Surface modification of stainless steel for biomedical applications: Revisiting a century-old material

Stainless steel (SS) has been widely used as a material for fabricating cardiovascular stents/valves, orthopedic prosthesis, and other devices and implants used in biomedicine due to its malleability and resistance to corrosion and fatigue. Despite its good mechanical properties, SS (as other metals) lacks biofunctionality. To be successfully used as a biomaterial, SS must be made resistant to the biological environment by increasing its anti-fouling properties, preventing biofilm formation (passive surface modification), and imparting functionality for eluting a specific drug or capturing selected cells (active surface modification); these features depend on the final application. Various physico-chemical techniques, including plasma vapor deposition, electrochemical treatment, and attachment of different linkers that add functional groups, are used to obtain SS with increased corrosion resistance, improved osseointegration capabilities, added hemocompatibility, and enhanced antibacterial properties. Existing literature on this topic is extensive and has not been covered in an integrated way in previous reviews. This review aims to fill this gap, by surveying the literature on SS surface modification methods, as well as modification routes tailored for specific biomedical applications. STATEMENT OF SIGNIFICANCE: Stainless steel (SS) is widely used in many biomedical applications including bone implants and cardiovascular stents due to its good mechanical properties, biocompatibility and low price. Surface modification allows improving its characteristics without compromising its important bulk properties. SS with improved blood compatibility (blood contacting implants), enhanced ability to resist bacterial infection (long-term devices), better integration with a tissue (bone implants) are examples of successful SS surface modifications. Existing literature on this topic is extensive and has not been covered in an integrated way in previous reviews. This review paper aims to fill this gap, by surveying the literature on SS surface modification methods, as well as to provide guidance for selecting appropriate modification routes tailored for specific biomedical applications.Accepted manuscrip

Multiplexed detection of cancer biomarkers using an optical biosensor

Early detection of cancer is important in administering timely treatment and increasing cancer survival rates. For early cancer detection one can use biomarkers, which are characteristics that can be objectively measured or evaluated as indicators of normal or pathogenic processes. In our study we study three protein biomarkers: carcinoembryonic antigen (CEA), interleukin-6 (IL-6) and extracellular protein kinase A (ECPKA), which have been implicated in various types of human cancer. The main objective of this project is to develop a biosensor for detection of multiple cancer biomarkers. To detect these protein biomarkers high affinity ssDNA aptamers are being selected. Aptamers are short single stranded DNAs with an ability to bind to various targets with high affinity and specificity which selected by SELEX (Systemic Evolution of Ligands through Exponential enrichment) [2]. Ultimately, aptamers against each of the biomarker will be conjugated to magnetic nanoparticles to capture biomarkers from biological fluids. Another aptamer is proposed to be conjugated to quantum dots for quantitation of biomarkers when analyzed on spectrometer

Multiplexed detection of cancer biomarkers using an optical biosensor

Early detection of cancer is important in administering timely treatment and increasing cancer survival rates. For early cancer detection one can use biomarkers, which are characteristics that can be objectively measured or evaluated as indicators of normal or pathogenic processes. In our study we study three protein biomarkers: carcinoembryonic antigen (CEA), interleukin-6 (IL-6) and extracellular protein kinase A (ECPKA), which have been implicated in various types of human cancer. The main objective of this project is to develop a biosensor for detection of multiple cancer biomarkers. To detect these protein biomarkers high affinity ssDNA aptamers are being selected. Aptamers are short single stranded DNAs with an ability to bind to various targets with high affinity and specificity which selected by SELEX (Systemic Evolution of Ligands through Exponential enrichment) [2]. Ultimately, aptamers against each of the biomarker will be conjugated to magnetic nanoparticles to capture biomarkers from biological fluids. Another aptamer is proposed to be conjugated to quantum dots for quantitation of biomarkers when analyzed on spectrometer

Mycobacterium tuberculosis lineage 4 comprises globally distributed and geographically restricted sublineages

Generalist and specialist species differ in the breadth of their ecological niches. Little is known about the niche width of obligate human pathogens. Here we analyzed a global collection of Mycobacterium tuberculosis lineage 4 clinical isolates, the most geographically widespread cause of human tuberculosis. We show that lineage 4 comprises globally distributed and geographically restricted sublineages, suggesting a distinction between generalists and specialists. Population genomic analyses showed that, whereas the majority of human T cell epitopes were conserved in all sublineages, the proportion of variable epitopes was higher in generalists. Our data further support a European origin for the most common generalist sublineage. Hence, the global success of lineage 4 reflects distinct strategies adopted by different sublineages and the influence of human migration.We thank S. Lecher, S. Li and J. Zallet for technical support. Calculations were performed at the sciCORE scientific computing core facility at the University of Basel. This work was supported by the Swiss National Science Foundation (grants 310030_166687 (S.G.) and 320030_153442 (M.E.) and Swiss HIV Cohort Study grant 740 to L.F.), the European Research Council (309540-EVODRTB to S.G.), TB-PAN-NET (FP7-223681 to S.N.), PathoNgenTrace projects (FP7-278864-2 to S.N.), SystemsX.ch (S.G.), the German Center for Infection Research (DZIF; S.N.), the Novartis Foundation (S.G.), the Natural Science Foundation of China (91631301 to Q.G.), and the National Institute of Allergy and Infectious Diseases (5U01-AI069924-05) of the US National Institutes of Health (M.E.)

Functionalized etched tilted fiber Bragg grating aptasensor for label-free protein detection

An aptasensor based on etched tilted fiber Bragg grating (eTFBG) is developed on a single-mode optical fiber targeting biomolecule detection. TFBGs were chemically etched using hydrofluoric acid (HF) to partially remove the fiber cladding. The sensor response was coarsely interrogated, resulting on a sensitivity increase from 1.25 nm/RIU (refractive index unit) at the beginning of the process, up to 23.38 nm/RIU at the end of the etching, for a RI range from 1.3418 to 1.4419 RIU. The proposed aptasensor showed improved RI sensitivity as compared to the unetched TFBG, without requiring metal depositions on the fiber surface or polarization control during the measurements. The proposed sensor was tested for the detection of thrombin-aptamer interactions based on silane-coupling surface chemistry, with thrombin concentrations ranging from 2.5 to 40 nM. Functionalized eTFBGs provided a competitive platform for biochemical interaction measurements, showing sensitivity values ranging from 2.3 to 3.3 p.m./nM for the particular case of thrombin detection

Development of an optical biosensor for diagnosis of tuberculosis

Tuberculosis (TB) is an airborne disease caused by Mycobacterium tuberculosis. TB is the leading cause of morbidity and mortality in the developing world. Early and accurate diagnosis of TB would greatly enhance the treatment and prevention of the disease. Current methods of TB detection suffer from various limitations such as low specificity and sensitivity, being too complex and expensive. In the present work, we aim to develop an optical biosensor based on DNA aptamers, quantum dot (QD) crystals and magnetic nanoparticles (MNP) for detection of MPT64 protein, specific to M.tuberculosis. Aptamer-MNP conjugate is used for separation of MPT64 from solution, while aptamer-QD is used to detect its presence afterwards using fluorometer