Due to their unique properties, rare-earth doped upconversion luminescence (UCL) nanomaterials are of considerable scientific interest. Meanwhile, alkaline-earth sulfide materials based on a completely different electron trapping (ET) mechanism demonstrate extremely high UCL efficiencies, which are several dozens of times more than those of conventional fluoride UCL nanomaterials. However, the large particle size, easy hydrolysis, and difficulty in achieving uniform dispersion have precluded bioassay applications. Herein, we have synthesized super-bright Eu,Sm,Mn-doped CaS nanoparticles of ∼30 nm average particle size using a reverse microemulsion technique. The UCL quantum yield was up to nearly 60%. Modification of the nanoparticles with an organic layer allows their stable dispersion throughout aqueous solutions without significant loss of the fluorescence intensity. We demonstrate the application of the novel UCL materials to latent fingerprint detection, deep tissue imaging, and in vivo bioimaging.
Eu,Sm,Mn-doped CaS (ESM-CaS) nanoparticles demonstrate a remarkable upconversion luminescence (UCL) efficiency with a quantum yield of nearly 60%, enabling many new applications and devices. We describe an ESM-CaS nanoparticle-based paper test strip for one-shot quantitative measurement of sulfite concentration using a smartphone-based reader. The integrated UCL-based sulfite detection system features high sensitivity and facile operation without the need for separation and pretreatment. Moreover, the design principles are general in nature and so can be tailored for the detection and quantification of a variety of other analytes.
The multiple-metal-nanoparticle tagging
strategy has generally
been applied to the multiplexed detection of multiple analytes of
interest such as microRNAs (miRNAs). Herein, it was used for the first
time to improve both the specificity and sensitivity of a novel mass
spectroscopic platform for miRNA detection. The mass spectroscopic
platform was developed through the integration of the ligation reaction,
hybridization chain reaction amplification, multiple-metal-nanoparticle
tagging, and inductively coupled plasma mass spectrometry. The high
specificity resulted from the adoption of the ligation reaction is
further enhanced by the multiple-metal-nanoparticle tagging strategy.
The combination of hybridization chain reaction amplification and
metal nanoparticle tagging endows the proposed platform with the feature
of high sensitivity. The proposed mass spectrometric platform achieved
quite satisfactory quantitative results for Let-7a in real-world cell
line samples with accuracy comparable to that of the real-time quantitative
reverse-transcriptase polymerase chain reaction method. Its limit
of detection and limit of quantification for Let-7a were experimentally
determined to be about 0.5 and 10 fM, respectively. Furthermore, due
to the unique way of utilizing the multiple-metal-nanoparticle tagging
strategy, the proposed platform can unambiguously discriminate between
the target miRNA and nontarget ones with single-nucleotide polymorphisms
based on their response patterns defined by the relative mass spectral
intensities among the multiple tagged metal elements and can also
provide location information of the mismatched bases. Its unique advantages
over conventional miRNA detection methods make the proposed platform
a promising and alternative tool in the fields of clinical diagnosis
and biomedical research.
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