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Fluorescence and phosphorescence are known as two kinds of fundamental optical signals, which have been used for myriad applications. Of particular note, simultaneous activation of stable fluorescence and long-lived room temperature phosphorescence (RTP) emission in aqueous phase remains a big challenge up to present. Herein, we prepare a kind of zinc-doped silica nanospheres (Zn@SiNSs) with fluorescence and RTP properties through a facile hydrothermal synthetic strategy. For the as-prepared Zn@SiNSs, the recombination of electrons and holes in defects and defect-stabilized excitons derived from oxygen vacancy/C=N bonds lead to the production of stable fluorescence and long-lived RTP (emission lasting for ~9 s, quantum yield (QY): ~33.6%, RTP lifetime: ~236 ms). In addition, the internal Si-O bonded networks and hydrophilic surface in Zn@SiNSs can reduce nonradiative decay to form self-protective RTP, and also provide high water solubility, excellent pH- and photo-stability.

The production of bimetallic nanoparticles with ultrasmall sizes is the constant pursuit in chemistry and materials science because of their promising applications in catalysis, electronics and sensing. Here we report ambient-temperature preparation of bimetallic NPs with tunable size and composition using microfluidic-controlled co-reduction of two metal precursors on silicon surface. Instead of free diffusion of metal ions in bulk system, microfluidic flow could well control the local ions concentration, thus leading to homogenous and controllable reduction rate among different nucleation sites. By controlling precursor concentration, flow rate and reaction time, we rationally design a series of bimetallic NPs including Ag-Cu, Ag-Pd, Cu-Pt, Cu-Pd and Pt-Pd NPs with ultrasmall sizes (∼ 3.0 nm), tight size distributions (relative standard deviation (RSD) < 21%), clean surface, and homogenous elemental compositions among particles (standard deviation (SD) of weight ratios < 3.5%). This approach provides a facile, green and scalable method toward the synthesis of diverse bimetallic NPs with excellent activity.

Pre-chirp managed amplification (PCMA) allows the generation of optical pulses with a duration well below 100 fs. However, the pulse peak power is limited to 30 times improvement in both pulse energy and peak power compared with current Yb-fiber PCMA systems.

Background Ex vivo and in vivo detection and imaging of adenosine triphosphate (ATP) is critically important for the diagnosis and treatment of diseases, which still remains challenges up to present. Results We herein demonstrate that ATP could be fluorescently detected and imaged ex vivo and in vivo. In particular, we fabricate a kind of fluorescent ATP probes, which are made of titanium carbide (TC) nanosheets modified with the ROX-tagged ATP-aptamer (TC/Apt). In the constructed TC/Apt, TC shows superior quenching efficiency against ROX (e.g., ~ 97%). While in the presence of ATP, ROX-tagged aptamer is released from TC surface, leading to the recovery of fluorescence of ROX under the 545-nm excitation. Consequently, a wide dynamic range from 1 μM to 1.5 mM ATP and a high sensitivity with a limit of detection (LOD) down to 0.2 μM ATP can be readily achieved by the prepared TC/Apt. We further demonstrate that the as-prepared TC/Apt probe is feasible for accurate discrimination of ATP in different samples including living cells, body fluids (e.g., mouse serum, mouse urine and human serum) and mouse tumor models. Conclusions Fluorescence detection and imaging of ATP could be readily achieved in living cells, body fluids (e.g., urine and serum), as well as mouse tumor model through a new kind of fluorescent ATP nanoprobes, offering new powerful tools for the treatment of diseases related to abnormal fluctuation of ATP concentration.

We demonstrate an Yb-fiber based pre-chirp managed amplification system that emits 50-MHz, 47-fs pulses with 101.2-W average power. Using chirped mirrors as a compressor, we achieve 98% throughput efficiency.

We incorporate pre-chirp management into SPM enabled spectral selection to improve efficiency and reshape unfavorable input flat-top pulses. This new technique produces megawatt-level femtosecond pulses tunable in the wavelength range of 0.86-1.3 µm.

MicroRNAs (miRNAs) are promising biomarkers for the early diagnosis of breast cancer. Yet, simultaneous achievement of rapid, sensitive and accurate detection of diverse miRNAs in clinical samples is still challenging due to the low abundance of miRNAs and the complex procedures of RNA extraction and separation. Herein, we develop an innovative three-dimensional (3D) surface-enhanced Raman scattering (SERS) holography sensing strategy for rapid, sensitive and multiplexed detection of human breast cancer-associated miRNAs. To establish a proof of concept, nine kinds of human breast cancer-associated miRNAs are isothermally amplified by Exonuclease (Exo) III enzyme, and the products could be spatially separated to corresponding sensing region on silicon SERS substrates. Each region has been modified with corresponding hairpin DNA probes, which are used to identify and quantify the miRNAs. Different DNA probes are labeled with different Raman reporters, which serve as “SERS tags” to incorporate spectroscopic information into computer-generated 3D SERS hologram within ~9 min. We demonstrate that 3D SERS holography chip not only achieves an ultrahigh sensitivity down to ~1 aM but also feature a high correlation with RT-qPCR in the detection of nine miRNAs in 30 clinical serum samples. This work provides a feasible tool to improve the diagnosis of breast cancer.

In this manuscript, we demonstrate that the in situ growth of fluorescent silicon (Si) nanomaterials is stimulated when organosilicane molecules interact with different green teas, producing multifunctional Si nanomaterials with controllable zero- (e.g., nanoparticles), two- (e.g., nanosheets), and three- (e.g., nanospheres) dimensional nanostructures. Such green tea-originated Si nanomaterials (GTSN) exhibit strong fluorescence (quantum yield: ∼19-30%) coupled with ultrahigh photostability, as well as intrinsic anti-cancer activity with high specificity (e.g., the GTSN can accurately kill various cancer cells, rather than normal cells). Taking advantage of these unique merits, we further performed systematic in vitro and in vivo experiments to interrogate the mechanism of the green tea- and GTSN-related cancer prevention. Typically, we found that the GTSN entered the cell nuclei and induced cell apoptosis/death of cancer cells. The prepared GTSN were observed in vivo to accumulate in the tumour tissues after 14-d post-injection, leading to an efficient inhibition of tumour growth. Our results open new avenues for designing novel multifunctional and side-effect-free Si nanomaterials with controllable structures.

Herein, we present a dual-amplification sensing strategy-based surface-enhanced Raman scattering (SERS) chip, which combines rolling circle amplification (RCA) and polyadenine (PolyA) assembly for sensitive and reproducible determination of the activity of M.SssI, a cytosine-guanine dinucleotide (CpG) methyltransferase (MTase). Typically, in the presence of M.SssI, RCA process is triggered, resulting in long, single-stranded DNA (ssDNA) fragments that are hybridized with thousands of Raman reporters of Cy3. Afterward, the resultant ssDNA fragments are conjugated to SERS-active substrates made of silver core-gold satellite nanocomposites-modified silicon wafer (Ag-Au NPs@Si), with the SERS enhancement factor of ∼5 × 106. The core-satellite nanostructures are assembled relied on the strong affinity of PolyA toward gold/silver surface. Of particular significance, the developed SERS chip displays an ultrahigh sensitivity with a low limit of detection (LOD) of 2.8 × 10-3 U/mL, which is around 2 orders of magnitude higher than most reported methods. In addition, the constructed chip features a broad detection range covering from 0.05 to 50 U/mL. Besides for the ultrahigh sensitivity and broad dynamic range, the chip also features good reproducibility (e.g., the relative standard deviation (RSD) is less than ∼12%). Taking advantages of these merits, the developed chip is feasible for accurate discrimination of M.SssI with various concentrations spiked in human serum samples with good recoveries ranging from 99.6% to 107%.

Self-phase-modulation-enabled spectral selection (SESS) allows generation of widely tunable femtosecond pulses. We propose pre-chirp managed SESS, in which the excitation pulse is properly pre-chirped to control the fiber-optic nonlinear spectral broadening and hence generate separated spectral lobes—a feature demanded by SESS. Besides offering improved efficiency compared with conventional energy-tuned SESS, this new method is able to reshape an input pulse of unwanted shape into a bell-shaped pulse that is desired for implementing SESS. The excellent energy scalability of pre-chirp managed SESS can produce megawatt-level femtosecond pulses widely tunable in the wavelength range of 0.86–1.3 µm. Such a powerful source is well suited to drive multiphoton microscopy to achieve deep-tissue imaging.