Objective: To determine the effects of graphene oxide (GO) deposition (on a zirconia surface) on bacterial adhesion and osteoblast activation. Methods: An atmospheric pressure plasma generator (PGS-300) was used to coat Ar/CH₄ mixed gas onto zirconia specimens (15-mm diameter × 2.5-mm thick disks) at a rate of 10 L/min and 240 V. Zirconia specimens were divided into two groups: uncoated (control; Zr) group and GO-coated (Zr-GO) group. Surface characteristics and element structures of each specimen were evaluated by field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and contact angle. Additionally, crystal violet staining was performed to assess the adhesion of Streptococcus mutans. WST-8 and ALP (Alkaline phosphatase) assays were conducted to evaluate MC3T3-E1 osteoblast adhesion, proliferation, and differentiation. Statistical analysis was calculated by the Mann–Whitney U-test. Results: FE–SEM and Raman spectroscopy demonstrated effective GO deposition on the zirconia surface in Zr-GO. The attachment and biofilm formation of S. mutans was significantly reduced in Zr-GO compared with that of Zr (P < 0.05). While no significant differences in cell attachment of MC3T3-1 were observed, both proliferation and differentiation were increased in Zr-GO as compared with that of Zr (P < 0.05). Significance: GO-coated zirconia inhibited the attachment of S. mutans and stimulated proliferation and differentiation of osteoblasts. Therefore, GO-coated zirconia can prevent peri-implantitis by inhibiting bacterial adhesion. Moreover, its osteogenic ability can increase bone adhesion and success rate of implants.

The vacuum deposition method requires high energy and temperature. Hydrophobic reduced graphene oxide (rGO) can be obtained by plasma-enhanced chemical vapor deposition under atmospheric pressure, which shows the hydrophobic surface property. Further, to compare the effect of hydrophobic and the hydrophilic nature of catalysts in the photoelectrochemical cell (PEC), the prepared rGO was additionally treated with plasma that attaches oxygen functional groups effectively to obtain hydrophilic graphene oxide (GO). The hydrogen evolution reaction (HER) electrocatalytic activity of the hydrophobic rGO and hydrophilic GO deposited on the p-type Si wafer was analyzed. Herein, we have proposed a facile way to directly deposit the surface property engineered GO.

Introduction: This paper presents a novel technique for the synthesis of graphene oxide (GO) with various surface features using high-density atmospheric plasma deposition. Furthermore, to investigate the use of hydrophobic, super-hydrophobic, and hydrophilic graphene in biological applications, we synthesized hydrophobic, super-hydrophobic, and hydrophilic graphene oxides by additional heat treatment and argon plasma treatment, respectively. In contrast to conventional fabrication procedures, reduced graphene oxide (rGO) formed under low pressure and high-temperature environment using a new synthesis method—developed and described in this study—offers a convenient deposition method on any kind surface with controlled wettability. Methods: High density at atmospheric plasma is used for the synthesis of rGO and GO and its biocompatibility based on various wetting properties was evaluated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the viability of cells in response to rGO and GO with various surface features was investigated. Structural integrity was characterized by Raman spectroscopy, FESEM and FE-TEM. Wettability was measured via contact angle method and confirmed with XPS analysis. Results: We found that GO coating with a hydrophilic feature is more biocompatible than other surfaces as observed in case of fibroblast cells. We have shown that wettability—controlled by GO deposition—influences biocompatibilities and antibacterial effect of biomaterial surfaces. Discussion: Measuring the contact angle, it is found that contact angle for hydrophobic is increased to 150.590 and reduced to 11.580 by heat and argon plasma treatment, respectively, from 75.880 that was initially in the case of hydrophobic surface. XPS analysis confirmed various oxygen-containing functional groups transforming as deposited hydrophobic surface into superhydrophobic and hydrophilic surface. Thus, we have proposed a new, direct, cost-effective, and highly productive method for the synthesis of rGO and GO—with various surface properties—for biological applications. Similarly, for the dental implant application, the Streptococcus mutans was used as an antibacterial effect and found that S. mutans grows slowly on hydrophilic surface. Thus, antibacterial effect was prominent on GO with hydrophilic surface.

Introduction: Photodynamic therapy (PDT), which induces tissue damage by exposing tissue to a specific wavelength of light in the presence of a photosensitizer and oxygen, is a promising alternative treatment that could be used as an adjunct to chemotherapy and surgery in oncology. Cell-penetrating peptides (CPPs) with high arginine content, such as protamine, have membrane translocation and lysosome localization activities. They have been used in an extensive range of drug delivery applications. Methods: We conjugated cell-penetrating peptides (CPPs) with methylene blue (MB) and then purification by FPLC. Synthesis structure was characterized by the absorbance spectrum, FPLC, Maldi-TOF, and then evaluated cell viability by cytotoxicity assay after photodynamic therapy (PDT) assay. An uptake imaging assay was used to determine the sites of MB and MB-Pro in subcellular compartments. Results: In vitro assays showed that MB-Pro has more efficient photodynamic activities than MB alone for the colon cancer cells, owing to lysosome rupture causing the rapid necrotic cell death. In this study, we coupled protamine with MB for high efficacy PDT. The conjugates localized in the lysosomes and enhanced the efficiency of PDT by inducing necrotic cell death, whereas PDT with non-coupled MB resulted in only apoptotic processes. Discussion: Our research aimed to enhance PDT by engineering the photosensitizers using CPPs coupled with methylene blue (MB). MB alone permeates through the cell membrane and distributes into the cytoplasm, whereas coupling of MB dye with CPPs localizes the MB through an endocytic mechanism to a specific organelle where the localized conjugates enhance the generation of reactive oxygen species (ROS) and induce cell damage.