The amino acids sequences alignment of mutliple 6-phosohate ascorbic acid lactonase amino acid from different <i>Streptococcus</i> species, including <i>S</i>. <i>pneumoniae</i> ATCC 49136, <i>S</i>. <i>agalactiae</i> A909, <i>S</i>. <i>equi</i> 2329, <i>S</i>. <i>mitis</i> 21/39, <i>S</i>. <i>mutans</i> UA159, <i>S</i>. <i>porcinus</i> Str. Jelinkova 176, <i>S</i>. <i>pyogenes</i> GA40634, <i>S</i>. <i>suis</i> R61, <i>S</i>. <i>sanguinis</i> SK353, and, <i>S</i>. <i>uberis</i> B362.

<p>The amino acids sequences alignment of mutliple 6-phosohate ascorbic acid lactonase amino acid from different <i>Streptococcus</i> species, including <i>S</i>. <i>pneumoniae</i> ATCC 49136, <i>S</i>. <i>agalactiae</i> A909, <i>S</i>. <i>equi</i> 2329, <i>S</i>. <i>mitis</i> 21/39, <i>S</i>. <i>mutans</i> UA159, <i>S</i>. <i>porcinus</i> Str. Jelinkova 176, <i>S</i>. <i>pyogenes</i> GA40634, <i>S</i>. <i>suis</i> R61, <i>S</i>. <i>sanguinis</i> SK353, and, <i>S</i>. <i>uberis</i> B362.</p

Localization of MBL.

<p>(A) Fluorescence microscopic detection of GFP (i) and MBL-GFP (ii) in <i>E</i>.<i>coli</i>. (B) Upper panel illustrates the immunoprecipitation of bacteria cells with antibody-conjugated magnetic nanoparticles (MNP). Lower panel reveal the PCR products of varied amount of bacteria immunoprecipitated with MBL specific antibody-conjugated magnetic Fe₃O₄ nanoparticles (MNP) and subsequent PCR using streptococci-specific primers that recognize the lytA gene.</p

Schemematic illustration of the mechanism of ampicillin resistance of MBL in <i>S</i>. <i>pneumonia</i> cells.

<p>Schemematic illustration of the mechanism of ampicillin resistance of MBL in <i>S</i>. <i>pneumonia</i> cells.</p

An Ultrasensitive Nanowire-Transistor Biosensor for Detecting Dopamine Release from Living PC12 Cells under Hypoxic Stimulation

Dopamine (DA) is an important neurotransmitter that is involved in neuronal signal transduction and several critical illnesses. However, the concentration of DA is extremely low in patients and is difficult to detect using existing electrochemical biosensors with detection limits typically around nanomolar levels (∼10^–9 M). Here, we developed a nanoelectronic device as a biosensor for ultrasensitive and selective DA detection by modifying DNA-aptamers on a multiple-parallel-connected (MPC) silicon nanowire field-effect transistor (referred to as MPC aptamer/SiNW-FET). Compared with conventional electrochemical methods, the MPC aptamer/SiNW-FET has been demonstrated to improve the limit of DA detection to <10^–11 M and to possess a detection specificity that is able to distinguish DA from other chemical analogues, such as ascorbic acid, catechol, phenethylamine, tyrosine, epinephrine, and norepinephrine. This MPC aptamer/SiNW-FET was also applied to monitor DA release under hypoxic stimulation from living PC12 cells. The real-time recording of the exocytotic DA induced by hypoxia reveals that the increase in intracellular Ca²⁺ that is required to trigger DA secretion is dominated by an extracellular Ca²⁺ influx, rather than the release of intracellular Ca²⁺ stores