ABSTRACT
The Na(+) concentration near membranes controls our nerve signals aside from several other crucial bioprocesses. Fluorescent photoinduced electron transfer (PET) sensor molecules target Na(+) ions in nanospaces near micellar membranes with excellent selectivity against H(+). The Na(+) concentration near anionic micelles was found to be higher than that in bulk water by factors of up to 160. Sensor molecules that are not held tightly to the micelle surface only detected a Na(+) amplification factor of 8. These results were strengthened by the employment of control compounds whose PET processes are permanently "on" or "off".
Subject(s)
Micelles , Sodium/analysis , Electron Transport , Fluorescence , Spectrometry, Fluorescence , Surface PropertiesABSTRACT
We demonstrate a compact, low cost and practical fluorescence detection system for lab-on-a-chip applications. The system comprises a commercially available InGaN light emitting diode (501 nm) as light source, an organic or silicon photodiode detector, absorptive dye coated colour filters and linear and reflective polarisers. An injection moulded polystyrene microfluidic chip is used as the platform for fluorescence immunoassays for cardiac markers myoglobin and CK-MB. The optical limit of detection (LOD) is measured using a TransFluoSphere® suspension at 5.6 × 10(4) beads µl(-1) which can be equated to â¼3 nM fluorescein equivalent concentration. The LOD for the human plasma immunoassays is measured as 1.5 ng ml(-1) for both myoglobin and CK-MB.
Subject(s)
Fluorescent Antibody Technique/methods , Lab-On-A-Chip Devices , Microfluidic Analytical Techniques/methods , Biomarkers/blood , Creatine Kinase, MB Form/blood , Humans , Myoglobin/blood , Point-of-Care Systems , Sensitivity and SpecificityABSTRACT
We demonstrate the first three-input molecular AND logic gate based on three chemical inputs as a direct way of detecting congregations of chemical species. The AND gate operates in water and responds to Na+, H+, and Zn2+ inputs with an enhanced fluorescence signal when pre-set concentration thresholds are exceeded. Future "lab-on-a-molecule" devices could have application in medicine for rapid disease screening.
ABSTRACT
Molecular computation is fashionable because of the small device sizes that should be possible. For instance, information processing in nanospaces is widespread in biology. However, experimental cases with computing molecules occupy rather large volumes until now (ca. 1012 nm3). Now we demonstrate small-scale computation using a designed logic gate in spheres of 3 nm radius (volume = ca. 102 nm3) which are produced by detergent micelles. The logic gate accommodated in the small nanospace fluoresces only when both H+ and Na+ ions are available.
Subject(s)
Computer Simulation , Computers, Molecular , Membranes, Artificial , Nanostructures/chemistry , Equipment Design , Fluorescence , Hydrogen-Ion Concentration , Micelles , Molecular Structure , Quaternary Ammonium Compounds/chemistry , Sodium/chemistry , Sodium Dodecyl Sulfate/chemistry , Spectrometry, FluorescenceABSTRACT
Sensor 1 signals the simultaneous presence of sodium and phosphate with an increased fluorescence signal in the manner of a photoionic AND logic gate.
