Procalcitonin (PCT) is an early and highly specific biomarker in response to bacterial infection. The PCT-guided antibiotic therapy has demonstrated to be more efficient than standard therapy to reduce in antibiotic use without adverse outcome in mortality. The PCT detection in clinics is required to be highly sensitive with a sensitivity of 0.5 ng/ml. At present, the technologies for PCT detection are limited. This paper reported a highly sensitive nanoimprinted gold nanopillar array chip for PCT detection. To achieve high sensitivity for PCT detection, the gold nanopillar array sensing chip was designed by plasmonic simulation and fabricated by high fidelity nanoimprinting technology. The gold nanopillars of 140 nm were nanoimprinted on glass substrate. A robust sandwich bioassay of capture antibody /PCT / quantum dot (QD) conjugated detection antibody was established on the gold nanopillar array chip to detect PCT. The nanopillars serve as localized surface plasmon resonance (LSPR) generators to enhance the fluorescent emission from QD. A limit of detection (LOD) of 0.5 ng/ml was achieved for PCT detection. This is the first time that PCT is detected with such high sensitivity by LSPR enhanced QD emission. By considering the low-cost, high sensitivity of the bioassay, as well as the inexpensive mass fabrication of the high quality chips, this novel nanoimprinted gold nanopillar array chip is particularly useful for developing a point-of-care system for PCT detection.
The design and fabrication of gold nanostructures through nanosphere lithography utilizing dispersed nanospheres, on glass substrate for the applications of localized surface plasmon resonance, were investigated in detail. The fabrication of the nanostructures was realized through the gold film deposition onto nanospheres dispersed on a substrate and the subsequent directional gold etching. Depending on the deposition and etching conditions of the gold, a variety of gold nanostructures can be fabricated. So far through this method, only 2D nanocrescents had been reported. However, either 2D or 3D non-conformal nanostructures are formed in this way, and the profiles of the obtainable nanostructures were simulated under various conditions. For nanostructures fabricated on glass, the simulated profiles coincided well with the fabricated ones. These results prove that our profile simulation program can realize the design of 2D and 3D nanostructures obtainable by dispersed nanospheres, and reduce the effort and cost for achieving desired nanostructures by experiments in the trial-and-error stage.
This paper reports the details regarding the design and fabrication of gold nanostructures on glass substrates through
nanosphere lithography (NSL) for the application of localized surface plasmon resonance (LSPR), which can be used for
biosensors. It is realized through gold film deposition on nanospheres dispersed on a surface and subsequent anisotropic
etching. Depending on the gold deposition and etching conditions, a variety of gold nanostructure shapes can be
obtained. So far through this method, only 2D nanocrescents are reported. In this paper it is pointed out that both 2D and
3D non-conformal nanostructures can be fabricated, and some 2D and 3D profiles of the obtainable nanostructures are
simulated by our programs under various deposition and etching conditions. The fabrication processes of the
nanostructures on glass substrates are also reported, and the simulated profiles of such nanostructures coincide well with
the experimental results. These results prove that our profile simulation program can realize the design of 2D and 3D
nanostructures obtainable by nanosphere lithography, and reduce the effort and cost for achieving optimized
nanostructures by experiments in the trial and error stage.
This paper puts forward a new method to overcome the polarization-induced fading (PIF) in conventional low- birefringence optical fiber constructed interferometric sensors arrays. By inducing high frequency modulation to the state of polarization at the output end of the array, the maximum PIF variation of each sensor's signal is 4.7dB or 6.3dB according to the selection of modulation signal. Combined with an electronic automatic gain control circuit or dividing each sensor's signal by its visibility, each sensor's signal fading is recovered at the expense of a relevant signal/noise degradation of 4.7dB or 6.3dB.
As polarization-induced fading is commonly exists in interferometric fiber-optic sensors and their arrays. This paper proposed a method for input polarization control in interferometric fiber-optic sensor arrays. Here, the signal used to control the input polarization state of the multiplexing system is the weighted sum of each sensor's feedback signal for its optimum input control. The suitable feedback signal in a single fiber-optic sensor is presented, and the feasibility for arrays' input polarization control is discussed. The theoretical result of the lowest control visibility is approximate to the ideal value of sin[(pi) /(2N+2)].