ABSTRACT
By altering the surface properties of polytetrafluoroethylene (PTFE) substrates using a special PIII technique, mesenchymal stem cells (MSCs) proliferation and osteogenesis can be promoted in culture without osteogenic supplements. The structures are created intrinsically in the PTFE for no risk of materials delamination. Large-scale features and locally different functions can also be readily produced on the same substrate by this technique.
Subject(s)
Mesenchymal Stem Cells/cytology , Polytetrafluoroethylene/chemistry , Cell Differentiation , Cell Proliferation , Humans , Nanotubes/chemistry , Osteogenesis , Surface PropertiesABSTRACT
Poly aryl-ether-ether-ketone (PEEK) is an alternative to metal alloys in orthopedic applications. Although the polymer provides many significant advantages such as excellent mechanical properties and non-toxicity, it suffers from insufficient elasticity and biocompatibility. Since the elastic modulus of diamond-like carbon (DLC) is closer to that of cortical bone than PEEK, the DLC/PEEK combination is expected to enhance the stability and surface properties of PEEK in bone replacements. In this work, PEEK is coated with diamond-like carbon (DLC) by plasma immersion ion implantation and deposition (PIII&D) to enhance the surface properties. X-ray photoelectron spectrometry (XPS), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy demonstrate successful deposition of the DLC film on PEEK without an obvious interface due to energetic ion bombardment. Atomic force microscopy (AFM) and contact angle measurements indicate changes in the surface roughness and hydrophilicity, and nanoindentation measurements reveal improved surface hardness on the DLC/PEEK. Cell viability assay, scanning electron microscopy (SEM), and real-time PCR analysis show that osteoblast attachment, proliferation, and differentiation are better on DLC/PEEK than PEEK. DLC/PEEK produced by PIII&D combines the advantages of DLC and PEEK and is more suitable for bone or cartilage replacements.
Subject(s)
Biocompatible Materials/chemistry , Carbon/chemistry , Diamond/chemistry , Ketones/chemistry , Polyethylene Glycols/chemistry , Animals , Benzophenones , Cell Adhesion , Cell Line , Cell Proliferation , Cell Survival , Elastic Modulus , Humans , Osteoblasts/cytology , Polymers , Rats , Surface PropertiesABSTRACT
Polytetrafluoroethylene (PTFE) is a commonly used medical polymer due to its biological stability and other attractive properties such as high hardness and wear resistance. However, the low surface energy and lack of functional groups to interact with the cellular environment have severely limited its applications in bone or cartilage replacements. Plasma immersion ion implantation (PIII) is a proven effective surface modification technique. However, when conducted on polymeric substrates, conventional PIII experiments typically employ a low pulsing frequency and short pulse duration in order to avoid sample overheating, charging, and plasma sheath extension. In this paper, a long pulse, high frequency O(2) PIII process is described to modify PTFE substrates by implementing a shielded grid in the PIII equipment without these aforementioned adverse effects. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements are carried out to reveal the surface effects of PTFE after long pulse, high frequency O(2) PIII and the results are compared to those obtained from conventional short pulse, low frequency O(2) PIII, O(2) plasma immersion, and the untreated control samples. Our results show that less oxygen-containing, rougher, and more hydrophobic surfaces are produced on PTFE after long pulse, high frequency O(2) PIII compared to the other 2 treatments. Cell viability assay, ALP activity test, and real-time PCR analysis are also performed to investigate the osteoblast behavior. It is clear that all 3 surface modification techniques promote osteoblast adhesion and proliferation on the PTFE substrates. Improvements on the ALP, OPN, and ON expression of the seeded osteoblasts are also obvious. However, among these treatments, only long pulse, high frequency O(2) PIII can promote the OCN expression of osteoblasts when the incubation time is 12 days. Our data unequivocally disclose that the long pulse, high frequency O(2) PIII technique is better than the other two types of traditional plasma treatment in the development of PTFE for bone or cartilage repair.
Subject(s)
Electrochemical Techniques , Ions/chemistry , Osteoblasts/physiology , Oxygen/chemistry , Polytetrafluoroethylene/chemistry , Alkaline Phosphatase/metabolism , Animals , Biocompatible Materials/chemistry , Biocompatible Materials/metabolism , Cell Adhesion/physiology , Humans , Materials Testing , Microscopy, Atomic Force , Osteoblasts/cytology , Photoelectron Spectroscopy , Polytetrafluoroethylene/metabolism , Rats , Rats, Sprague-Dawley , Surface Properties , X-RaysABSTRACT
We evaluate the effect on testicular histology when fine suture materials are used for transparenchymal suture fixation of the testis during orchiopexy in immature Sprague-Dawley rats. Significant inflammatory reactions were observed in all groups of animals with suture fixation regardless of suture size and material. Only 5% of the animals in the dartos pouch control group had an inflammatory response and no inflammation was noted in the nonoperative controls. Although these findings have not been documented in humans, this evidence raises concerns about the impact of surgical technique on the future reproductive capabilities of these testes. Alternatives to transparenchymal suture fixation of the testis should be considered in patients with cryptorchidism and testicular torsion. Sutureless dartos pouch placement may provide adequate fixation during most orchiopexies without risking injury to testicular structure and function.
