Chen Chaohao, Liu Baolei, Liu Yongtao, Liao Jiayan, Shan Xuchen, Wang Fan, Jin Dayong
Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia.
School of Electrical and Data Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, 2007, Australia.
Adv Mater. 2021 Jun;33(23):e2008847. doi: 10.1002/adma.202008847. Epub 2021 Apr 17.
Point spread function (PSF) engineering by an emitter's response can code higher-spatial-frequency information of an image for microscopy to achieve super-resolution. However, complexed excitation optics or repetitive scans are needed, which explains the issues of low speed, poor stability, and operational complexity associated with the current laser scanning microscopy approaches. Here, the diverse emission responses of upconversion nanoparticles (UCNPs) are reported for super-resolution nanoscopy to improve the imaging quality and speed. The method only needs a doughnut-shaped scanning excitation beam at an appropriate power density. By collecting the four-photon emission of single UCNPs, the high-frequency information of a super-resolution image can be resolved through the doughnut-emission PSF. Meanwhile, the two-photon state of the same nanoparticle is oversaturated, so that the complementary lower-frequency information of the super-resolution image can be simultaneously collected by the Gaussian-like emission PSF. This leads to a method of Fourier-domain heterochromatic fusion, which allows the extended capability of the engineered PSFs to cover both low- and high-frequency information to yield optimized image quality. This approach achieves a spatial resolution of 40 nm, 1/24th of the excitation wavelength. This work suggests a new scope for developing nonlinear multi-color emitting probes in super-resolution nanoscopy.
通过发射器响应进行点扩散函数（PSF）工程可以对显微镜图像的更高空间频率信息进行编码，以实现超分辨率。然而，这需要复杂的激发光学器件或重复扫描，这解释了当前激光扫描显微镜方法存在的速度慢、稳定性差和操作复杂等问题。在此，报道了上转换纳米粒子（UCNP）的多种发射响应用于超分辨率纳米显微镜，以提高成像质量和速度。该方法仅需要具有适当功率密度的环形扫描激发光束。通过收集单个UCNP的四光子发射，可以通过环形发射PSF解析超分辨率图像的高频信息。同时，同一纳米粒子的双光子态过饱和，因此可以通过类高斯发射PSF同时收集超分辨率图像的互补低频信息。这导致了一种傅里叶域异色融合方法，该方法允许工程化PSF的扩展能力覆盖低频和高频信息，以产生优化的图像质量。这种方法实现了40nm的空间分辨率，为激发波长的1/24。这项工作为在超分辨率纳米显微镜中开发非线性多色发射探针开辟了新的领域。
