Recently, the development of new fluorescent probes for the ratiometric detection of target objects inside living cells has received great attention. Normally, the preparation, modification as well as conjugation procedures of these probes are complicated. On this basis, great efforts have been paid to establish convenient method for the preparation of dual emissive nanosensor. In this work, a functional dual emissive carbon dots (dCDs) was prepared by a one-pot hydrothermal carbonization method. The dCDs exhibits two distinctive fluorescence emission peaks at 440 and 624 nm with the excitation at 380 nm. Different from the commonly reported dCDs, this probe exhibited an interesting wavelength dependent dual responsive functionality toward lysine (440 nm) and pH (624 nm), enabling the ratiometric detection of these two targets. The quantitative analysis displayed that a linear range of 0.5-260 μM with a detection limit of 94 nM toward lysine and the differentiation of pH variation from 1.5 to 5.0 could be readily realized in a ratiometric strategy, which was not reported before with other carbon dots (CDs) as the probe. Furthermore, because of the low cytotoxicity, good optical and colloidal stability, and excellent wavelength dependent sensitivity and selectivity toward lysine and pH, this probe was successfully applied to monitor the dynamic variation of lysine and pH in cellular systems, demonstrating the promising applicability for biosensing in the future.
Photodynamic
therapy (PDT) has attracted great attention as an
alternative tumor treatment method. Unfortunately, it suffers from
some limitations like poor targeting capability and insufficient therapeutic
efficiency caused by tumor hypoxia. In this work, we introduce a novel
O2-evolving PDT nanoparticle for homologous cancer cell
targeting as well as dual-mode imaging [i.e., magnetic resonance imaging
(MRI) and fluorescence imaging]. Specifically, the nanostructure consists
of a MnO2 nanosheet-coated metal–organic framework
core and cancer cell membrane shell (defined as CM-MMNPs). The MnO2 layer displays H+ and H2O2 responsiveness, which can produce O2 to enhance O2-mediated singlet oxygen (1O2) generation
for PDT. Moreover, the resulted Mn2+ can also be used as
an optimal MRI contrast agent. The introduction of cell membrane and
membrane proteins endow the CM-MMNPs with good stability and integrity
in the process of cellular endocytosis, as well as strong homologous
cell-targeting ability. This multifunctional nanoparticle has the
potential to overcome the hypoxia of cancer cells in PDT, and provides
a new paradigm for tumor targeting, detection, and therapy, which
is promising for biomedical applications in the future.
Prostate-specific antigen (PSA) is an intercellular glycoprotein produced primarily by the prostate gland, which is commonly chosen as the initial target for the early diagnosis of prostate cancer. In this work, we demonstrate a simple yet sensitive sandwich-type single-particle enumeration (SPE) immunoassay for the quantitative detection of PSA in a flow chamber. The design is based on the luminescence resonance energy transfer (LRET) between upconversion nanoparticles (UCNPs) and gold nanoparticles (GNPs). The carboxyl group-functionalized UCNPs are conjugated with anti-PSA detection antibodies (Ab) and serve as the luminescence energy donor, while GNPs are modified with anti-PSA capture antibodies (Ab) and act as the energy acceptor. In the presence of target antigen (i.e., PSA), the specific immnuoreaction brings the donor and acceptor into close proximity, resulting in quenched luminescence. Through statistical counting of the target-dependent fluorescent particles on the glass slide surface, the quantity of antigens in the solution is accurately determined. The dynamic range for PSA detection in Tris-buffered saline (TBS) is 0-500 pM and the limit-of-detection (LOD) is 1.0 pM, which is much lower than the cutoff level in patients' serum samples. In the serum sample assay, comparable LOD was also achieved (i.e., 2.3 pM). As a consequence, this method will find promising applications for the selective detection of cancer biomarkers in clinical diagnosis.
Artificial aquaporins are synthetic
molecules that mimic the structure
and function of natural aquaporins (AQPs) in cell membranes. The development
of artificial aquaporins would provide an alternative strategy for
treatment of AQP-related diseases. In this report, an artificial aquaporin
has been constructed from an amino-terminated tubular molecule, which
operates in a unimolecular mechanism. The artificial channel can work
in cell membranes with high water permeability and selectivity rivaling
those of AQPs. Importantly, the channel can restore wound healing
of the cells that contain function-lost AQPs.
In this work, the distinct catalytic properties of a single gold nanoparticle (GNP) after symmetry breaking were disclosed at the single-particle level for the first time.
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