Controlling cell growth on titanium by surface functionalization of heptylamine using a novel combined plasma polymerization mode

The Cell Adhesion and Proliferation Enhancement Impact of Low-Temperature Atmospheric Pressure Plasma-Polymerized Heptylamine on the Surface of Ti6Al4V Alloy

To chemically functionalize the Ti6Al4V alloy surface, a custom-made low-temperature atmospheric pressure plasma reactor device was used to polymerize heptylamine on it. The effect of different deposition times, an important process parameter, was also investigated. For each deposition time group, the surface morphology was observed via scanning electron microscopy (SEM). The surface chemical content was analyzed via X-ray photoelectron spectroscopy, and surface hydrophilicity was measured via water contact angle. The adhesion of bone marrow stromal cells (BMSCs) on the modified Ti6Al4V alloy surfaces was also observed via SEM. A quantitative evaluation of cell proliferation was performed via the Cell Counting Kit-8 assay. The results revealed that amino groups were introduced on the Ti6Al4V alloy surface via plasma-polymerized heptylamine (PPHA). The percentages of NH2/C for various deposition times (0 s, 30 s, 45 s, 60 s, 90 s, and 120 s) were 3.39%, 5.14%, 6.71%, 6.72%, 7.31%, and 7.65%. A 30 s, 45 s, and 60 s deposition time could significantly increase surface hydrophilicity with a mean water contact angle of 62.1 ± 1.6°, 65.7 ± 1.1°, and 88.2 ± 1.4°, respectively. Meanwhile, a 60 s, 90 s, and 120 s deposition time promoted BMSCs cell adhesion and proliferation. However, this promotion effect differed non-significantly among the three groups. In conclusion, the introduction of amino groups on the Ti6Al4V alloy surface exhibited surface modification and enhancement of cell adhesion and proliferation, which was partially associated with deposition time.

Osseointegration behavior of carbon fiber reinforced polyetheretherketone composites modified with amino groups: An in vivo study

Polyetheretherketone (PEEK) has become increasingly popular in dentistry and orthopedics due to its excellent chemical stability, reliable biosafety, and low elastic modulus. However, PEEK's biomechanical strength and bioactivity are limited and need to be increased as an implant material. The previous study in vitro has shown that the amino-functionalized carbon fiber reinforced PEEK (A-30%-CPEEK) possessed enhanced mechanical property and bioactivity. This study aims to evaluate the effect of amino groups modification on the osseointegration behavior of carbon fiber reinforced PEEK (30%-CPEEK) in rabbits. Herein, 30%-CPEEK and A-30%-CPEEK implant discs were implanted in rabbit skulls for 5 weeks, with pure titanium implants serving as a control. The bone-forming ability and osseointegration in vivo were systematically investigated by micro-computed tomography analysis, scanning electron microscope observation, and histological evaluation. Our results showed that all detection parameters were significantly different between the A-30%-CPEEK and 30%-CPEEK groups, favoring those in the A-30%-CPEEK, whose appraisal parameters were equal to or better than pure titanium. Therefore, this study supported the importance of amino groups in facilitating the new bone formation and bone-implant integration, suggesting that A-30%-CPEEK with enhanced osseointegration will be a promising material for dental or orthopedic implants.

Amine-Rich Coatings to Potentially Promote Cell Adhesion, Proliferation and Differentiation, and Reduce Microbial Colonization: Strategies for Generation and Characterization

Biomaterial surface modification represents an important approach to obtain a better integration of the material in surrounding tissues. Different techniques are focused on improving cell support as well as avoiding efficiently the development of infections, such as by modifying the biomaterial surface with amine groups (–NH2). Previous studies showed that –NH2 groups could promote cell adhesion and proliferation. Moreover, these chemical functionalities may be used to facilitate the attachment of molecules such as proteins or to endow antimicrobial properties. This mini-review gives an overview of different techniques which have been used to obtain amine-rich coatings such as plasma methods and adsorption of biomolecules. In fact, different plasma treatment methods are commonly used with ammonia gas or by polymerization of precursors such as allylamine, as well as coatings of proteins (for example, collagen) or polymers containing –NH2 groups (for example, polyethyleneimine). Moreover, this mini-review will present the methods used to characterize such coatings and, in particular, quantify the –NH2 groups present on the surface by using dyes or chemical derivatization methods.

The osteogenesis performance of titanium modified via plasma-enhanced chemical vapor deposition: in vitro and in vivo studies

Titanium (Ti) and its alloys are widely used in dental implants due to their favorable mechanical properties and biocompatibility. Surface characteristics, including physical and chemical properties, are crucial factors to enhance the osteogenesis performance of Ti. The aim of this study is to evaluate amino group surface modification to facilitate the osteogenic potential and bone repair of dental implants both in vitro and in vivo. Herein, amino group-modified Ti surfaces were constructed via the plasma-enhanced chemical vapor deposition (PECVD) technique with an allylamine monomer. The adhesion, proliferation, alkaline phosphate activity and osteogenesis-related genetic expression of MG-63 cells on the surfaces were performed in vitro and presented a significant increase in amino group-modified Ti compared with that in Ti. The in vivo study in miniature pigs was evaluated through micro-computed tomography analysis and histological evaluation, which exhibited enhanced new bone formation in amino group-modified Ti compared with that in Ti after implantation for 4, 8 and 12 weeks. Consequently, amino group surface modification with the PECVD technique may provide a promising modification method to enhance the osteogenesis performance of Ti implants.

Enhanced bioactivity and osteogenic property of carbon fiber reinforced polyetheretherketone composites modified with amino groups

Polyetheretherketone (PEEK) is considered as a potential dental and orthopedic implant material owing to its favorable thermal and chemical stability, biocompatibility and mechanical properties. However, the inherent bio-inert and inferior osseointegration of PEEK have hampered its clinical application. In addition, carbon fiber is widely used as a filler to reinforce polymers for sturdy composites owing to its high strength, modulus, etc. In the study, carbon fiber reinforced PEEK (CPEEK) composites were fabricated and modified with amino groups by plasma-enhanced chemical vapor deposition surface modification technique. The surface characterization of composites was evaluated by FE-SEM, EDS, AFM, Water contact angle, XPS and FTIR, which revealed that amino groups were successfully incorporated on the modified CPEEK surface and significantly increased the hydrophilicity. In vitro study, cell adhesion, proliferation, ALP activity, ECM mineralization, real-time PCR analysis, and ELISA analysis showed the adhesion, proliferation and osteogenic differentiation of MG-63 cells on the amino group-modified CPEEK surface were higher than the CPEEK, equal to or better than pure titanium. Hence, the results indicated that the amino group-modified CPEEK possessed enhanced bioactivity and osteogenic property, which may be a potential candidate material for dental implants.

Plasma Surface Polymerized and Biomarker Conjugated Boron Nitride Nanoparticles for Cancer-Specific Therapy: Experimental and Theoretical Study

A new low-pressure plasma-based approach to activate the surface of BN nanoparticles (BNNPs) in order to facilitate the attachment of folate acid (FA) molecules for cancer-specific therapy is described. Plasma treatment of BNNPs (BNNPs^PT) was performed in a radiofrequency plasma reactor using ethylene and carbon dioxide monomers. The carboxyl groups deposited on the surface of BNNPs^PT were activated by N,N'-dicyclohexylcarbodiimide (DCC) and participated in the condensation reaction with ethylene diamine (EDA) to form a thin amino-containing layer (EDA-BNNP^PT). Then, the DCC-activated FA was covalently bonded with BNNPs^PT by a chemical reaction between amino groups of EDA-BNNPs^PT and carboxyl groups of FA. Density functional theory calculations showed that the pre-activation of FA by DCC is required for grafting of the FA to the EDA-BNNPs^PT. It was also demonstrated that after FA immobilization, the electronic characteristics of the pteridine ring remain unchanged, indicating that the targeting properties of the FA/EDA-BNNPs^PT nanohybrids are preserved.

The effect of amino plasma-enhanced chemical vapor deposition-treated titanium surface on Schwann cells

The surface modification of titanium and its alloys with amino group plasma-enhanced chemical vapor deposition has been proven to enhance the performance of implants on initial osteoblast bioactivity in vitro. However, scarce information on the effect of this kind of surface modification on nerve regeneration exists. In this study, the surface chemistry of pure Ti disks and surface-modified disks was examined using X-ray photoelectron spectroscopy. Cell counting kit 8 assay, 4,6-diamidino-2-phenylindole staining, flow cytometry, and scanning electron microscopy showed that either the p30% or cw + p30% mode-mediated surface significantly promote Schwann cell adhesion without any cytotoxicity compared with the pure Ti surface, and the cw + p30% group showed the best performance on cell adhesion. However, results of polymerase chain reaction and Western blot analyses showed that the mRNA and protein levels of glial cell-derived neurotrophic factor and nerve growth factor of the p30% and cw + p30% groups were lower than those of the Ti group at some time points. Generally, the results indicate that amino-functionalized Ti surfaces can promote Schwann cell adhesion without cytotoxicity, but this modification, in fact, inhibited the expression of the key growth factors GDNF and NGF of Schwann cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 265-271, 2018.

Protective effects of orange (Citrus sinensis L.) peel aqueous extract and hesperidin on oxidative stress and peptic ulcer induced by alcohol in rat

BACKGROUND

Massive alcohol drinking can lead to gastric ulcer. In the present study we investigated the gastroprotective effect of Citrus sinensis peel aqueous extract (CSPE) and Hesperidin (H) in ethanol (EtOH) induced oxidative stress and peptic ulcer in rats.

METHODS

Seventy adult male Wistar rats were divided into seven groups of 10 each: control, EtOH (4 g/kg b.w.), EtOH + various doses of CSPE (100, 200 and 400 mg/kg, b.w.), EtOH + Hesperidin (50 mg/kg, p.o.) and EtOH + Omeprazole (OM, 20 mg/kg, p.o.). Animals were perorally (p.o.) pre-treated with CSPE during 15 days and intoxicated with a single oral administration of EtOH (4 g/kg b.w.) during 2 h. Gastric ulcer was induced in rats with a single dose of ethanol (EtOH). Ulcer index, gene expression of gastric cyclooxygenase-2 (COX-2), tumor necrosis factor alpha (TNF-α), malondialdhyde (MDA), hydrogen peroxide H2O2 and Thiol groups (-SH) content in stomach and antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and gluthation peroxidise (GPx) were measured. Furthermore, histopathological examinations were performed.

RESULTS

The results showed that ethanol induced gastric damage, improving oxidative stress markers level such as MDA (121 ± 4.45 nmol/mg proteins) and H2O2 (24.62 ± 1.04 μmol/mg proteins), increased pro-inflammatory cytokine (TNF-α level), as well as the expression of COX-2 in the ethanol group. However, a significant depletion of enzymatic and non-enzymatic antioxidants were observed, such as, GPx (72%), SOD (57.5%), CAT (41.6%) and -SH (50%). The lesions were associated with severe histopathological damage. The both Citrus sinensis peel aqueous extract (CSPE) and hesperidin significantly protect against all gastric damages caused by ethanol administration in rats.

CONCLUSIONS

We propose that CSPE and hesperidin exhibit protective effects in EtOH-induced peptic ulcer in rat. This protection might be related in to part its antioxidant properties as well as its opposite effects on some studied intracellular mediators.

Plasma Surface Modification of Polyhedral Oligomeric Silsequioxane-Poly(carbonate-urea) Urethane with Allylamine Enhances the Response and Osteogenic Differentiation of Adipose-Derived Stem Cells

This study present amino functionalization of biocompatible polymer polyhedral oligomeric silsequioxane-poly(carbonate-urea) urethane (POSS-PCU) using plasma polymerization process to induce osteogenic differentiation of adipose derived stem cells (ADSCs). Optimization of plasma polymerization process was carried out keeping cell culture application in mind. Thus, samples were rigorously tested for retention of amino groups under both dry and wet conditions. Physio-chemical characterization was carried out using ninhydrin test, X-ray photon spectroscopy, scanning electron microscopy, and static water contact analysis. Results from physio chemical characterization shows that functionalization of the amino group is not stable under wet conditions and optimization of plasma process is required for stable bonding of amino groups to the POSS-PCU polymer. Optimized samples were later tested in vitro in short and long-term culture to study differentiation of ADSCs on amino modified samples. Short-term cell culture shows that initial cell attachment was significantly (p < 0.001) improved on amine modified samples (NH2-POSS-PCU) compared to unmodified POSS-PCU. NH2-POSS-PCU samples also facilitates osteogenic differentiation of ADSCs as confirmed by immunological staining of cells for extracellular markers such as collagen Type I and osteopontin. Quantification of total collagen and ALP activity also shows significant (p < 0.001) increase on NH2-POSS-PCU samples compared to unmodified POSS-PCU. A pilot study also confirms that these optimized amino modified POSS-PCU samples can further be functionalized using bone inducing peptide such as KRSR using conventional wet chemistry. This further provides an opportunity for biofunctionalization of the polymer for various tissue specific applications.

Aging effects of plasma polymerized ethylenediamine (PPEDA) thin films on cell-adhesive implant coatings

Thin plasma polymer films from ethylenediamine were deposited on planar substrates placed on the powered electrode of a low pressure capacitively coupled 13.56 MHz discharge. The chemical composition of the plasma polymer films was analyzed by Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) as well as by X-ray photoelectron spectroscopy (XPS) after derivatization of the primary amino groups. The PPEDA films undergo an alteration during the storage in ambient air, particularly, due to reactions with oxygen. The molecular changes in PPEDA films were studied over a long-time period of 360 days. Simultaneously, the adhesion of human osteoblast-like cells MG-63 (ATCC) was investigated on PPEDA coated corundum blasted titanium alloy (Ti-6Al-4V), which is applied as implant material in orthopedic surgery. The cell adhesion was determined by flow cytometry and the cell shape was analyzed by scanning electron microscopy. Compared to uncoated reference samples a significantly enhanced cell adhesion and proliferation were measured for PPEDA coated samples, which have been maintained after long-time storage in ambient air and additional sterilization by γ-irradiation.