A novel strategy for screening early hepatocellular carcinoma (HCC) using a terahertz (THz) metamaterials (MMs) biosensor modified with the antibody against Alpha-Fetoprotein (AFP) is proposed. The designed biosensor consists of split-resonant-rings (SRRs) with double resonant frequencies that are optimized using the finite integration time domain (FITD) method and manufactured by a surface micromachining process. The experimental results indicate that the HCC biomarker AFP could be accurately distinguished with a concentration as low as 0.1 ng/ml via analyzing the shifts of double resonant frequencies. Meanwhile, specific detection of AFP-antigen in solution and HCC serum has been achieved through the antigen-antibody specific binding. These results demonstrate the sensitivity and specificity of THz MMs biosensor for molecular detection of trace cancer biomarkers in biochemical sensing. Furthermore, the sensitivity of specific cancer biomarkers can be further improved by optimizing the metamaterial structure and applying the double resonant frequencies. Therefore, this approach may own great potential for special identification of early cancer molecules.

We present an investigation of high harmonic generation (HHG) from relativistic plasmas driven by two-color co-rotating circularly polarized (CP) laser fields at various frequency ratios ${\omega }_2/{\omega }_1$ . The theoretical analysis and the particle-in-cell simulation results reveal that when ${\omega }_2/{\omega }_1\ge 4$ , CP harmonics with opposite helicities can appear simultaneously due to the relativistic mirror effect and the related conservation laws. Meanwhile, the harmonic spectra features (including the HHG efficiency, the allowed harmonic orders, and their polarization states) can be tuned through adjusting the frequency and intensity ratio of the two driving field components. This finding might be helpful for a consummate understanding of the bi-circular HHG technique.

High harmonic generation (HHG) by two-color counter-rotating relativistic laser pulses with arbitrary frequency ratio is investigated through particle-in-cell simulations. It is shown that the dichromatic laser driver at various frequency ratios can effectively produce high-order harmonics with different spectral features. A general selection rule of this extended scheme can be obtained and the corresponding harmonic helicity can be identified through a simple analytical model based on a relativistic oscillating mirror. Thus, the results in this paper may offer new opportunities for arbitrary spectral control of generated harmonics, which is of significance for diverse potential applications in practice.

Alpha-fetoprotein (AFP) is closely associated with the occurrence and development of hepatocellular carcinoma (HCC). However, for many HCC patients at early-stage, the AFP concentration is very low and difficult to test. Herein, a terahertz (THz) metamaterials (MMs) biosensor modified with AFP antibody (ATB-AFP) and aptamer (APT-AFP) polymer probe was proposed to detect trace AFP. The biosensor has a theoretical sensitivity of 124 GHz/RIU (Refractive Index Unit), and its experimental limit-of-detection (LOD) is 0.1 ng/mL. When it is modified with AuPEG ₂₀₀₀ -ATB-AFP and AuPEG ₂₀₀₀ -APT-AFP, it sensitivity for AFP antigen in HCC serum is 17.74 GHz/lg(ng/mL) and 15.89 GHz/lg(ng/mL), respectively. The proposed biosensor could detect trace biomarkers at the molecular level, which is significant for diagnosis of the HCC and many other cancers at early stage.

The ‘windows’ or ‘doors’ on the surface of a closed hollow structure can enable the exchange of material and information between the interior and exterior of one hollow sphere or between two hollow spheres, and this information or material exchange can also be controlled through altering the window’ size. Thus, it is very interesting and important to achieve the fabrication and adjustment of the ‘windows’ or ‘doors’ on the surface of a closed hollow structure. In this paper, we propose a new method based on the temple-assisted deposition method to achieve the fabrication of hollow spheres with windows of accurate size and number. Through precisely controlling of deposition parameters (i.e., deposition angle and number), hollow spheres with windows of total size from 0% to 50% and number from 1 to 6 have been successfully achieved. A geometrical model has been developed for the morphology simulation and size calculation of the windows, and the simulation results meet well with the experiment. This model will greatly improve the convenience and efficiency of this temple-assisted deposition method. In addition, these hollow spheres with desired windows also can be dispersed into liquid or arranged regularly on any desired substrate. These advantages will maximize their applications in many fields, such as drug transport and nano-research container.