Trends in ultrashort and ultrahigh power laser pulses based on optical parametric chirped pulse amplification

Since the proof-of-principle demonstration of optical parametric amplification to efficiently amplify chirped laser pulses in 1992,optical parametric chirped pulse amplification(OPCPA)became the most promising method for the amplification of broadband optical pulses.In the meantime,we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers.The output power and pulse duration of these systems have ranged from a few gigawatts to hundreds of terawatts with a potential of tens of petawatts power level.Meanwhile,the output pulse duration based on optical parametric amplification has entered the range of fewoptical-cycle field.In this paper,we overview the basic principles,trends in development,and current state of the ultrashort and laser systems based on OPCPA,respectively.     

Poly‐ε‐Lysine Modified Nanocarbon Film Electrodes for LPS Detection

We developed an electrochemical system for detecting lipopolysaccharide (LPS) that uses an ultraflat nanocarbon film electrode modified with poly‐ε‐lysine with a high affinity to LPS. LPS was captured on the modified electrode, and then ferrocene labeled polymyxin B (FcPMB) was captured on the LPS adsorbed electrode via the LPS‐PMB affinity interaction. The adsorbed FcPMB provided an amplified response with Fe²⁺ ions, and the current response was dependent on the amount of captured LPS (LOD=2.0 ng/mL). This was due to the efficient accumulation of the obtained current for LPS and the very low noise made possible by the ultraflat surface.     

Toehold‐initiated Rolling Circle Amplification for Visualizing Individual MicroRNAs In Situ in Single Cells

The ability to quantitate and visualize microRNAs (miRNAs) in situ in single cells would greatly facilitate the elucidation of miRNA‐mediated regulatory circuits and their disease associations. A toehold‐initiated strand‐displacement process was used to initiate rolling circle amplification of specific miRNAs, an approach that achieves both stringent recognition and in situ amplification of the target miRNA. This assay, termed toehold‐initiated rolling circle amplification (TIRCA), can be utilized to identify miRNAs at physiological temperature with high specificity and to visualize individual miRNAs in situ in single cells within 3 h. TIRCA is a competitive candidate technique for in situ miRNA imaging and may help us to understand the role of miRNAs in cellular processes and human diseases in more detail.     

Self‐Replication and Amplification of Enantiomeric Excess of Chiral Multifunctionalized Large Molecules by Asymmetric Autocatalysis

Self‐replication of large chiral molecular architectures is one of the great challenges and interests in synthetic, systems, and prebiotic chemistry. Described herein is a new chemical system in which large chiral multifunctionalized molecules possess asymmetric autocatalytic self‐replicating and self‐improving abilities, that is, improvement of their enantioenrichment in addition to the diastereomeric ratio. The large chiral multifunctionalized molecules catalyze the production of themselves with the same structure, including the chirality of newly formed asymmetric carbon atoms, in the reaction of the corresponding achiral aldehydes and reagent. The chirality of the large multifunctionalized molecules controlled the enantioselectivity of the reaction in a highly selective manner to construct multiple asymmetric stereogenic centers in a single reaction.     

A novel signal-on fluorescent aptasensor for ochratoxin A detection based on RecJf exonuclease-induced signal amplification

This article describes a simple and homogeneous fluorescent aptasensor for the detection of ochratoxin A (OTA). With its high specificity and simplicity; RecJ_f exonuclease is used to cleave DNA strand of the FAM-aptamer/OTA complex and realize target recycling signal amplification. In order to avoid the loss of reaction system, magnetic beads (MBs) are added only once at the last experimental step. This proposed fluorescent aptasensor showed the higher sensitivity in the range of 0.1–100 ng/mL with LOD of 0.056 ng/mL, and the good selectivity against other interfering toxins. The feasibility of the prepared aptasensor was studied by detecting OTA in spiked liquor and cereal samples. The obtained average recoveries ranged from 92% to 115%. This study provides a promising application with convenience and rapidness in the aptasensor fabrication for food safety analysis.     

Fluorescence Signal Amplification Strategies Based on DNA Nanotechnology for miRNA Detection

In this review,the most recent progresses in the field of fluorescence signal amplification strategies based on DNA nanotechnology for miRNA are summarized.The types of signal amplification are given and the principles of amplification strategies are explained,including rolling circle amplification(RCA),catalytic hairpin assembly(CHA),hybridization chain reaction(HCR)and DNA walker.Subsequently,the application of these signal amplification methods in biosensing and bioimaging are covered and described.Finally,the challenges and the outlook of fluorescence signal amplification methods for miRNA detection are briefly commented.     

Nanostructures of noble metals as functional materials in biosensors

Recent advancement in nanoscience and nanotechnologies inspired a wide spectrum of uses of nanodimensional materials ranging from industrial sector to biomedical applications. Inorganic nanomaterials made of noble metals, which are corrosion-resistant, are often included as electrode modifiers in designing electrochemical chemosensors and biosensors because of their unique catalytic, electric, and surface-related properties. This review summarizes the developments in electrochemical biosensors with integrated in their architecture metal nanostructures reported mainly during the last two years with a summary on some of the commonly used methods for the synthesis of metallic nanostructures. Nanodimensional noble metal structures might be considered as multipurpose electrode modifiers because of their abilities to act at the same time as electrocatalysts, signal amplifiers, and tools for immobilization and spatial orientation of redox proteins/enzymes or other type of bioreceptors.     

用于宽带啁啾脉冲光参量放大系统精确同步的新方法

基于非共线光参量放大,以波长800 nm飞秒激光的倍频光为抽运光,以激光二极管640 nm连续波激光为信号光,产生了与800 nm飞秒激光精确同步的无直流本底的1064 nm脉冲光。实验结果显示该1064 nm的光脉冲在脉冲能量和空间光束质量上均可作为1064 nm波长脉冲放大器的种子光。仅通过一级简单紧凑的非共线参量放大就可实现光周期量级的光参量啁啾脉冲放大系统的抽运激光和种子光的精确同步。     

饱和放大情形下光纤参量放大器的增益和带宽特性研究

利用龙格库塔法数值求解非线性耦合方程,研究了单抽运光纤参量放大器在增益饱和区的增益谱特性.通过比较考虑抽运光损耗与忽略抽运光损耗增益谱的差别,分析了抽运光损耗对增益谱的影响.此外,给出了在饱和放大区,信号光的增益谱与光纤长度、输入信号光功率、抽运光波长与零色散波长偏离之间的关系.发现在饱和放大区,增益的整体水平有所下降,增益谱的可用带宽相对于小信号放大有所减少,增益谱在可用带宽范围内出现了旁瓣.这些结果将对工作在饱和放大区的单抽运光参量放大器的设计提供有益的帮助.     

5 TW/40 fs级台式钛宝石激光系统研究

在TSA-25系统输出35 mJ,800 nm啁啾脉冲的基础上,建立了以钛宝石作为增益介质的二级啁啾脉冲放大(CPA)系统。使用0.6 J和1.6 J,532 nm,10 Hz Nd∶YAG激光抽运,输出脉冲能量达到500 mJ,经压缩脉冲宽度为41 fs,压缩器的能量转换效率为63%,峰值功率可达7.6 TW。通过对放大器系统的钛宝石晶体、抽运密度以及多通结构通道数的选择等实验,有效地提高了能量放大器的萃取效率。其主放大器能量萃取效率达到32%,整个系统占用尺寸不到10 m2。