One-Pot Microwave Synthesis of Water-Dispersible, High Fluorescence Silicon Nanoparticles and Their Imaging Applications in Vitro and in Vivo

Multiplex Photoluminescent Silicon Nanoprobe for Diagnostic Bioimaging and Intracellular Analysis

Herein, a label-free multiplex photoluminescent silicon nanoprobe (PLSN-probe) is introduced as a potential substitute for quantum dots (QDs) in bioimaging. An inherently non-photoluminescent silicon substrate is altered to create the PLSN-probe, to overcome the major drawbacks of presently available QDs. Additionally, crystallinity alterations of the multiplane crystalline PLSN-probes lead to broad absorption and multiplex fluorescence emissions, which are attributed to the simultaneous existence of multiple crystal planes. The PLSN-probe not only demonstrates unique optical properties that can be exploited for bioimaging but also exhibits cell-selective uptake that allows the differentiation and diagnosis of HeLa and fibroblast cells. Moreover, multiplex emissions of the PLSN-probe illuminate different organelles such as the nucleus, nucleolemma, and cytoskeleton, depending on size-based preferential uptake by the cell organs. This in vitro study reveals that cancerous HeLa cells have a higher propensity for taking up the PLSN-probe compared to fibroblast cells, allowing the diagnosis of cancerous HeLa cells. Additionally, the fluorescence intensity per unit area of the cell is found to be a reliable means for distinguishing between dead and healthy cells. It is anticipated that the multifunctionality of the PLSN-probes will lead to better insight into the use of such probes for bioimaging and diagnosis applications.

Silicon nanoparticles coated with an epitope-imprinted polymer for fluorometric determination of cytochrome c

The authors describe a composite consisting of silicon nanoparticles that were first coated with SiO₂ and then with a molecularly imprinted polymer (SiNP@SiO₂@MIP). The MIP was generated by dual epitope imprinting such that it can recognize cytochrome c (Cyt c). The MIP on the NPs was prepared from the functional monomer zinc(II) acrylate (ZnA), the crosslinker ethylene glycol dimethacrylate and the initiator 2,2'-azoisobutyronitrile. Dual epitope templates for Cyt c included (a) a C-terminal nonapeptide (AYLKKATNE), and (b) an N-terminal nonapeptide (GDVEKGKKI). The chelation between Zn(II) of ZnA and the amino groups or hydroxy groups of the template nonapeptides warrants good recognition and capture of Cyt c. The fluorescence originating from SiNPs has excitation/emission peaks at 360/480 nm and is quenched by Cyt c in the 0.50-40.0 μM concentration range. The correlation coefficient for the calibration plot of the imprinted NPs is 0.9937. The detection limit is 0.32 ± 0.01 μM, the precisions of six replicate detections at levels of 0.5, 20 and 40 μM Cyt c are 3.2, 2.7 and 2.8%, respectively, and the imprinting factor is 2.43. Compared to single epitope template imprinting, dual epitope imprinting results in improved selectivity. The imprinted nanoparticles can discriminate Cyt c even if one amino acid is mismatched. The method was applied to the determination of Cyt c in spiked diluted human serum and gave recoveries between 94.0 and 107.5%. Graphical Abstract A fluorescent material of the architecture silicon nanoparticle@SiO₂@molecularly imprinted polymer (SiNP@SiO₂@MIP) was fabricated by dual epitope imprinting and a metal-chelating method. The chelation between Zn(II) of the functional monomer zinc(II) acrylate and the amino groups or hydroxy groups of template warrants that the material recognizes and captures cytochrome c well, and this results in fluorescence quenching.

Single molecule localization imaging of exosomes using blinking silicon quantum dots

Discovering new fluorophores, which are suitable for single molecule localization microscopy (SMLM) is important for promoting the applications of SMLM in biological or material sciences. Here, we found that silicon quantum dots (Si QDs) possess a fluorescence blinking behavior, making them an excellent candidate for SMLM. The Si QDs are fabricated using a facile microwave-assisted method. Blinking of Si QDs is confirmed by single particle fluorescence measurement and the spatial resolution achieved is about 30 nm. To explore the potential application of Si QDs as the nanoprobes for SMLM imaging, cell derived exosomes are chosen as the object owing to their small size (50-100 nm in diameter). Since CD63 is commonly presented on the membrane of exosomes, CD63 aptamers are attached to the surface of Si QDs to form nanoprobes which can specifically recognize exosomes. SMLM imaging shows that Si QDs based nanoprobes can indeed realize super resolved optical imaging of exosomes. More importantly, blinking of Si QDs is observed in water or PBS buffer with no need for special imaging buffers. Besides, considering that silicon is highly biocompatible, Si QDs should have minimal cytotoxicity. These features make Si QDs quite suitable for SMLM applications especially for live cell imaging.

One-pot hydrothermal preparation of gadolinium-doped silicon nanoparticles as a dual-modal probe for multicolor fluorescence and magnetic resonance imaging

One-pot hydrothermal preparation of gadolinium-doped silicon nanoparticles as a dual-modal probe for multicolor fluorescence and magnetic resonance imaging.

Synthesis of fluorescent ionic liquid-functionalized silicon nanoparticles with tunable amphiphilicity and selective determination of Hg2+

Label-free fluorescent ionic liquid-functionalized silicon nanoparticles with tunable amphiphilicity for highly sensitive and selective detection of Hg²⁺ were synthesized.

Optical techniques for cervical neoplasia detection

This paper provides an overview of the current research in the field of optical techniques for cervical neoplasia detection and covers a wide range of the existing and emerging technologies. Using colposcopy, a visual inspection of the uterine cervix with a colposcope (a binocular microscope with 3- to 15-fold magnification), has proven to be an efficient approach for the detection of invasive cancer. Nevertheless, the development of a reliable and cost-effective technique for the identification of precancerous lesions, confined to the epithelium (cervical intraepithelial neoplasia) still remains a challenging problem. It is known that even at early stages the neoplastic transformations of cervical tissue induce complex changes and modify both structural and biochemical properties of tissues. The different methods, including spectroscopic (diffuse reflectance spectroscopy, induced fluorescence and autofluorescence spectroscopy, Raman spectroscopy) and imaging techniques (confocal microscopy, optical coherence tomography, Mueller matrix imaging polarimetry, photoacoustic imaging), probe different tissue properties that may serve as optical biomarkers for diagnosis. Both the advantages and drawbacks of these techniques for the diagnosis of cervical precancerous lesions are discussed and compared.