Nanoimmunosensor based on ZnO nanorods for ultrasensitive detection of 17ß-Estradiol.

Advances in nanostructured materials have facilitated the development of novel sensitive techniques for detection of environmental and clinical analytes. There is immense need for development of devices that can detect analytes at concentrations as low as few pg mL-1. The comparable size of nanostructured materials and biomolecules enabled the integration of biological systems with nanometer sized structures. Herein, we demonstrate a Zinc Oxide nanorods (ZnONRs) integrated ultrasensitive label-free biosensor with femtomolar (0.01 pg mL-1) sensitivity for the endocrine disruptor 17ß-Estradiol (E2). The ZnONRs, average width 50 nm and length 325 nm, were grown on the silver electrode surface (Ag-ZnONRs). Monoclonal antibodies of E2 (mAb-E2) were covalently immobilized on ZnONRs surface and measured using electrochemical impedance spectroscopy (EIS). A linear detection range of 0.1-200 pg mL-1 for E2 with R2 = 0.99 and % RSD = 4.35 (n = 3, assay volume 90 µL) was achieved for the developed nano-sensing system. A significant enhancement in the sensitivity was achieved in the presence of ZnONRs, enabling the limit of quantification down to 0.1 pg mL-1 with 2.7 % capacitance change per decade. In addition, a further increase in sensitivity due to assay volume reduction (20 µL) was observed enabling further scope of miniaturization.

Intracellular ZnO Nanorods Conjugated with Protoporphyrin for Local Mediated Photochemistry and Efficient Treatment of Single Cancer Cell.

ZnO nanorods (NRs) with high surface area to volume ratio and biocompatibility is used as an efficient photosensitizer carrier system and at the same time providing intrinsic white light needed to achieve cancer cell necrosis. In this letter, ZnO nanorods used for the treatment of breast cancer cell (T47D) are presented. To adjust the sample for intracellular experiments, we have grown the ZnO nanorods on the tip of borosilicate glass capillaries (0.5 µm diameter) by aqueous chemical growth technique. The grown ZnO nanorods were conjugated using protoporphyrin dimethyl ester (PPDME), which absorbs the light emitted by the ZnO nanorods. Mechanism of cytotoxicity appears to involve the generation of singlet oxygen inside the cell. The novel findings of cell-localized toxicity indicate a potential application of PPDME-conjugated ZnO NRs in the necrosis of breast cancer cell within few minutes.

Differential transcriptional expression following thidiazuron-induced callus differentiation developmental shifts in rice.

Very little is known about molecular events associated with callus differentiation in indica rice. The genes expressed differentially during shoot meristem initiation were identified on genomic arrays applied to efficiently regenerating rice calli. A thidiazuron (TDZ; N-phenyl-N-thiadiazol-1,2,3-5,ylurea)-dependent regeneration protocol was developed for efficient embryogenesis in indica rice. The regenerating embryogenic calli induced by TDZ for 10 days showed transcriptional modulation of a number of genes associated with photosynthesis, hormone metabolism, plant development, signal transduction, light response, and plant defense. Eighteen candidate miRNAs were predicted to target the genes expressed differentially in the embryogenic calli grown in TDZ-containing medium. The majority of the photosynthesis-related genes up-regulated in differentiating calli were not expressed or were down-regulated in developing seeds and inflorescences. Most of the genes down-regulated in differentiating calli were up-regulated in developing seeds. The transcriptome of differentiating callus most closely resembled that of the germinating whole seed.

Selective calcium ion detection with functionalized ZnO nanorods-extended gate MOSFET.

Zinc oxide nanorod-extended gate field effect transistor (MOSFET) is demonstrated for the detection of calcium (Ca(2+)) ions. ZnO nanorods were grown on the surface of a silver wire to produce an electrochemical nanosensor for selectively detecting Ca(2+). The electrochemical response from the interaction between the ZnO nanorods and Ca(2+) in an aqueous solution is coupled directly to the gate of a field effect transistor (MOSFET). The induced voltage change on the gate results in a measureable current response. In order to adapt the sensors for Ca(2+) ions measurements in biological fluids with sufficient selectivity and stability, a plastic membrane coating containing ionophores was applied on the nanorods. The sensor exhibited a linear response within the range of interest from 1 microM to 1 mM. This work demonstrates a simple technique for sensitive detection of Ca(2+) ions by efficient transfer of the chemical response directly to a standard electronic component producing a low impedance signal.