Preparation of carboxylated magnetic nanoparticle (MNPs) MNPs were synthesized according to the hydrothermal method with slight modification [50]

Preparation of carboxylated magnetic nanoparticle (MNPs) MNPs were synthesized according to the hydrothermal method with slight modification [50]. in whole blood was decided to be 10 ng mL-1 (S/N=3) with a linear dynamic range of 10 to 200 ng mL-1. This study provides a quick and low-cost approach for detecting proteins in blood, showing great promise for clinical application and biomedical diagnosis, particularly in limited resource settings. strong class=”kwd-title” Keywords: Magnetized carbon nanotube, lateral circulation, biosensor, protein, blood Graphical abstract Combining the superpara-magnetism of Fe3O4 nanoparticles and the outstanding mechanical properties of carbon nanotubes, magnetized carbon nanotube-based lateral circulation strip biosensor was first used for visual detection of proteins directly in whole blood avoiding complex purification and sample pretreatment. 1. Introduction Protein, involved in a variety of life events, plays crucial roles in metabolism [1]. To sensitively detect proteins is usually of enormous interest for not only basic discovery research but also a broad range of applications, such as biology, disease diagnosis, food security, and environmental analysis [2,3]. However, detecting proteins in physiological fluid samples, particularly in blood, is still a great challenge because of problems such as biofouling and nonspecific binding, and producing need to use sample purification greatly reduces the clinical applications [4]. Traditional techniques to quantify the protein concentrations in blood include Radioimmunoassay [5,6], Benzyl alcohol Western Blot [7,8], agarose and polyacrylamide gel electrophoresis [9], Enzyme-linked Immunosorbent Assay (ELISA) [10-13] and Mass Spectrometry (MS) [14-15]. However, these technologies are limited to laboratory use because they rely on sample purifications and sophisticated instruments, are time and labour rigorous and expensive, and require highly trained personals. Numerous immunoassays and immunosensors in connection with different transducers (electrochemical, optical, acoustic, piezoelectric, etc.) have been reported to detect proteins in blood [16-23]. Although many of them have been applied at the laboratory research level, they have not been applied in-field or point-of-care detection because of the relatively long assay time or multiple washing and separation actions. Lateral circulation immunoassay (LFI), also known as immunochromatographic assay or lateral circulation strip biosensor (LFSB), is usually a solid-phase immunoassay incorporating the technology of thin layer chromatography and immune recognition reaction. LFI is one of quick, cost-effectiveness and portable detection techniques. LFI has been utilized for point-of-care or in-field screening of infectious diseases, drugs of abuse, and pregnancy [24-30]. Platinum nanoparticles (GNPs), carbon nanoparticles, quantum dots (QDs) and Fe3O4 nanoparticles have been used as immunochromatographic labels among which GNPs are the most widely used due to their unique optical properties (plasma absorption) and easy surface modification [31-36]. However, GNP-based LFIs are not able to detect proteins with low concentrations in whole blood due to its low sensitivities and colour interference. Fluorescent and magnetic LFIs have drawn considerable interest because of their high sensitivities and anti-interferences. Gerd et al. reported a lateral circulation immunoassay using europium (III) chelate microparticles and time-resolved fluorescence for eosinophils and Rabbit Polyclonal to MINPP1 neutrophils in whole blood [37]. Own to unique magnetic separation properties, magnetic microparticles and nanoparticles have been used as immunochromatographic labels for the detection Benzyl alcohol of analytes in food matrixes [35, 38]. However, fluorescent and magnetic LFIs still require expensive or complex readers. Therefore, there is still a great challenge to develop inexpensive, quick and easy-to-use technologies for protein detection in whole blood. Since their discovery by Iijima, carbon nanotubes (CNTs) have been used to construct various chemical sensors and biosensors because of their unique physical, chemical and electronical properties [39,40]. Most of the CNT-based biosensors and bioassays still suffered from tedious assay time, multiple washing actions and the requirement of trained staff [41-44]. Our group Benzyl alcohol as well as others have reported CNT-based.