Medical Grade Stainless Steel Research Articles

Amorphous TiO2 nano-coating on stainless steel to improve its biological response

This study delves into the potential of amorphous titanium oxide (aTiO2) nano-coating to enhance various critical aspects of non-Ti-based metallic orthopedic implants. These implants, such as medical-grade stainless steel (SS), are widely used for orthopedic devices that demand high strength and durability. The aTiO2 nano-coating, deposited via magnetron sputtering, is a unique attempt to improve the osteogenesis, the inflammatory response, and to reduce bacterial colonization on SS substrates. 
The study characterized the nanocoated surfaces (SS-a TiO2) in topography, roughness, wettability, and chemical composition. Comparative samples included uncoated SS and sandblasted/acid-etched Ti substrates (Ti). The biological effects were assessed using human mesenchymal stem cells (MSCs) and primary murine macrophages. Bacterial tests were carried out with two aerobic pathogens (S. aureus and S. epidermidis) and an anaerobic bacterial consortium representing an oral dental biofilm.
Results from this study provide strong evidence of the positive effects of the aTiO2 nano-coating on SS surfaces. The coating enhanced MSC osteoblastic differentiation and exhibited a response similar to that observed on Ti surfaces. Macrophages cultured on aTiO2 nano-coating and Ti surfaces showed comparable anti-inflammatory phenotypes. Most significantly, a reduction in bacterial colonization across tested species was observed compared to uncoated SS substrates, further supporting the potential of aTiO2 nano-coating in biomedical applications.
The findings underscore the potential of magnetron-sputtering deposition of aTiO2 nano-coating on non-Ti metallic surfaces such as medical-grade SS as a viable strategy to enhance osteoinductive factors and decrease pathogenic bacterial adhesion. This could significantly improve the performance of metallic-based biomedical devices beyond titanium.

Cellulose Acetate and Polycaprolactone Fibre Coatings on Medical-Grade Metal Substrates for Controlled Drug Release.

This study explores a method that has the potential to be cost effective in inhibiting biofilm formation on metallic prostheses, thereby preventing rejection or the requirement for replacement. A cost-effective metal alloy used in biomedical implants was chosen as the substrate, and ibuprofen (Ibu), a well-known anti-inflammatory drug, was selected for drug release tests for its widespread availability and accessibility. Multilayer coatings consisting of cellulose acetate (CA), polycaprolactone (PCL), and chitosan (CHI), with or without ibuprofen (Ibu) content, were applied onto medical-grade stainless steel (SS-316 type) through electrospinning, electrospray, or blow spinning. The adhesion of the CA, PCL, and layered CA/PCL membranes, with thicknesses ranging from 20 to 100 μm, to SS substrates varied between 0.15 N and 0.22 N without CHI, which increased to 0.21 and 0.74 N, respectively, when a CHI interlayer was introduced by electrospraying between the SS and the coatings. Although drug release in a simulated body fluid (SBF) medium is predominantly governed by diffusion-driven mechanisms in all single- and multilayer coatings, a delayed release was noted in CA coatings containing Ibu when overlaid with a PCL coating produced by blow spinning. This suggests avenues for further investigations into combinations of multilayer coatings, both with and without drug-imbued layers.

The influence of low nitrogen doping on bacterial adhesion of sputtered a-C:H coatings

Heavily dependent on both surface and bacteria characteristics, multiple and complex parameters control bacterial adhesion to any biomaterial surface. That's why there are so many contradictory results regarding the antibacterial and adhesion inhibition properties of Diamond-Like Carbon (DLC) protective coatings, despite the well-established biocompatibility of this very broad group of materials. Aiming at Orthodontics, this study reports the modification of hydrogenated amorphous carbon coatings (a-C:H), by nitrogen incorporation upon reactive magnetron sputtering. The effect of low N content up to 10 at.% on the microstructure and bacterial adhesion was studied. Despite the progressive graphitization upon doping, the surface roughness was not significantly influenced and the water contact angles remained above 70°. The adhesion of three bacterial strains of Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa was evaluated. The median colony forming units was lower on the a-C:H and a-C:H:N coatings in comparison to the bare AISI 316L medical grade stainless steel surface, regardless the bacterial strain. The best bacterial adhesion inhibition capacity was achieved for N doping of 6 at.%, without using any antibacterial agents.

Electrophoretic deposition of TiO2 nanotubes and antibiotics on polyurethane coated stainless steel for improved antibacterial response and cell viability

In the quest for advancing the performance of metallic implants, surface modification emerges as a pivotal strategy to mitigate ion depletion, enhance the host's biological response, and exhibit anti-microbial behavior with reduced cytotoxicity. In this study, we developed a non-traditional electrophoretic deposition (EPD) hybrid coating for medical-grade stainless steel 316 L (SS316L) surfaces covered with a segmented polyurethane (SPU). These coatings are composed of anatase TiO2 nanotubes (TiO2_A), and antibiotics (nisin N or gentamicin G). We characterized the modified metals using FTIR and Raman spectroscopy, contact angle measurements, AFM, TGA, SEM-EDX, as well as assessing their antimicrobial response and cell cytotoxicity. The results demonstrate the formation of porous surfaces with embedded nanotubes and antibiotics within and on the polyurethane surfaces. Samples with SPU+ TiO2_AG EPD exhibited superior coverage, antimicrobial properties, and enhanced viability compared to cases where only particles or antibiotics were coated individually. Additionally, samples of SPU+ TiO2_AN EPD displayed favorable hydrophilicity and suitable cytotoxicity. Therefore, the synergistic effect of nanoparticles and antibiotics positively influences the functionality of the coating.

Surface Modifications of Medical Grade Stainless Steel

Medical-grade stainless steel (MSS) is one of the most widely used materials for implantable devices in biomedical applications, including orthopedic stents, dental implants, cardiovascular stents, cranial fixations, and surgical suture materials. Implants are exposed to corrosive body fluids containing chlorides, proteins, and amino acids, resulting in corrosion, wear, toxicity, inflammation, infection, and failure. MSS-based materials exhibit improved corrosion and mechanical resistance and suppress the degradation and release of toxic metal ions. Although MSS is manufactured with a passivating metal oxide layer, its anti-corrosion performance against chlorides and chemicals in body fluids is insufficient. Implants require biocompatibility, bioactivity, hemocompatibility, and sustainability. Antimicrobial activity and sustained drug release are also crucial factors. Therefore, stainless steel with desirable multifunction is in great clinical demand. This comprehensive review summarizes recent advances in the surface modification of MSS-based implants and their biomedical applications, especially in dentistry.

A short review of medical-grade stainless steel: Corrosion resistance and novel techniques

Due to its exceptional quality as a biomedical metal, stainless steel is often utilized to produce a broad range of medical tools. The resistance of stainless steel to corrosion is a key indicator of how long and how effective it will serve its intended purpose, and it is an important factor in determining the biocompatibility of the material. However, due to the complex physiological environment within the human body, the corrosion management of medical-grade stainless steel is facing several challenges. In this article, an overview of the factors that influence the corrosion performance of medical-grade stainless steel is provided, and new technologies and methods that have been developed in recent years to improve the corrosion resistance are discussed. These cutting-edge methods are expected to improve the corrosion resistance and longevity of medical-grade stainless steel, providing strong support for the increased applicability of the material in the medical industry.

Development of occlusal canting identifying tool: verification, reliability and validation assessment

IntroductionOcclusal cant (OC) is a malocclusion trait that lacks accurate clinical assessment methods. The occlusal canting identifying tool (OCIT) was invented and patented as a clinical tool to accurately identify and quantify the degree of maxillary OC. This study aimed to 1) develop a prototype of the OCIT, 2) verify the functionality of the OCIT and 3) assess the validity and reliability of the OCIT.Materials and methodsA patented OCIT design was revised, and the dimensions were finalized, followed by a three-dimensional conceptual prototype design that was reviewed and approved by the inventors. Verification was performed using a digital angle gauge to determine the accuracy of the bubble level as well as the angle between the bite plate and the protractor. For laboratory validation, 40 orthodontists measured the simulated OC at (0°, 2°, 4°, 6° and 8°) on five phantom heads using the OCIT. A reliability assessment of the tool was performed in three occasions by one orthodontist using the same laboratory settings.ResultsThe OCIT was prototyped from a medical-grade stainless steel alloy (316 L). Verification assessment revealed that the accuracy error of the bubble level (0.316° ± 0.028°) was statistically significant but clinically insignificant, while that of the angle between the bite plate and protractor (0.100° ± 0.050°) was statistically insignificant. Validation assessment showed high validity of the OCIT with no statistically significant difference between the OCIT and the reference values, having more errors in identifying smaller OC degrees compared to larger OC degrees. The intraclass correlation coefficient indicated the high reliability of the OCIT.ConclusionThe OCIT was verified and proven to be a valid and reliable clinical tool that accurately evaluates the degree of OC.

Enhancing Antibacterial Performance: Structure, Phase Composition, and Microroughness of Selective Plated Copper Coatings on Medical-Grade Stainless Steel 1.4021 and Nickel Alloy Ni200

This study presents a preliminary characterization of selective plated antibacterial copper coatings on medical-grade stainless steel 1.4021 and nickel alloy Ni200 substrates using two different copper electrolyte solutions with acidic and alkaline pH. The characterizations included analysis of the microstructure, phase composition, surface roughness, and antibacterial activity against Gram-positive Staphylococcus aureus ATCC 29213 and Gram-negative Escherichia coli ATCC 25922 bacteria. The results revealed uniform and continuous layers of single-phase solid-solution copper coatings without any cracks or defects. The coatings, produced using acidic or alkaline solutions, exhibited approximately 20% or 40% lower surface roughness compared to the substrate roughness. This suggests that the plating process led to a smoother surface finish. Importantly, all of the selective plated copper coatings exhibited antibacterial properties. Inhibition zones were identified, indicating the ability of the coatings to inhibit the growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The use of the alkaline copper solution resulted in slightly larger inhibition zones compared to the acidic solution, indicating enhanced antibacterial activity. These findings suggest that the selective plated copper coatings on medical-grade stainless steel 1.4021 and nickel alloy Ni200 substrates have the potential to be effective antibacterial surfaces.

Affinity-based electrochemical biosensor with antifouling properties for detection of lysophosphatidic acid, a promising early-stage ovarian cancer biomarker

Electrochemical techniques are considered to be highly sensitive, capable of fast response and can be easily miniaturized, properties which can aid with regard to the fabrication of compact point-of-care medical devices; however, the main challenge in developing such a tool is overcoming a ubiquitous, problematic phenomenon known as non-specific adsorption (NSA). NSA is due to the fouling of non-target molecules in the blood on the recognition surface of the device. To overcome NSA, we have developed an affinity-based electrochemical biosensor using medical-grade stainless steel electrodes and following a unique and novel strategy using silane-based interfacial chemistry to detect lysophosphatidic acid (LPA), a highly promising biomarker, which was found to be elevated in 90 % of stage I OC patients and gradually increases as the disease progresses to later stages. The biorecognition surface was developed using the affinity-based gelsolin-actin system, which was previously investigated by our group to detect LPA using fluorescence spectroscopy. We demonstrate the capability of this label-free biosensor to detect LPA in goat serum with a detection limit of 0.7 µM as a proof-of-concept for the early diagnosis of ovarian cancer.

Biomimetic calcium phosphate coating on medical grade stainless steel improves surface properties and serves as a drug carrier for orthodontic applications.

Recently, stainless steel (SSL) miniscrew implants have been used in orthodontic clinics as temporary anchorage devices. Although they have excellent physical properties, their biocompatibility is relatively poor. Previously, our group developed a two-phase biomimetic calcium phosphate (BioCaP) coating that can significantly improve the biocompatibility of medical devices. This study aimed to improve the biocompatibility of SSL by coating SSL surface with the BioCaP coating. Titanium (Ti) discs and SSL discs (diameter: 5mm, thickness: 1mm) were used in this study. To form an amorphous layer, the Ti discs were immersed in a biomimetic modified Tyrode solution (BMT) for 24h. The SSL discs were immersed in the same solution for 0h, 12h, 24h, 36h and 48h. To form a crystalline layer, the discs were then immersed in a supersaturated calcium phosphate solution (CPS) for 48h. The surface properties of the BioCaP coatings were analysed. In addition, bovine serum albumin (BSA) was incorporated into the crystalline layer during biomimetic mineralisation as a model protein. The morphology, chemical composition and drug loading capacity of the BioCaP coating on smooth SSL were confirmed. This coating improved roughness and wettability of SSL surface. In vitro, with the extension of BMT coating period, the cell seeding efficiency, cell spreading area and cell proliferation on the BioCaP coating were increased. These in vitro results show that the BioCaP coating can improve surface properties of smooth medical grade SSL and serve as a carrier system for bioactive agents.

Evaluation of 3D printed PEEK and other 3D printed biocompatible materials as healthcare devices

Introduction and Aim: Additive manufacturing has sought a widespread attention and higher rate of development which can also be modeled by processing of the data acquired by medical Computer Tomography scan. The object is built on a built plate of the printer in layers to form a final required model. Thus, a patient-specific model can be created from imaging data set. Materials available for such printing are elastomers, polymers, metals, or ceramics. The polymer, Polyether ether ketone (PEEK) has been used in health care applications, such as medical devices, and implants due to its high strength, biocompatibility, and light weight. Stainless steel (316L) is commonly used due to its strength, bio-tolerance, corrosion resistance and its formability. The aim of this study was to compare the mechanical strength and biocompatibility of medical grade PEEK and stainless steel. Material and Methods: The test sample of PEEK was prepared using unreinforced PEEK (450G-Victrex Plc., Lancashire, UK) at the Prototyping Lab with a 3D-Printer - INTAMSYS - FUNMAT HT. Samples of stainless steel was printed using the iFusion SF1 Metal 3D Printer using Powder Bed Fusion (PBF) technology. The mechanical tests such as compressive, impact, and tensile tests were performed using an electromechanical universal testing machine (UTM) model- Zwick/Roell Z020 with a 20kN load cell. Biocompatibility tests were done using L929 cells to assess the cytotoxicity of the dental materials. Results: The tensile strength of PEEK polymer was 70+1.6 and the impact strength of PEEK polymer was 289 J/m. Conclusion: The tensile strength of stainless steel was higher compared to that of PEEK polymer, and the impact strength of PEEK polymer higher compared to stainless steel. Thus, it can be concluded that both biomaterial such as 316L stainless steel and PEEK are non-toxic to fibroblast.

Amoxicillin doped hyaluronic acid/fucoidan multifunctional coatings for medical grade stainless steel orthopedic implants

This work investigated the potential of amoxicillin-doped hyaluronic acid/fucoidan multifunctional coatings on medical grade stainless steel as biocompatible, osteointegration enhancing, antimicrobial, and bacterial biofilm inhibiting coatings for orthopedic implants. The coatings were prepared by layer-by-layer spin coating and confirmed by optical contact angle goniometry and infrared spectroscopy. Time-of-flight secondary ion mass spectrometry showed a homogeneous distribution of the individual layers. In contrast, thermal diffusivity, and thermal conductivity measurements by photothermal beam deflection spectrometry showed diffusion of the amoxicillin into the hyaluronic acid and fucoidan layers. In vitro release of amoxicillin showed complete release within one hour, as reflected by the formation of inhibition zones against Staphylococcus aureus and Escherichia coli. Synergistic effects were observed between the hyaluronic acid and amoxicillin in inhibiting S.Aureus biofilm, and between the fucoidan and amoxicillin in improving the antioxidant properties by an ABTS radical scavenging assay. Biocompatibility was determined with human osteoblasts, confirming the potential of such multifunctional coatings to enhance the bioactivity of steel-based orthop edic implants.

Non-antibiotic antimicrobial polydopamine surface coating to prevent stable biofilm formation on satellite telemetry tags used in cetacean conservation applications

Satellite telemetry tags, used to monitor the migratory behavior of cetaceans, have the potential to be a vehicle for infection due to their invasive nature. Antibiotic coatings have been previously employed to reduce the chances of infection via the formation of a stable biofilm on the surface of the tags. However, increased use of antibiotics has the potential to lead to the development of antibiotic-resistant pathogens. To prevent the formation of antibiotic-resistant pathogens, a polydopamine surface coating that, when exposed to oxygen, releases low doses (~40-100µM) of hydrogen peroxide over a prolonged period (>24 hours) can be used to replace current antibiotic coatings used in the field. These pDA coatings can reduce bacterial adhesion from model bacteria from the two most common genotypes found on the skin of cetaceans (Psychrobacter and Tenacibaculum). The adhesion of Psychrobacter bacteria was reduced by 80% (p<0.01) while Tenacibaculum was reduced by 70% (p<0.001). When the bacteria were dosed with a non-lethal quantity of hydrogen peroxide (200µM) prior to being exposed to pDA surface coatings, there was no decrease in the efficacy of the coatings. This indicates a resistance to hydrogen peroxide will not be formed quickly. Overall, the polydopamine surface coatings were able to reduce the adhesion of model bacteria strains on the surface of medical grade stainless steel, which could increase the functional tag service life while reducing the chances of infection.

Nanoporous Stainless Steel Materials for Body Implants-Review of Synthesizing Procedures.

Despite the inadequate biocompatibility, medical-grade stainless steel materials have been used as body implants for decades. The desired biological response of surfaces to specific applications in the body is a highly challenging task, and usually not all the requirements of a biomaterial can be achieved. In recent years, nanostructured surfaces have shown intriguing results as cell selectivity can be achieved by specific surface nanofeatures. Nanoporous structures can be fabricated by anodic oxidation, which has been widely studied for titanium and its alloys, while no systematic studies are so far available for stainless steel (SS) materials. This paper reviews the current state of the art in the anodisation of SS; correlations between the parameters of anodic oxidation and the surface morphology are drawn. The results reported by various authors are scattered because of a variety of experimental configurations. A linear correlation between the pores’ diameter anodisation voltage was deduced, while no correlation with other processing parameters was found obvious. The analyses of available data indicated a lack of systematic experiments, which are recommended to understand the kinetics of pore formation and develop techniques for optimal biocompatibility of stainless steel.

Electrodeposition of hydroxyapatite and graphene oxide improves the bioactivity of medical grade stainless steel

The improvement of bioactivity, biocompatibility, and corrosion resistance of metal substrates are the common goals in biomaterials research. Graphene oxide (GO) for its outstanding chemical and mechanical properties has attracted researchers. Relatively, Hydroxyapatite (HA) has been employed as a biocompatible coating material to improve bone fixation property, durability, and osteointegration of an implant. Therefore, in this study, a composite of GO and HA (GO-HA) was coated on medical grade stainless steel (MS 316L) substrate by anodic electrochemical deposition to improve mechanical peeling resistance, corrosion resistance, and bioactivity. The coating's morphology and ability to cover the substrate surface were analyzed by SEM-EDS, XPS, and the surface roughness by AFM. The coating's structural properties were analyzed with Raman spectroscopy. The investigation of corrosion inhibition involved open circuit potential, EIS, and Voltammetry analysis. The standard salt test, an American Society for Testing and Materials (ASTM) G48A for stainless steel substrate, has also been studied. The bioactivity of the coated substrates was investigated in simulated body fluid (SBF). Significant enhancement of corrosion potential as well as bioactivity of the coated substrates has been achieved. GO-HA coating onto MS 316L was strongly adherent, uniform, and able to provide optimum surface roughness. Hence, the combination of the improved surface properties and bioactivity indicates that GO-HA coating can be utilized to overcome apposite limitations of bare MS 316L surface in clinical settings.

Evaluation of corrosion resistant, antimicrobial and cytocompatible behaviour of cobalt based metallosurfactants self-assembled monolayers on 316L stainless steel surface

The present research is aimed at developing a more economic and ecological way to improve the biocompatibility of medical-grade stainless steel. In order to accomplish the purpose, the 316L stainless steel has been functionalized by depositing self-assembled monolayers (SAMs) of cost-effective Cobalt-based metallosurfactants (CoMS). The fabrication of well-defined SAMs on the surfaces was characterised using FTIR-ATR, spectroscopic ellipsometry and water contact angle measurements. The corrosion stability of functionalized surfaces in simulated body fluid was accessed by various electrochemical and spectroscopic techniques like cyclic potentiodynamic polarisation (CPP), chronoamperometry, electrochemical impedance spectroscopy, FE-SEM, XPS and ICP-MS studies. The metallosurfactant SAMs provided superior corrosion and bacterial protection especially against Gram-negative E. coli bacteria. The cytotoxicity of the SAMs against mouse embryonic fibroblast cell line (NIH-3T3) was assessed by MTT and fluorescent assays. The experimental results reveals that the metallosurfactant SAMs are multifunctional i.e., they enhanced the anticorrosive and anti-bacterial properties of the SS 316L without compromising the cytocompatibility of the surface which make them promising candidates for biomedical applications.

Accuracy of magnetic localisation device placement and retrieval in breast cancer patients from a single internationally accredited breast center in Johannesburg, South Africa.

e18697 Background: A variety of techniques are used to localise breast cancers prior to breast surgery. One such technique involves the placement of a magnetic device (Magseed). the magnetic device placement data from one radiology unit in a multi-disciplinary unit consisting of 4 radiology units over a 6 month period which sees 450 newly diagnosed breast cancer patients per year and places with over 360 Magseeds in a 6 month period. The aim of the study was to conduct a review of Magseed placement and ease and efficacy of retrieval across varying depths within the breast. Methods: The device used and analyzed in this study is constructed of medical-grade stainless steel magnetized, 1x5mm in size and can be implanted long term. The seeds were placed both under ultrasound guidance and stereotactically, there were no complications at the time of placement. Post-placement ease of localization and retrieval of the Magseed Measurements of distances from the nearest perpendicular skin surface was provided by the radiologist. markers were assessed by confirmation of the presence of the Magseed(s) in the specimen through the use of the Sentimag probe and confirmation visualized by intraoperative radiology and intra-operative pathology. Results: All of the seeds were localised during surgery and retrieved without difficulties reported by surgeons. The use of intraoperative radiology confirmed retrieval of all seeds in all patients. The minimum placement depth was 8.33mm, the maximum placement depth was 87mm and the average placement depth was 47mm. The placement of the seeds were place over a range of times before surgery, from 3 days prior to surgery to up to 249 days. Localisation was 100% successful using the Sentimag probe in theatre, and the retrieval rate was 100% across the full 368 analyzed patient set. . Radiological confirmation of the Magseed placement was confirmed through the use of an intraoperative radiological Biovision machine. Our data shows that Magseeds can be placed across a wide range of breast sizes and at variable depths with no complications or difficulty experienced during intraoperative localization and retrieval of the seeds. Conclusions: The data collected, and the demographic analyzed, shows that magnetic marker placement and retrieval is possible across a wide range of depths in the breast with no complications arising in radiological placement and intraoperative localisation and retrieval. Surgeons reported ease of transcutaneous localisation. A 100% retrieval rate was reported. In all cases, clear margins were achieved with: aid from audio and visual confirmation from the Sentimag probe; intraoperative radiology and intraoperative pathology.

Anodization of medical grade stainless steel for improved corrosion resistance and nanostructure formation targeting biomedical applications

Stainless steel is extensively used in various biomedical engineering and hospital applications, including surgical equipment and furniture. Strong adhesion of bacteria and viruses on metal surfaces can restrict long-term utilization for biomedical applications. This study aims to develop an improved electrochemical etching protocol for the anodization of 316 L grade stainless steel (10 × 15 mm) to fabricate nanostructures for biomedical and hospital applications. Anodizing conditions were optimized using two different electrolyte solutions; HNO3: H2SO4 (1:1) and HNO3, by varying applied potential, electrolyte concentration and anodizing time. Morphology and topography of the anodized surfaces were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM). AC and DC electrochemical techniques were used to further characterize the corrosion behaviour of the nanostructured surfaces. Electrochemical optimization produced two different nanostructured surfaces with the anodizing conditions of (1) 50% HNO3 at 0.465 A/cm2 for 1 min (surface 1), and (2) 0.5 M HNO3 + H2SO4 (1:1) at 0.366 A/cm2 for 5 min (surface 2). Both processes produced nanoscale surface roughness with varying corrosion susceptibility. Surfaces anodized using 50% HNO3 comprised of ‘hierarchical roughness’ with dense spikes (10 – 20 nm in diameter), covering rock candy-like protrusion (10 - 15 µm diameter). Whereas the second set of conditions produced single scale roughness with a terrace-like topography with nanoscale ridges of 34.8 ± 1.2 nm in width atop microscale hills. Surface 2 possessed improved corrosion resistance through the formation an oxide film, while the surface 1 was more susceptible to corrosion. Overall, this study demonstrates the importance of the careful optimization of electrochemical surface treatment for medical grade stainless steel in terms of roughness of nanostructures and corrosion susceptibility.

Long‐term result of combined ab externo Schlemm’s canal surgery and phacoemulsification in management of open angle glaucoma in cataract patients

AbstractPurposeTo evaluate the effectiveness of segmental Schlemm’s canal (SC) distension using Kumar’s Schlemm’s canal expander (SCE) in decreasing intraocular pressure (IOP) in cataract patients suffering from open angle glaucoma (OAG).MethodsBetween October, 2012 and March, 2020 in a prospective interventional case series study. SCE device, made from 0.04 mm thick medical grade stainless steel wire, having inner lumen diameter of 0.12 mm and outer – 0.2 mm, 4–5 mm long was implanted into SC ab externo after completion of cataract surgery of 59 patients (38 male and 21 female; average age – 75.47 ± 6.2 years) suffering from OAG. Outcome measures were IOP change, number of glaucoma medications pre‐ and postoperatively and complications. Success rates were evaluated using World Glaucoma Association guidelines. A paired t‐test was used for analysis. Results were significant when p less than 0.05.ResultsMean preoperative IOP was 28+/–4.7mmHg and mean number of medications – 2.4 ± 0.8. At 4 years mean IOP reduced by 27%+/–15.5% and was 20,4+/–4,9 (n=59; p=.0000006) use of medications reduced to 1 ± 1.2 (p = 0.0000001). Complete success was achieved in 24% (14/59) cases and partial – in 49% (29/59) respectively. Intraoperatively, microperforation occurred in 5 cases (8.5%). Postoperatively, 6 cases (10%) required YAG laser trabeculopuncture to control IOP. In these cases, one end of SCE was lying in anterior chamber angle without contact with intraocular structures. Postoperatively, specific complications related to SCE were rare. In one case the body of SCE ruptured TM because of extra pressure put on eye ball while inserting goniolens. Both ends of the expander were embedded in SC. Patient’s IOP was under control with one medication.ConclusionsCombined surgery phacoemulsification with intraocular lens implantation and SCE implantation in surgical management of OAG in cataract patients show significant reduction in IOP from the baseline and in hypotensive medication(s) use in long‐term period.

Femtosecond laser surface roughening and pulsed plasma polymerization duplex treatment on medical-grade stainless steel substrates for orthodontic purpose

This study developed a surface modification technique to obtain nearly superamphiphobic films on AISI 304 stainless steel substrates, which are usually made into dental appliances in orthodontics for malocclusion. Direct fabrication of micro- and nanoscale roughened surfaces on stainless steel substrates were treated using femtosecond laser (FL) processing. Subsequently, pulsed plasma polymerization (P3) was adopted using hexamethyldisiloxane (C6H18OSi2) and octafluorocyclobutane (C4F8) as the precursors to deposit siloxane and fluorocarbon stacking films. The surface characteristics of the deposited films were examined, and in vitro cytotoxicity and antimicrobial tests were performed. Experimental results showed that the surfaces treated by FL and P3 processes exhibited nearly superamphiphobicity with water apparent contact angle (CA) 160°, advancing CA 161°, receding CA160°, contact angle hysteresis (CAH) 1°; sunflower oil apparent contact angle 146°, advancing CA 141°, receding CA137°, CAH 4°; and hexadecane oil apparent contact angle 124°, advancing CA 118°, receding CA113°, contact angle hysteresis CAH 5°, respectively. The nearly superamphiphobicity are attributed to the synergistic effects of pre-roughening by the FL process and post-flourinating with siloxane and fluorocarbon coating by the P3 process, which were consistent with the results of scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared analyses. In addition, the steel wool abrasion test exhibited the film's surface wear resistance, and in vitro tests revealed the film's non-cytotoxicity and effective inhibition of bacterial growth. Thus, the nearly superamphiphobic coating may be beneficial for applications in orthodontics.