Nano-imaging agents for brain diseases: Environmentally responsive imaging and therapy

Precise imaging is essential for the accurate diagnosis and surgical guidance of brain diseases but it is challenging due to the difficulties in crossing the blood-brain barrier(BBB),the difficulties in disease lesion targeting,and the limited contrast in the brain environment.Nano-imaging agents were characterized by functionalized modifications,high contrast,small size,and high biocompatibility,thus providing advantages in BBB crossing,brain targeting,imaging resolution,and real-time monitoring,holding great potential in brain disease imaging.Specific characteristics in brain environment and brain diseases(e.g.,marker proteins on the BBB,the pathogenic proteins in the neurodegenerative diseases or brain tumors,and the tumor and inflammatory microenvironment)provide opportunities for the functionalized nano-imaging agents to improve BBB crossing and disease targeting.Moreover,the versatile nano-imaging agents are endowed with therapeutic agents to facilitate the theranostics of brain diseases.Here,we summarized the common materials and imaging techniques of nano-imaging agents and their imaging treatment applications.We discussed their BBB penetration,environmental response for disease targeting,and therapeutic effects.We also provided insights on the advantages,challenges,and application of nano-imaging agents in detecting and treating brain diseases such as neurodegenerative diseases,brain tumors,stroke,and traumatic brain injury.These discussions will help develop nano-imaging agents-based theranostic platforms for the precise diagnosis and treatment of brain diseases.

Performance analysis of ghost imaging lidar in background light environment

The effect of background light on the imaging quality of three typical ghost imaging(GI) lidar systems(namely narrow pulsed GI lidar, heterodyne GI lidar, and pulse-compression GI lidar via coherent detection) is investigated. By computing the signal-to-noise ratio(SNR) of fluctuation-correlation GI, our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar via coherent detection has the strongest capacity against background light, whereas the reconstruction quality of narrow pulsed GI lidar is the most vulnerable to background light. The relationship between the peak SNR of the reconstruction image andσ(namely, the signal power to background power ratio) for the three GI lidar systems is also presented, and theresults accord with the curve of SNR-σ.

Recent advances in engineering iron oxide nanoparticles for effective magnetic resonance imaging

Iron oxide nanoparticle(IONP)with unique magnetic property and high biocompatibility have been widely used as magnetic resonance imaging(MRI)contrast agent(CA)for long time.However,a review which comprehensively summarizes the recent development of IONP as traditional T_(2) CA and its new application for different modality of MRI,such as T_(1) imaging,simultaneous T_(2)/T_(1) or MRI/other imaging modality,and as environment responsive CA is rare.This review starts with an investigation of direction on the development of high-performance MRI CA in both T_(2) and T_(1) modal based on quantum mechanical outer sphere and Solomon-Bloembergen-Morgan(SBM)theory.Recent rational attempts to increase the MRI contrast of IONP by adjusting the key parameters,including magnetization,size,effective radius,inhomogeneity of surrounding generated magnetic field,crystal phase,coordination number of water,electronic relaxation time,and surface modification are summarized.Besides the strategies to improve r2 or r1 values,strategies to increase the in vivo contrast efficiency of IONP have been reviewed from three different aspects,those are introducing second imaging modality to increase the imaging accuracy,endowing IONP with environment response capacity to elevate the signal difference between lesion and normal tissue,and optimizing the interface structure to improve the accumulation amount of IONP in lesion.This detailed review provides a deep understanding of recent researches on the development of high-performance IONP based MRI CAs.It is hoped to trigger deep thinking for design of next generation MRI CAs for early and accurate diagnosis.