silicon and Leukemia

Developing novel strategies for sensitive and specific detection of protein biomarkers is a field of active research. Here, we report an ultrasensitive biosensor to detect protein tyrosine kinase-7 (PTK7), an important protein biomarker on the cell surface, by aptamer conformation-cooperated enzyme-assisted surface-enhanced Raman scattering (SERS) (ACCESS) technology. Our approach features a synergistic combination of the conformational alteration of the anglerfish aptamer triggered by the recognition of the membrane protein (PTK7) and Exo III enzyme-assisted nucleic acid amplification. It transduces the specific binding events between the aptamer and PTK7 protein into dramatically improved SERS signals. Sensitive and specific detection of PTK7 protein has been demonstrated both in the solution and directly on the surface of live CCRF-CEM cells, with a limit of detection better than the commercial enzyme-linked immunosorbent assay method by nearly 5 orders of magnitude. As a flexible, ultrasensitive, and specific approach, ACCESS promises important applications in clinical diagnostics, where only a very limited amount of the biological sample is available.

Topics: Aptamers, Nucleotide; Biological Assay; Biomarkers; Biosensing Techniques; Bone Marrow Cells; Cell Adhesion Molecules; Cell Line, Tumor; Exodeoxyribonucleases; Gold; Humans; Leukemia; Metal Nanoparticles; Receptor Protein-Tyrosine Kinases; Silicon; Spectrum Analysis, Raman

A platform of discrete microscopic magnetic elements patterned on a surface offers dynamic control over the motion of fluid-borne cells by reprogramming the magnetization within the magnetic bits. T-lymphocyte cells tethered to magnetic microspheres and untethered leukemia cells are remotely manipulated and guided along desired trajectories on a silicon surface by directed forces with average speeds up to 20 microm/s. In addition to navigating cells, the microspheres can be operated from a distance to push biological and inert entities and act as local probes in fluidic environments.

Topics: Cell Culture Techniques; Cell Line, Tumor; Cells, Cultured; Computer Simulation; Electromagnetic Fields; Humans; Leukemia; Microscopy; Microspheres; Models, Biological; Motion; Silicon; T-Lymphocytes; Video Recording

The present work aims at the development of a novel, diagnostic biosensor for monitoring asparagine levels in leukemia. Various immobilization strategies have been applied to improve the stability of the biocomponent (asparaginase). Response time studies have been carried out for different immobilization methods. Phenol Red indicator has been coimmobilized with asparaginase and color visualization approach has been optimized for various asparagine ranges. The detection limit of asparagine achieved with nitrocellulose membrane is 10(-1) M, with silicon gel is 10(-10)-10(-1) M, and with calcium alginate beads is 10(-9)-10(-1) M. Furthermore, the calcium alginate bead system of immobilization has been applied for the asparagine range detection in normal and leukemia serum samples.

Topics: Alginates; Asparaginase; Asparagine; Biosensing Techniques; Collodion; Enzymes, Immobilized; Escherichia coli K12; Glucuronic Acid; Hexuronic Acids; Humans; Indicators and Reagents; Leukemia; Microspheres; Phenolsulfonphthalein; Silicon