Journal of Materials Chemistry B Editor's choice web collection: “Seeing the unseen updated: advances in bioimaging”
Xiaogang
Qu
Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China. E-mail: xqu@ciac.ac.cn
Abstract
Xiaogang Qu introduces a Journal of Materials Chemistry B Editor's choice web collection on advances in bioimaging (http://rsc.li/BioimagingAdvances).
 Xiaogang Qu |
Currently, materials for biology and medicine have been considered as an emerging focus and significant interest of researchers. This interest includes the rational design and synthesis of these materials, as well as their related usages in bioimaging, sensing, drug delivery, and disease therapy. Because of their excellent performance for tracking biological activity and detecting pathological processes, various novel fluorescent nanomaterials and activatable probes with high sensitivity, great selectivity, and admirable bio-compatibility have been successfully designed and developed with ideal outcomes. Within these, fluorescent probe-based platforms can monitor disease status, give accurate diagnosis and prognosis, as well as provide comprehensive statistical analysis.
Conventional organic dyes usually suffer from some intrinsic limitations including high resistance towards photo-bleaching, restricted photo-stability, and relatively short fluorescent lifetime. To overcome these shortcomings, numerous fluorescent nanomaterials based on novel inorganic components, organic components, and hybrid ones have exhibited their imaging abilities in the field of bioimaging and imaging-based detection. Over the years, various inorganic nanoprobes, such as semiconductor quantum dots, carbon quantum dots, silica nanodots, and rare earth-based nanomaterials, have been at the forefront of the most recent advances in bioimaging. In parallel, fluorescent nanoparticles with several chromophores integrated into one particle also show many advantages for bioimaging because of their better photophysical properties, amplification of fluorescent signals, and multifunctional potential.
From the viewpoints of the intrinsic nature, imaging mechanism, and biological usages of these fluorescent nanomaterials, some noteworthy issues may draw the attention of scientists and engineers along with the rapid development of nanotechnology and bioengineering. For instance, a series of carbon quantum dots (C-dots) have been believed to include good photo-stability, outstanding water solubility, as well as high sensitivity and selectivity towards target analytes. Recently, heteroatom-doped approaches and surface engineering methods have been used as efficient strategies to endow these C-dots with high performances in bioimaging. All these aspects of C-dots with admirable properties and related biological usages are summarized in review articles by Weijian Liu (DOI: 10.1039/c6tb00976j) and Quan Xu (DOI: 10.1039/c6tb02131j). Significantly, bovine serum albumin was used as the raw material to synthesize fluorescent N-doped C-dots with a high quantum yield for imaging human osteosarcoma U2OS cells (DOI: 10.1039/c6tb00519e). Moreover, a facile but efficient pyrolysis approach was reported to prepare Gd-encapsulated C-dots for dual-modal fluorescence/magnetic resonance bioimaging (DOI: 10.1039/c6tb02115h). All these investigations made with C-dots have indicated that nanoprobes based on carbon quantum dots can act as new tools for various functional bioimaging.
Since their discovery in the 1960s, upconversion (UC) materials and their luminescence mechanism have been the focus of many researchers. In particular, UC materials with strong luminescence in NIR to NIR/visible/UV have been extensively explored in biomedical diagnosis and therapies recently. For example, nanoprobes based on ZnMoO4:Tm3+,Yb3+,K+ with intense NIR to NIR UC luminescence were synthesized via a facile hydrothermal route. These nanoprobes were used for non-invasive visualization of deep tumors, which further opened the door to the possibility of achieving improved bioimaging using non-fluoride based UC nanoparticles (DOI: 10.1039/c6tb00965d). Moreover, some recent studies focused on the development of various novel UC nanomaterials and their related usages in bioimaging were nicely summarized in a review article by E. Hemmer (DOI: 10.1039/c7tb00403f).
Fluorescent organic nanoparticles based on organic dyes often suffer from quenching phenomena when they are dispersed in aqueous solutions or interact with cellular biomolecules. Recently, organic molecules with unique aggregated induced emission (AIE) features have provided effective nanoplatforms for bioimaging owing to their obvious enhancement in fluorescence at the aggregated state. For example, an efficient method has been developed to construct AIE-active fluorescent organic nanoparticles with pH response via a one-pot strategy which combined hydrophobic TPE-CHO, hydrophilic carbohydrate polymers, and ABBA (DOI: 10.1039/c6tb00776g). Moreover, Tang’s group reported several hybrid nanoparticles with AIE characteristics, and used them for nucleolus and mitochondria imaging with organelle-specific emission (DOIs: 10.1039/c6tb00319b, 10.1039/c6tb01466f).
The tremendous scientific interest generated by the rational synthesis and bioimaging usages of various novel fluorescent materials have been further extended to the intracellular detection of different inflammatory factors by using these agents as stimuli-responsive probes. Their high potential for related biomedical detection via these fluorescent materials is clearly illustrated in a number of articles. A novel pyrano[3,2-c]julolidin-2-one based fluorescent molecular rotor has been designed for selective ratiometric detection, quantification, and imaging of intracellular Hg2+ ions (DOI: 10.1039/c6tb01413e). Jianhua Ma has reported a NIR fluorescent chemodosimeter, named as Cy–Sn, displaying a turn-on fluorescence after reaction with H2Sn, which can be used to monitor endogenous hydrogen polysulfides via the cystathionine g-lyase enzymatic pathway (DOI: 10.1039/c7tb00098g). In addition, several kinds of fluorescence resonance energy transfer platforms have been well designed and developed to obviously visualize exogenous and endogenous hypochlorous acid in living cells (DOIs: 10.1039/c6tb01085g, 10.1039/c6tb01992g).
In summary, bioimaging by using fluorescent probes has made significant breakthroughs in recent years, and many interesting results have been published in this exciting field. This Editor's choice web collection (http://rsc.li/BioimagingAdvances) entitled “Seeing the unseen updated: advances in bioimaging” highlights Journal of Materials Chemistry B's recent outstanding papers in functional materials-based bioimaging. It is the first in a two-part online collection focused on bioimaging and biosensors. Journal of Materials Chemistry B is an interdisciplinary journal, covering all aspects of the production, properties or applications of materials for healthcare and biomedicine, materials at the biointerface, biomimetics and bio-inspired or natural materials.
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