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Super-resolution imaging using nano-bells
摘要： In this paper we demonstrate a new scheme for optical super-resolution, inspired, in-part, by PALM and STORM. In this scheme each object in the field of view is tagged with a signal that allows them to be detected separately. By doing this we can identify and locate each object separately with significantly higher resolution than the diffraction limit. We demonstrate this by imaging nanoparticles significantly smaller than the optical resolution limit. In this case the “tag” we have used is the frequency of vibration of nanoscale “bells” made of metallic nanoparticles whose acoustic vibrational frequency is in the multi-GHz range. Since the vibration of the particles can be easily excited and detected and the frequency is directly related to the particle size, we can separate the signals from many particles of sufficiently different sizes even though they are smaller than, and separated by less than, the optical resolution limit. Using this scheme we have been able to localise the nanoparticle position with a precision of ~3 nm. This has many potential advantages - such nanoparticles are easily inserted into cells and well tolerated, the particles do not bleach and can be produced easily with very dispersed sizes. We estimate that 50 or more different particles (or frequency channels) can be accessed in each optical point spread function using the vibrational frequencies of gold nanospheres. However, many more channels may be accessed using more complex structures (such as nanorods) and detection techniques (for instance using polarization or wavelength selective detection) opening up this technique as a generalized method of achieving super-optical resolution imaging.
关键词： optical resolution limit,acoustic vibrational frequency,nanoparticles,nano-bells,super-resolution imaging
更新于2025-09-23 15:21:21
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Flexibly adjustable depth-of-focus photoacoustic microscopy with spatial light modulation
摘要： Through focusing the excitation laser, optical-resolution photoacoustic microscopy (OR-PAM) is capable of measuring optical absorption properties down to micrometer-scale lateral resolution within biological tissues. The focused Gaussian beam routinely employed in the OR-PAM setups is inadequate for acquiring the volumetric images of biological specimens with thickness from tens micrometers to millimeter without scanning in depth because of the inconsistent lateral resolution along the depth direction due to its short depth of focus (DoF). Here, we integrate a spatial light modulator (SLM) into the optical path of an OR-PAM for realizing the flexibly adjustable DoF. By simply switching the phase patterns assigned onto the SLM interface, three representative illumination beams are produced, including conventional short-DoF Gaussian beam (GB), needle-like Bessel beam (BB), and extended depth-of-focus beam (EDFB). These modulations can be well realized based on the extended Nijboer-Zernike theory. The photoacoustic excitations show variable DoFs ranging from hundreds of micrometers (GB and BB) up to 1.38 mm (EDFB) but a consistent lateral resolution of (cid:2)3.5 lm. The proposed method is confirmed by volumetric imaging of multiple tungsten fibers positioned at different depths.
关键词： spatial light modulation,photoacoustic microscopy,depth-of-focus,extended depth-of-focus beam,Bessel beam,optical-resolution
更新于2025-09-23 15:21:21
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Quantitative analysis on <i>in vivo</i> tumor-microvascular images from optical-resolution photoacoustic microscopy
摘要： Optical-resolution photoacoustic microscopy (OR-PAM) has been shown to be an excellent imaging modality for monitoring and study of tumor microvasculature. However, previous studies focused mainly on the normal tissues and did not quantify the tumor microvasculature. In this study, we present an in vivo OR-PAM imaging of the melanomas and hepatoma implanted in the mouse ear. We quantify the vessel growth by extracting the skeletons of both dense and thin branches of the tumor microvasculature obtained by Hessian matrix enhancement followed by improved two-step multistencils fast marching method. Compared to the previous methods of using OR-PAM for normal tissues, our method was more effective in extracting the binary vascular network in the tumor images and in obtaining the complete and continuous microvascular skeleton maps. Our demonstration of using OR-PAM in improving microvasculature of tumors and quantification of tumor growth would push deep this technology for the early diagnosis and treatment of cancers.
关键词： photoacoustic imaging,tumor neovascular network,quantitative analysis,optical-resolution photoacoustic microscopy
更新于2025-09-19 17:15:36
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[1]Benzothiophene-Fused Chiral Spiro Polycyclic Aromatic Compounds: Optical Resolution, Functionalization, and Optical Properties
摘要： Spiro polycyclic aromatic compounds have been known as rigid chiral scaffolds. In order to extend their applications, an efficient preparation route to enantiopure derivatives is highly required. Here, we design 10,10′-spirobi[indeno[1,2-b][1]benzothiophene]-7,7′-diol to achieve efficient optical resolution. The compound was successfully synthesized and resolved by chiral HPLC on a semipreparative scale. The absolute configuration of its enantiopure isomer was determined through single crystal X-ray structure analysis of its derivative. The compound was also transformed into its derivatives with donor–acceptor (D–A) type systems. The obtained chiral D–A type molecules exhibited remarkable solvent-dependence fluorescence and were found to be solvent-sensitive circularly polarized luminescent materials. These results clearly demonstrated the utility of 10,10′-spirobi[indeno[1,2-b][1]benzothiophene]-7,7′-diol as a versatile building block for chiral spiro polycyclic aromatic compounds.
关键词： donor–acceptor (D–A) type systems,circularly polarized luminescent materials,optical resolution,Spiro polycyclic aromatic compounds,chiral HPLC
更新于2025-09-09 09:28:46
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Advances in photonic quantum sensing
摘要： Quantum sensing has become a broad field. It is generally related with the idea of using quantum resources to boost the performance of a number of practical tasks, including the radar-like detection of faint objects, the readout of information from optical memories, and the optical resolution of extremely close point-like sources. Here, we first focus on the basic tools behind quantum sensing, discussing the most recent and general formulations for the problems of quantum parameter estimation and hypothesis testing. With this basic background in hand, we then review emerging applications of quantum sensing in the photonic regime both from a theoretical and experimental point of view. Besides the state of the art, we also discuss open problems and potential next steps.
关键词： quantum hypothesis testing,quantum parameter estimation,photonic quantum sensing,optical resolution,quantum reading,quantum sensing,quantum illumination
更新于2025-09-09 09:28:46
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Synthesis, structural characterization and photophysical properties of 7-cyanohexahelicene
摘要： 7-Cyanoexahelicene has been prepared in racemic form through a short photochemical synthetic approach and its enantiomeric separation was studied and allowed to obtain (P)- and (M)-enantiomers in 100% ee and > 98.5% ee, respectively. The optical rotatory dispersion and electronic circular dichroism (ECD) spectra of the resolved ones were measured. Other optical properties such as UV and photoluminescence as well as the electrochemical behavior were also examined in solutions.
关键词： Optical resolution,Chirality,Couplings,Photophysical properties,gap energy,Helicenes,Photooxidation
更新于2025-09-04 15:30:14