent linkage. The kinetic-blood coagulation rate and protein adhesion amount on the plasma-mediated heparinized PPs are decreased about tenfold and 15-fold, and platelet adhesion is markedly lowered. In addition, heparinized-PP surfaces comprise superior antibacterial activity against gram-positive/-negative bacteria conveyed particularly by contact-killing (99%). The heparin-coating did not cause cytotoxicity on fibroblast cells, instead enhanced their proliferation, as shown by the (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. Overall, this simple methodology is highly proficient in becoming a universal strategy for developing dual-functionalized blood-contacting materials

Stability enhancement of amine-rich thin films by plasma polymerized n-hexane pre-coating for biomedical applications

Amin gruplarınca zengin ince filmler, biyomoleküllere bağlanma potansiyelleri sebebiyle son yıllarda dikkat çeken konu başlıkları arasında yer almaktadır. Ancak, filmlerin sergiledikleri kararlılık karakteristikleri, biyoteknoloji alanında kullanımlarını kısıtlamaktadır. Bu tez çalışmasında, n-hekzan ön kaplamasının, amin gruplarınca zengin ince filmlerin atmosfer ve sıvı ortamlarda sergiledikleri kararlılık karakteristiğine etkisi araştırılmıştır. Etilendiamin (EDA) filmleri, radyo frekans- düşük basınç (RF-DB) plazma polimerizasyon cihazı kullanılarak, modifiye edilmemiş ve n-hekzan ön kaplaması gerçekleştirilmiş olmak üzere iki farklı gruba ayrılan cam ve kuvars ayar çatalı (QTF) yüzeylerde oluşturulmuştur. N-hekzan ön kaplamasının etilendiamin ince film yapısına etkileri, yüzeydeki fonksiyonel grupları araştırmak adına FTIR-ATR, yüzey kimyasal kompozisyonu araştırılmak üzere XPS, atmosfer ortamında kararlılık çalışmaları Temas Açısı (CA) ve sıvı ortamda kararlılık çalışmaları frekans ölçüm teknikleri ile gerçekleştirilmiştir. Plazma parametreleri her bir karakterizasyon ölçümü göz önüne alınarak ve farklı ortamlarda sergiledikleri kararlılık karakteristikleri incelenerek optimize edilmiştir. Yıpranma hızı çalışmalarının sonuçlarına göre, 75 Watt değerinin aşağısında ve üzerinde boşalım gücü uygulanan n-hekzan ön kaplamasına sahip etilendiamin ince filmler atmosfer ve sıvı ortamlarında kararlı değilken, 75 Watt boşalım gücü değerine sahip ince filmler her iki ortamda da kararlı bir karakteristik sergilemişlerdir. Etilendiamin ince filmlerinden alınan FTIR-ATR ölçümlerinde, 75 Watt değerinin aşağısında ve üzerinde boşalım gücüne sahip ince film yüzeylerinde amin grupları gözlemlenmemiştir. Dolayısıyla FTIR-ATR ölçümleri uyarınca, etilendiamin ince film parametresi 75 Watt 5 dakika şeklinde optimize edilmiştir. Çalışma sonucuna ulaşan en iyi örnekler, n-hekzan ön kaplamalı ve ön kaplamasız etilendiamin ince filmler olmuştur. Söz konusu ince filmler üzerinde atmosfer ve sıvı ortamda kararlılık çalışmaları gerçekleştirilmiştir. Bu çalışmalar göstermiştir ki; n-hekzan ön kaplaması ile etilendiamin kaplaması arasında güçlü bir bağ oluşmuş ve farklı ortamlarda yüzey kararlılığı sağlanmıştır. Sonuç olarak; n-hekzan ön kaplaması ile gerçekleştirilen plazma polimerizayson tekniği ile üretilen ince filmlerde, atmosfer ve sıvı ortamında kararlı yapı elde edilmiş ve yıpranma hızı azaltılarak biyoteknoloji uygulamalarına uygun yüzeyler elde edilmiştir.Amine-rich thin films have a great potential to bind biomolecules for different applications in biotechnology thus, has attracted great attention over the last decades. However, the stability of those films are still challenging which limits their usage in biotechnological applications. Here we investigate the influence of n-hexane (HEX) pre-coating on the stability of amine-rich thin film in air and liquid. Ethylenediamine (EDA) films were deposited on unmodified and n-hexane pre-coated glass and qurtz tuning fork (QTF) substrates by radio frequency generated low pressure plasma system. The influence of n-hexane prcoating on deposited EDA were studied by Fourier transform infrared spectroscopy (ATR-FTIR) for investigating functional groups, X-ray photoelectron spectroscopy for surface chemical compositions, contact angle measurement for stability in gas (air) and frequency measurement for stability in liquid phases. Plasma parameters were optimised by considering the most stable thin films in each media after characterization and stability studies. Results from aging studies indicate that HEX pre-coating those produced below and above 75 Watt was not stable in both air and liquid but pre-coating films produced at 75 Watt showed the highest stability. ATR-FTIR spectra which was collected from EDA demonstrated that below and above 75 Watt, amine groups could not be observed on substrate surfaces. Therefore, plasma parameters of the EDA were optimised to 75 Watt 5 minutes on the basis of ATR-FTIR spectra. In conclusion, a strong interaction between the substrate and plasma polymerized thin films was achieved by n-hexane pre-coating which resulted in enhanced film stability and decreased aging of amine-rich film in air and liquid thus can be adapted for various biotechnological applications

Quartz tuning fork as a mass sensitive biosensor platform with a bi-layer film modification via plasma polymerization

Due to the lack of the stability of amine films, a promising transducer, quartz-tuning fork (QTF) prongs were modified by a bi-layer film of plasma-polymerized n-heptane (hep) and then by ethylenediamine (EDA), respectively. For this purpose, the authors investigate the stability of amine-rich thin films both in air and aqueous medium. EDA films were deposited on QTF substrates by using an RF plasma system. The final amine-rich thin film was used to immobilize biologic recognition element. Model protein studies were showed that selected thin films could be adapted to QTF transducers to be used as a biosensor template

Simultaneous insulation and modification of quartz tuning fork surface by single-step plasma polymerization technique with amine-rich precursors

Amine-based plasma polymer thin films (NH2-PPTFs) are favorable due to their potential ability for binding a variety of biomolecules, especially in biotechnologic studies. In this context, to understand the effect of different amine sources on quartz tuning forks' (QTF) surface functionalization and isolation, we prepared PPTFs by single-step plasma polymerization process. The amino-group concentration of PPTF's was proportionally increased by increasing discharge powers, whereas not affected from exposure time. It was observed that the resistivity increased with the increasing molecular weight of the precursor. In conclusion, NH2-PPTF-modified QTFs present as a great candidate for future biotechnologic applications

Prevention of Candida biofilm formation over polystyrene by plasma polymerization technique

Abstract This work investigates the antifungal effect of plasma polymer films produced by low-pressure RF-generated plasma system using acrylic acid, 2-hydroxyethyl methacrylate, and diethyl phosphite (DEP). Unmodified and plasma-modified polystyrene (PS) microplate wells were tested by 30 biofilm-positive Candida spp. isolated from blood samples and two control strains using a quantitative plaque assay method. Regardless of the precursors and plasma parameters, biofilm formation was inhibited for all plasma-modified microplate wells. The most significant anti-biofilm effect was observed on PS modified by DEP at 90 W plasma power with the inhibition of all Candida species' biofilm formation

Natural Melanin Nanoparticle-decorated Screen-printed Carbon Electrode: Performance Test for Amperometric Determination of Hexavalent Chromium as Model Trace

A biosensor was prepared with natural melanin nanoparticles (MNP) decorated on a screen-printed carbon electrode (SPCE). Hexavalent chromium was selected as a well-known heavy metal ion to be detected for testing the performance of novel biosensor. Natural MNP was extracted from cuttlefish (Sepia officinalis) ink. Surface decoration of SPCEs with MNP was performed by two different methods. The first one was layer-by-layer assembly (LBL-A) for different cycle times(n). In the second one, plasma treatment of SPCE incorporated with evaporation-induced self-assembly (EI-SA) techniques including different incubation times in MNP solutions. The performance of both modified SPCEs were tested for amperometric detection of Cr(VI) in various water samples, and peak reduction of Cr(VI) was determined at 0.33 V. Amperometric results showed wide linear ranges of 0.1–2 ?M and 0.1–5 ?M of Cr(VI) for SPCEs modified with 14n-LBL-A and 12h-EI-SA, respectively. The sensitivities of SPCEs modified with 14n-LBL-A and 12h-EI-SA techniques were 0.27 ?A ?M?1 and 0.52 ?A ?M?1, respectively. In addition, both modified SPCEs selectively detected Cr(VI) in a model aqueous system composed of certain other heavy metals and minerals, and tap and lake water samples. The LOD and LOQ values for 12h-EI-SA were 0.03 ?M and 0.1 ?M, respectively. This showed that MNP-modified-SPCEs generated via EI-SA techniques have the potential to be an alternative to conventional detection methods such as ICP-MS

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 ?m 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