Fluorescent Silicon Nanoparticles Research Articles

Fabrication of Yellow-Emitting Chiral Silicon Nanoparticles and Fluorescence/Colorimetric Dual-Mode Recognition of Lysine Enantiomers together with Nanobioimaging.

Long-wavelength emission fluorescent chiral silicon nanoparticles (c-SiNPs) hold significant potential for biological imaging and complex sample analysis due to their superior optical properties. However, the synthesis of these materials remains a considerable challenge. The activity of lysine is intrinsically linked to its configuration, making it crucial to develop a rapid, sensitive, and selective method for differentiating lysine enantiomers in biochemical and biomedical fields. In this study, N-[3-(trimethoxysilyl)propyl]ethylenediamine and chlorogenic acid were innovatively employed as precursors, and the yellow-emitting c-SiNPs with an emission wavelength of 572 nm were synthesized at room temperature for the first time by adjusting experimental parameters. The obtained c-SiNPs exhibited excellent optical properties, stability, and cell compatibility. Furthermore, the c-SiNPs demonstrated outstanding fluorescence and colorimetric recognition capabilities for lysine enantiomers. Consequently, fluorescence/colorimetric dual-mode sensing methods with high selectivity and sensitivity for the recognition of lysine enantiomers were established, and the linear ranges of these methods for d-lysine were 0.050-20 and 0.10-30 mM, with detection limits of 7.5 and 17 μM, respectively. Additionally, the c-SiNPs demonstrated an ability to bioimaging d-lysine within HeLa cells. Using density functional theory to calculate the recognition mechanism and correlating this with fluorescence and ultraviolet-visible (UV-vis) absorption spectra data, it was confirmed that the recognition mechanism was associated with the Gibbs free energy, binding energy, and hydrogen bond number difference between the c-SiNPs and lysine enantiomers. The method developed in this study for preparing c-SiNPs provided a reference for synthesizing fluorescent c-SiNPs with longer emission wavelengths. Moreover, the established method for identifying lysine enantiomers holds significant guiding implications for the use of high-purity lysine.

A Dual Emission Fluorescence Probe Based on Silicon Nanoparticles and Rhodamine B for Ratiometric Detection of Kaempferol.

In this paper, blue fluorescent silicon nanoparticles (SiNPs) with outstanding optical properties and robust stability were synthesized by a simple one-step hydrothermal method. By introducing red emissive rhodamine B (RhB) into SiNPs solution, a dual emission nanoprobe (SiNPs@RhB) was constructed, which showed excellent pH stability, salt resistance and photobleaching resistance. The SiNPs@RhB probe could emit two peaks at 444nm and 583nm under 365nm excitation. It was found that the fluorescence intensity of the two emission peaks decreased in different degrees with the addition of different concentrations of kaempferol (Kae). According to this phenomenon, a novel ratiometric fluorescence method was established for the detection of Kae via utilizing SiNPs@RhB as nanoprobe. The detection range and limit of detection (LOD) were 0.5 ~ 150 µM and 0.24 µM, respectively. The ratiometric fluorescence method exhibited the superiority of rapid detection, excellent stability, wide linear range and high sensitivity. The detection mechanism was studied by ultraviolet visible absorption spectra, fluorescence spectra and fluorescence lifetime. Furthermore, the method was applied to the detection of Kae in real samples (kaempferia powder, sea buckthorn granules and sea buckthorn dry emulsion).

Designing a Hypoxia-Activated Sensing Platform Using an Azo Group-Triggered Reaction with the Formation of Silicon Nanoparticles.

Hypoxia is known as a specific signal of various diseases, such as liver fibrosis. We designed a hypoxia-sensitive fluorometric approach that cleaved the azo bond (N═N) in the presence of hypoxia-controlled agents (sodium dithionite and azoreductase). 4-(2-Pyridylazo) resorcinol (Py-N═N-RC) bears a desirable hypoxia-responsive linker (N═N), and its azo bond breakup can only occur in the presence of sodium dithionite and azoreductase and leads to the release of 2,4-dihydroxyaniline, which can react with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane to generate yellow fluorescent silicon nanoparticles. This approach exhibited high selectivity and sensitivity toward both sodium dithionite and azoreductase over other potential interferences. The mouse liver microsome, which is known to contain azoreductase, was applied and confirmed the feasibility of the designed platform. Py-N═N-RC is expected to be a practical substrate for hypoxia-related biological analyses. Furthermore, silicon nanoparticles were successfully applied for Hela cell imaging owing to their negligible cytotoxicity and superb biocompatibility.

Enantioselective Glutamic Acid Discrimination and Nanobiological Imaging by Chiral Fluorescent Silicon Nanoparticles.

Enantioselective discrimination of chiral molecules is essential in chemistry, biology, and medical science due to the configuration-dependent activities of enantiomers. Therefore, identifying a specific amino acid and distinguishing it from its enantiomer by using nanomaterials with outstanding performance are of great significance. Herein, blue- and green-emitting chiral silicon nanoparticles named bSiNPs and gSiNPs, respectively, with excellent water solubility, salt resistance, pH stability, photobleaching resistance, biocompatibility, and ability to promote soybean germination, were fabricated in a facile one-step method. Especially, chiral gSiNPs presented excellent fluorescence recognition ability for glutamic acid enantiomers within 1 min, and the enantiomeric recognition difference factor was as high as 9.0. The mechanism for enantiomeric fluorescence recognition was systematically explored by combining the fluorescence spectra with density functional theory (DFT) calculation. Presumably, the different Gibbs free energy and hydrogen-bonding interaction of the chiral recognition module with glutamic acid enantiomers mainly contributed to the difference in the fluorescence signals. Most noteworthy was the fact that the chiral gSiNPs can showcase not only the ability to recognize l- and d-glutamic acids in living cells but also the test strips fabricated by soaking gSiNPs can be applied for d-glutamic acid visual detection. As a result, this study provided insights into the design of multifunctional chiral sensing nanoplatforms for enantiomeric detection and other applications.

Silicon Nanoparticle-Based Ratiometric Fluorescence Probes for Highly Sensitive and Visual Detection of VB2.

In this work, blue fluorescent silicon nanoparticles (SiNPs) were prepared by a simple one-step hydrothermal method using (3-aminopropyl) triethoxy silane (APTES) and eriochrome black T as raw materials. The SiNPs showed favorable water solubility, thermal stability, pH stability, salt tolerance, and photobleaching resistance. At an excitation wavelength of 376 nm, the SiNPs emitted bright blue fluorescence at 460 nm. In the presence of vitamin B2 (VB2), the fluorescence intensity (FL intensity) of the SiNPs at 460 nm decreased obviously, and a new peak appeared at 521 nm. Based on this, a novel ratiometric fluorescence method was established for VB2 detection. There was a good linear relationship between the fluorescence intensity ratio (F 521/F 460) and VB2 concentration from 0.5 to 60 μM with a detection limit of 135 nM. This method was successfully applied to detect VB2 content in the samples of vitamin B2 drugs and beverages. Additionally, a simple paper sensor based on the SiNPs was designed to visualize detection of VB2. With the support of color recognition software on a smartphone, the visual quantitative analysis of VB2 was realized, ranging from 40 to 800 μM.

Multimode Sensing Platform Based on Turn-On Fluorescent Silicon Nanoparticles for Monitoring of Intracellular pH and GSH.

Various physiological activities and metabolic reactions of cells need to be carried out under the corresponding pH environment. Intracellular GSH as an acid tripeptide and an important reducing substance also plays an important role in maintaining cellular acid-base balance and redox balance. Therefore, developing a method to monitor pH and GSH and their changes in cells is necessary. Herein, we developed a novel turn-on fluorescent silicon nanoparticles (SiNPs) using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane as the silicon source and dithiothreitol as the reducing agent via a one-pot hydrothermal method. It was worth mentioning that the fluorescence intensity of the SiNPs increased along with the acidity increase, making the SiNPs have excellent pH and GSH sensing capability. Furthermore, the pH and GSH sensing performance of the SiNPs in the cell was verified by confocal imaging and flow cytometry experiment. Based on the above, the prepared SiNPs had the potential to be used as an intracellular pH and GSH multimode fluorescent sensing platform and exhibited the ability to distinguish between normal cells and cancer cells.

Facile synthesis of yellow-green fluorescent silicon nanoparticles and their application in detection of nitrophenol isomers

A clear formation mechanism is essential for the controllable synthesis of nanomaterials with different optical properties, which is also one of the challenges facing the preparation of fluorescent silicon nanomaterials. In this work, a one-step room temperature synthesis method was established to prepare yellow-green fluorescent silicon nanoparticles (SiNPs). The obtained SiNPs exhibited excellent pH stability, salt tolerance, anti-photobleaching ability and biocompatibility. Based on X-ray photoelectron spectroscopy, transmission electron microscopy, ultra high performance liquid chromatography tandem mass spectrometry and other characterization data, the formation mechanism of the SiNPs was proposed, which provided a theoretical basis and important reference for the controllable preparation of SiNPs and other fluorescent nanomaterials. In addition, the obtained SiNPs illustrated excellent sensitivity for nitrophenol isomers, the linear range of o-nitrophenol, m-nitrophenol, p-nitrophenol was 0.05–600 μM, 20–600 μM and 0.01–600 μM under the λex and λem were set as 440 nm and 549 nm, and related limit detection was 16.7 nM, 6.7 μM and 3.3 nM, respectively. The developed SiNP-based sensor achieved satisfactory recoveries in detecting nitrophenol isomers in a river water sample, showing great promise in practical applications.

A turn-on fluorescence assay of tyrosinase activity based on an enzyme-triggered hydroxylation of phenol for conformation of silicon nanoparticles

Evolution of fluorometric sensing methods has brought an enormous opportunity and exhibited novel potentials for enzymatic activities determination. Herein, we have established an accurate and straightforward fluorescent sensing approach for tyrosinase (TYR) activity based on the formation of fluorescent silicon nanoparticles (Si NPs). Influenced by TYR-induced hydroxylation of phenol into catechol, and an easy reaction between catechol and 3(2-aminoethylamino) propyl (dimethoxymethylsilane) (AEAPDMMS) to generate Si NPs, we have designed a label-free fluorescence turn-on probe for TYR activity measurement. After optimization of all reaction parameters, the proposed approach could selectively determine TYR activity in the linearity range of 0.08–9 U mL−1 with the limit of detection (LOD) of 0.03 U mL−1. The practicability of the method in real sample was assessed by measuring TYR activity in human serum sample with successful results. In addition, Si NPs were wonderfully acceptable for Hela and SiHa cells imaging by virtue of their tolerable cytotoxicity and impressive biocompatibility. Therefore, the designed fluorescent biosensor exhibited a potential and widespread implementation in clinical diagnoses assays.

Green synthesis of yellow-green emissive silicon nanoparticles and their application for the sensitive fluorescence detection of bilirubin.

Bilirubin, a tetrapyrrole compound metabolized by heme, is an important biomarker for diagnosis and prognosis of patients with liver diseases. Highly sensitive detection of bilirubin is essential for disease prevention and treatment. In recent years, silicon nanoparticles (SiNPs) have received intense attention due to their excellent optical properties and environmental friendliness. In this paper, water-soluble yellow-green fluorescent SiNPs were synthesized by a mild water bath method using 2-aminophenylboronic acid hydrochloride as the reducing agent and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AEEA) as the silicon source. The preparation process does not require high temperature, high pressure and complex modifications. The SiNPs possessed excellent photostability and good water dispersibility. It was found that the fluorescence of SiNPs at 536 nm could be significantly quenched by bilirubin. By using SiNPs as a fluorescent probe, a novel fluorescence method for sensitive detection of bilirubin was established with a wide linear range of 0.05-75 μM and a limit of detection (LOD) of 16.67 nM. The detection mechanism was mainly due to the internal filtration effect (IFE). More significantly, the established method could successfully determine the contents of bilirubin in biological samples with good recoveries.

Water-borne, durable and multicolor silicon nanoparticles/sodium alginate inks for anticounterfeiting applications

Recently, water-borne fluorescent inks have attracted extensive attention in anti-counterfeiting applications due to their convenient implementation and eco-friendliness. However, due to poor service durability, the latent authorization information from the inks is easily damaged, and even disappears when encountering water. Moreover, most of the existing fluorescent inks are monochromic, toxic, and allergic to skin, thus are unsuitable for their sustainability during real-life applications. Herein, this work presents environment-friendly, durable, and multicolor fluorescent anti-counterfeiting silicon nanoparticles (SiNPs)/sodium alginate (SA) inks. The multicolor SiNPs are synthesized by a one-pot method with defined morphologies and optical properties. Subsequently, SA is employed as the binder to prepare the fluorescent inks with optimized rheological properties. Practicability results show that the SiNPs/SA inks not only exhibit excellent printability, but also impart authentic information with superior covert performance. More notably, spraying solution of calcium dichloride can further improve fluorescent fastnesses of the SiNPs/SA inks by ionic crosslinking.

Water Soluble Silicon Nanoparticles as a Fluorescent Probe for Highly Sensitive Detection of Rutin.

In this work, water-soluble fluorescent silicon nanoparticles (SiNPs) were prepared by one-pot hydrothermal method using 3-(2-aminoethylamino)propyldimethoxymethylsilane (AEAPDMMS) as a silicon source and amidol as a reducing agent. The prepared SiNPs showed bright green fluorescence, excellent stability against photobleaching, salt tolerance, temperature stability, and good water solubility. Due to the internal filtration effect (IFE), rutin could selectively quench the fluorescence of the SiNPs. Based on such phenomena, a highly sensitive fluorescence method was established for rutin detection. The linear range and limit of detection (LOD) were 0.05–400 μM and 15.2 nM, respectively. This method was successfully applied to detect rutin in the samples of rutin tablets, Sophora japonica, fry Sophora japonica, and S. japonica carbon with satisfactory recovery.

“Two-in-one” sulfur and nitrogen co-doped fluorescent silicon nanoparticles: Simultaneous as the fluorescent probe and photocatalyst for in-situ real time visual monitoring and degradation of tetracycline antibiotics

Detection and removal of contaminants are significant for environmental monitoring and remediation. In the present study, “two-in-one” silicon nanoparticles (SiNPs) were designed and prepared to simultaneously act as the fluorescent probe and degradation catalyst to detect and remove tetracycline (TCs) antibiotics. Thiourea and 3-aminopropyltrimethoxysilane were dopant and silicon source to generate fluorescent sulfur and nitrogen co-doped SiNPs (SN-SiNPs). The blue fluorescence of SN-SiNPs was selectively quenched by TCs due to the inner filter effect, whilst accompanied by the newly appeared yellow-green fluorescence resulting from aggregation induced fluorescence emission effect. Based on this phenomenon, SN-SiNPs can be used as fluorescent colorimetric probes for detection of doxycycline, oxytetracycline and tetracycline with limits of detection of 1.8 μg/L, 3.0 μg/L and 4.2 μg/L, respectively; the semi-quantitation can even be visually achieved by naked eyes. Particularly, SN-SiNPs were capable to catalyze the degradation of the three TCs effectively, achieving the removal rates of doxycycline, oxytetracycline and tetracycline of >90 %, >80 % and > 70 % after 240 min exposure to UV light. The catalytic ability of SN-SiNPs was derived from hydroxyl radical (•OH−), superoxide radical (•O2−) and singlet oxygen (1O2) produced by SN-SiNPs under UV irradiation. Moreover, integrating the fluorescent probe and photocatalyst together, the proposed SN-SiNPs simultaneously realized catalyzing the degradation of the three TCs and in-situ visually monitoring of the degradation process in real time. This study innovatively proposed an integrated probe for the detection and catalytic degradation of TCs, providing a new “two-in-one” strategy for rapid and simple detection and removal of drug pollutants.

Water dispersible green fluorescent silicon nanoparticles for high sensitive detection of curcumin and cell imaging

• Green fluorescent SiNPs were prepared by one-step hydrothermal method. • A high sensitive fluorescent method was established for curcumin detection. • The mechanism of the SiNPs to curcumin was the combination of IFE and electrostatic interaction. • The SiNPs were used for imaging with HeLa cells. In this work, water dispersible green fluorescent silicon nanoparticles (SiNPs) were synthesized by one-pot hydrothermal method using 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AEEA) as silicon source and amidol as reducing agent. The SiNPs features outstanding photobleaching resistance, salt resistance, water dispersion, and biocompatibility. The fluorescence of SiNPs could be distinctly quenched by curcumin via internal filtration effect (IFE) and electrostatic interaction. Based on this, a high sensitive fluorescent method for curcumin detection was established with a wide linear range of 0.05–50 µM and a limit of detection (LOD) as low as 15.2 nM. The developed method exhibited the advantages of high sensitivity, rapid response, low cost and simplicity. The method has been successfully applied to determine the content of curcumin in the actual samples of capsule health care products and curry powder. Additionally, owing to the negligible cytotoxicity and outstanding biocompatibility, SiNPs could be used for imaging with HeLa cells. Green fluorescent SiNPs were prepared by a hydrothermal method using 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane as silicon source and amidol as reducing agent. A high sensitive fluorescent method based on the prepared SiNPs was established for curcumin detection via internal filtration effect and electrostatic interaction. The proposed method exhibited the advantages of high sensitivity, rapid response, low cost and simplicity.

Dual Stimuli-Responsive Multifunctional Silicon Nanocarriers for Specifically Targeting Mitochondria in Human Cancer Cells.

Specific targeting, selective stimuli-responsiveness, and controlled release of anticancer agents are requested for high therapeutic efficiency with a minimal adverse effect. Herein, we report the sophisticated synthesis and functionalization of fluorescent mesoporous silicon (FMPSi) nanoparticles decorated with graphene oxide (GO) nanosheets. GO-wrapped FMPSi (FMPSi@GO) was loaded with a cisplatin (Cis) anticancer agent, and Cis-loaded FMPSi@GO (FMPSi-Cis@GO) exhibited the dual stimuli (pH and NIR)-responsiveness of controlled drug release, i.e., the drug release rate was distinctly enhanced at acidic pH 5.5 than at neutral pH 7.0 and further enhanced under NIR irradiation at acidic pH condition. Notably, dequalinium-conjugated FMPSi-Cis@GO (FMPSi-Cis@GO@DQA) demonstrated an excellent specificity for mitochondrial targeting in cancer cells without noticeable toxicity to normal human cells. Our novel silicon nanocarriers demonstrated not only stimuli (pH and NIR)-responsive controlled drug release, but also selective accumulation in the mitochondria of cancer cells and destroying them.

One-pot facile synthesis of bright blue emitting silicon nanoparticles for sensitive detection of luteolin via inner filter effect

Luteolin has gained extensive attention in pharmaceutical and clinical fields owing to their beneficial effects for human health. Accurate detection of luteolin is quite important for drug quality control and clinical medicine research. In this work, novel water dispersible fluorescent silicon nanoparticles (SiNPs) were prepared via one-pot hydrothermal approach by using (3-aminopropyl)trimethoxysilane (APTMS) as silicon source and D-penicillamine as reducing agent. The synthesized SiNPs emitted bright blue fluorescence with a high quantum yield of 44.78% and displayed outstanding optical properties and excellent stability. The fluorescence of the SiNPs could be distinctly quenched by luteolin through inner filter effect (IFE). Based on this, a novel fluorescent method for luteolin detection was developed by using the SiNPs as probe. A linear relationship between the fluorescence quenching efficiency and the concentration of luteolin was obtained from 1 to 100 µM with a limit of detection (LOD) of 0.24 µM. The proposed method was successfully applied to detect luteolin in urine samples.

The In Vivo Toxicity Assessments of Water-Dispersed Fluorescent Silicon Nanoparticles in Caenorhabditis elegans.

Fluorescent silicon nanoparticles (SiNPs), resembling a typical zero-dimensional silicon nanomaterial, have shown great potential in a wide range of biological and biomedical applications. However, information regarding the toxicity of this material in live organisms is still very scarce. In this study, we utilized Caenorhabditis elegans (C. elegans), a simple but biologically and anatomically well-described model, as a platform to systematically investigate the in vivo toxicity of SiNPs in live organisms at the whole-animal, cellular, subcellular, and molecular levels. We calculated the effect of SiNPs on C. elegans body length (N ≥ 75), lifespan (N ≥ 30), reproductive capacity (N ≥ 10), endocytic sorting (N ≥ 20), endoplasmic reticulum (ER) stress (N ≥ 20), mitochondrial stress (N ≥ 20), oxidative stress (N ≥ 20), immune response (N ≥ 20), apoptosis (N ≥ 200), hypoxia response (N ≥ 200), metal detoxification (N ≥ 200), and aging (N ≥ 200). The studies showed that SiNPs had no significant effect on development, lifespan, or reproductive ability (p > 0.05), even when the worms were treated with a high concentration (e.g., 50 mg/mL) of SiNPs at all growth and development stages. Subcellular analysis of the SiNP-treated worms revealed that the intracellular processes of the C. elegans intestine were not disturbed by the presence of SiNPs (p > 0.05). Toxicity analyses at the molecular level also demonstrated that the SiNPs did not induce harmful or defensive cellular events, such as ER stress, mitochondria stress, or oxidative stress (p > 0.05). Together, these findings confirmed that the SiNPs are low in toxicity and biocompatible, supporting the suggestion that the material is an ideal fluorescent nanoprobe for wide-ranging biological and biomedical applications.

One-step hydrothermal synthesis of fluorescent silicon nanoparticles for sensing sulfide ions and cell imaging

We have presented a hydrothermal approach for synthesizing fluorescent silicon nanoparticles (F-SiNPs) with yellow-green emission. The obtained F-SiNPs exhibited excellent stability and good biocompatibility. By virtue of the specific reaction between S2- and 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB), colorimetric assay of S2- was realized with a good linear range of 0–100 μM. The colorimetric detection system could be further combined with F-SiNPs to construct a probe for fluorescence turn-off sensing S2- in aqueous solution due to inner filter effect. In the fluorescent detection system, a good linearity with S2- concentration in the range of 0–50 μM was accomplished. And as low as 0.1 μM S2- was successfully detected. Moreover, the F-SiNPs displayed low cytotoxicity and good biocompatibility, and was further utilized for cell imaging. These results demonstrated the promising applications of F-SiNPs in S2- analysis and bioimaging.

Designing Biosensing Platform for Β-Glucuronidase Determination Based on the Formation of Fluorescent Silicon Nanoparticles

Designing Biosensing Platform for Β-Glucuronidase Determination Based on the Formation of Fluorescent Silicon Nanoparticles

Green-emitting silicon nanoparticles as a fluorescent probe for highly-sensitive crocin detection and pH sensing

Novel green fluorescent silicon nanoparticles were synthesized via a one-pot hydrothermal method and utilized as a fluorescent probe for highly sensitive and accurate detection of crocin and pH sensing.

Green- and Red-Emitting Fluorescent Silicon Nanoparticles: Synthesis, Mechanism, and Acid Phosphatase Sensing.

Until now, the green and facile synthesis of multicolor fluorescent silicon nanoparticles (SiNPs) with favorable biocompatibility for cellular imaging and biosensors is still a challenge. Herein, a facile one-step room temperature method for preparing fluorescent SiNPs displayed different emission wavelengths was reported. Green and red fluorescent SiNPs (G-SiNPs and R-SiNPs) were synthesized by adjusting the concentration of the reducing agent 2,4-diaminophenol hydrochloride when the amount of N-[3-(trimethoxysilyl)-propyl]-ethylenediamine was consistent. Characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, the results revealed that the G-SiNPs and R-SiNPs were assembled by polymerization of different building blocks, and the emission characteristics of these SiNPs were attributed to the difference in their structural composition and particle size. Interestingly, these fluorescent SiNPs exhibited excellent water solubility, salt tolerance, pH stability, photobleaching resistance, and low cytotoxicity, which facilitated multicolor cell imaging, and further led to these SiNPs were highly attractive in a variety of applications, such as multi-channel sensing and biological imaging. Furthermore, the R-SiNPs have shown the potential to detect acid phosphatase, which is a biomarker of prostate cancer.