Rox-DNA Functionalized Silicon Nanodots for Ratiometric Detection of Mercury Ions in Live Cells

Abstract

A ratiometric fluorescent sensor for mercury ions (Hg) has been constructed via covalent functionalization of silicon nanodot (SiND) with Hg-specific 6-carboxy-X-rhodamine (Rox)-tagged DNA. For the Rox-DNA functionalized SiND, the red fluorescence of Rox can be quenched by the blue-emitting SiND in the presence of Hg due to structural change in DNA, which serves as the response signal. Meawhile, the fluorescence of SiND is insensitive to Hg and acts as the reference signal. The wavelength difference in the optimal emission peak is as large as 190 nm between SiND (422 nm) and Rox (612 nm), which can efficaciously exclude the interference of the two emission peaks, and facilitates dual-color visualization of Hg ions. The biofunctionalization of SiND improves the acid-base stability of SiND significantly, which is favorable for its application in the intracellular environment. Accordingly, a sensitive, simple, precise and rapid method for tracing Hg was proposed. The limit of detection and precision of this method for Hg was 9.2 nM and 8.8% (50 nM, n = 7), respectively. The increase of Hg concentration in the range of 10-1500 nM was in accordance with linearly increase of the I/ I ratio. As for practical application, the recoveries in spiked human urine and serum samples were in the range of 81-107%. Moreover, this fluorescent nanosensor was utilized to the ratiometric detection of Hg in HeLa cells.

Nanomaterial-Based Dual-Emission Ratiometric Fluorescent Sensors for Biosensing and Cell Imaging

“…Our group demonstrated that water-soluble SiNDs can be easily prepared at gram scale by the hydrothermal method [ 20 , 49 ]. Then a series of SiNDs-based ratiometric biosensors were constructed for sensing pH, mucin 1, Hg 2+ , DNA, and dipicolinic acid in human serums or the cellular environment [ 20 , 21 , 22 , 23 , 50 , 51 ]. For example, we developed a ratiometric fluorescent Hg 2+ sensor by covalent modification of SiND with Hg 2+ -specific 6-carboxyX-rhodamine (Rox)-tagged DNA ( Figure 3 A).…”

“… ( A ) Schematic presentation of the preparation of SiND-DNA-Rox and its application for ratiometric detection of Hg 2+ . Reproduced from [ 23 ], with permission from the American Chemical Society, 2018. ( B ) ( a ) Schematic of Eu@SiNRs sensor, ( b ) TEM image of Eu@SiNRs, ( c ) fluorescence spectra of Eu@SiNRs in PBS buffers with different pH values under 405 nm excitation, ( d ) a Eu@SiNRs-based pH sensor for ratiometric measurements of cytoplasmic pH in live cells.…”

“…Additionally, organic dyes are usually encapsulated with nanomaterials to improve their optical stability and biocompatibility [ 19 ]. In addition, surface functionalization of the nanomaterials can make them targeted for specific analytes, cells, or even subcellular organelles, thus resulting in effective biosensing and intracellular imaging [ 20 , 21 , 22 , 23 ]. Typically, the fabrication of ratiometric fluorescent bionanosensors starts with the preparation of the nanomaterials in one of the following ways: bottom up, top down, or a combination of bottom up and top down that is followed by surface-chemistry modification.…”

Orange-Emissive Sulfur-Doped Organosilica Nanodots for Metal Ion/Glutathione Detection and Normal/Cancer Cell Identification

“…18,19 In addition, Hg poisoning in living organisms is still a hot issue of global concern, as Hg 2+ can easily penetrate biological membranes and cause toxicity. 20,21 Considering that various metal-sensing platforms can only detect limited types of metal ions, 22−24 it is desirable to develop a multifunctional sensing platform for achieving the simultaneous and efficient detection of different types of metal ions to well meet the increased requests of clinical diagnosis and sanitation monitoring systems.…”

“…In recent years, developing smart sensors with versatile sensing capabilities and high sensitivity has drawn much interest from the biosensing community. − Various sensing platforms have been developed for the efficient detection of different metal elements, which may have the positive and/or negative effects on human bodies. Specifically, Fe and Cu are the essential elements of the human body for numerous physiological and pathological functions. − The Bi element has been extensively used for radiotherapeutic, antibacterial, antiulcer, and anti-human immunodeficiency virus (anti-HIV) treatments. , However, abnormal contents of Fe, Cu, or Bi usually cause various diseases, such as anemia, hepatitis, Wilson’s/Alzheimer’s/Parkinson’s disease, or even cancer. − For Ag, its excessive content in the body will lead to severe skin problems, stomach pain, nervous system damage, and even death. − For Pd, the excess intake of this element will badly affect various cellular processes and result in severe physiological disorders. , In addition, Hg poisoning in living organisms is still a hot issue of global concern, as Hg 2+ can easily penetrate biological membranes and cause toxicity. , Considering that various metal-sensing platforms can only detect limited types of metal ions, − it is desirable to develop a multifunctional sensing platform for achieving the simultaneous and efficient detection of different types of metal ions to well meet the increased requests of clinical diagnosis and sanitation monitoring systems.…”