Hybrid metasurface using graphene/graphitic carbon nitride heterojunctions for ultrasensitive terahertz biosensors with tunable energy band structure

Integrating novel materials is critical for the ultrasensitive,multi-dimensional detection of biomolecules in the terahertz(THz)range.Few studies on THz biosensors have used semiconductive active layers with tunable energy band structures.In this study,we demonstrate three THz biosensors for detecting casein molecules based on the hybridization of the metasurface with graphitic carbon nitride,graphene,and heterojunction.We achieved lowconcentration detection of casein molecules with a 3.54 ng/m L limit and multi-dimensional sensing by observing three degrees of variations(frequency shift,transmission difference,and phase difference).The favorable effect of casein on the conductivity of the semiconductive active layer can be used to explain the internal sensing mechanism.The incorporation of protein molecules changes the carrier concentration on the surface of the semiconductor active layer via the electrostatic doping effect as the concentration of positively charged casein grows,which alters the energy band structure and the conductivity of the active layer.The measured results indicate that any casein concentration can be distinguished directly by observing variations in resonance frequency,transmission value,and phase difference.With the heterojunction,the biosensor showed the highest response to the protein among the three biosensors.The Silvaco Atlas package was used to simulate the three samples'energy band structure and carrier transport to demonstrate the benefits of the heterojunction for the sensor.The simulation results validated our proposed theoretical mechanism model.Our proposed biosensors could provide a novel approach for THz metasurface-based ultrasensitive biosensing technologies.

Suppression of UsP8 sensitizes cells to ferroptosis via SQSTM1/p62-mediated ferritinophagy

Dear Editor,Ferroptosis is a newly discovered form of regulated cell death characterized by increased intracellular iron accumulation and subsequent lipid peroxidation(Dixon et al.,2012).Studies have revealed that ferroptosis plays an important role in multiple physiological and pathological processes including degenerative diseases,carcinogenesis,and cancer immunotherapy(Hassannia et al.,2019,Wang et al.,2019).

Sin1/mTORC2 regulate B cell growth and metabolism by activating mTORC1 and Myc

Proper control of B cell growth and metabolism is crucial for B-cell-mediated immunity,but the underlying molecular mechanisms remain incompletely understood.In this study,Sin1,a key component of mTOR complex 2(mTORC2),specifically regulates B cell growth and metabolism.Genetic ablation of Sin1 in B cells reduces the cell size at either the transitional stage or upon antigen stimulation and severely impairs metabolism.Sin1 deficiency also severely impairs B-cell proliferation,antibody responses,and anti-viral immunity.At the molecular level,Sin1 controls the expression and stability of the c-Myc protein and maintains the activity of mTORC1 through the Akt-dependent inactivation of GSK3 and TSC1/2,respectively.Therefore,our study reveals a novel and specific role for Sin1 in coordinating the activation of mTORC2 and mTORC1 to control B cell growth and metabolism.

Synthesis,structure,and luminescence properties of melilite Dy^(3+):Lu_(x)CaLa_(0.98-x)Ga_(3)O_(7) phosphors for use in yellow light-emitting devices

Dy^(3+) and Lu^(3+) co-doped CaLaGa_(3)O_(7) phosphors were prepared via high-temperature solid-phase reaction.The electronic structures of LuxCaLa_(0.98-x)Ga_(3)O_(7) were investigated by the first-principles calculations.The influence of Lu^(3+) on yellow light emission was studied using X-ray diffraction(XRD)and photoluminescence(PL) measurements.The XRD results indicate that compared to Dy^(3+):CaLaGa_(3)O_(7),the cell parameters of Dy^(3+):LuCaLaGa_(3)O_(7) tend to decrease,which is due to the smaller radius of Lu^(3+).When pumped by blue GaN laser diode(LD),the emission peaks of phosphors with different Lu^(3+)doping concentrations in the visible region are similar,with the strongest peak at 574 nm in the yellow light region,which is sensitive to human eyes.The optimal doping concentration of Lu^(3+) is confirmed to be1 at%,when all emission spectra and measured fluorescence lifetimes are taken into account.Moreover,the optimal phosphor composition Dy^(3+):Lu_(x)CaLa_(0.98-x)Ga_(3)O_(7)(x=0.01) has an internal quantum efficiency(IQE) of 46.94% and an external quantum efficiency(EQE) of 15.19%.Most notably,the prepared phosphor demonstrates excellent thermal stability and a high activation energy(0.203 eV).In addition,the International Illumination Commission color coordinates of the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7) phosphors are in the yellow light area.The above analysis indicates that the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7)(x=0.001)phosphor has promising application prospects in yellow light-emitting devices.