Biolabeling Applications Research Articles

Crystalline architectures of C84 with tunable morphology and linearly polarized red emission.

Fullerene-based micro/nano-architectures (FMNAs) with remarkable photoluminescence (PL) emissions have attracted considerable interest as potential building blocks for optical and biolabeling applications, by virtue of their low toxicity and environmentally friendly nature. Nevertheless, the PL polarization properties of FMNAs have rarely been explored. Herein, we demonstrate the preparation of highly crystalline architectures of C84, which exhibit polymorphism depending on the preparation conditions but possess similar hexagonal close-packed (hcp) structures. The PL data demonstrate that the as-prepared carambola-like hexagonal microprisms (c-HPs) show enhanced red emission compared to regular hexagonal microprisms (r-HPs). More importantly, the linear polarization of the PL emission is verified and estimated through single-prism spectroscopy, which changes from 0.42 (r-HP) to 0.58 (c-HP), comparable to those of traditional rod-like semiconductors. Thus, we demonstrate a significant correlation between the morphology and emission characteristics of C84-based microprisms, highlighting the possibility of controlling the photophysical properties of FMNAs by finely tailoring their external morphologies. This study expands the range of carbon materials with linearly polarized emissions and offers potential for use in polarization-based micro-scale sensors or detectors.

Remarkable luminescent carbon quantum dots: green synthesis from orange juice using microplasma-liquid method

Green carbon quantum dots (CQDs) were fabricated through microplasma-liquid interactions, involving the treatment of an orange juice solution at atmospheric pressure and room temperature. Morphological analyses of the CQDs revealed a spherical shape with an average size of approximately 2.5 nm. The emission peak at a wavelength of 440 nm was observed for the blue emissive CQDs, with an excitation wavelength of 350 nm. The CQDs exhibited excellent luminescence activity, with emission dependent on the excitation wavelength, shifting towards longer wavelengths. The Raman spectrum of the CQDs displayed two peaks at 1425.3 and 1625.4 cm−1, representing predominantly disorder and graphitic bands. These green-synthesized CQDs possess tunable luminescence and biocompatibility, making them promising candidates for potential applications in biolabelling, antibacterial agents and optoelectronics.

Interrelated Roles of Multiple Key Structure-Directing Agents in Seed-Mediated Growth of Monodisperse and Multibranched Au Nanoparticles.

Detailed mechanistic investigations of the interrelated roles of multiple key structure-directing agents in the growth solution of Au nanoparticles (AuNPs) is required for the optimization of synthetic protocols. Here, we report a robust seed-mediated growth strategy for synthesizing multibranched NPs (MB-AuNPs) with monodispersed size distribution, and investigate the roles of Ag ions and 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES) based on an overgrowth synthesis approach. The intertwining roles of Ag+, surface-capping stabilizers, and reducing agents were elucidated, and used to control the morphology of MB-AuNPs. The overgrowth of MB-AuNPs involves two distinct underlying pathways, namely, directional and anisotropic growth of Au branches on specific facets of Au seeds as well as an aggregation and growth mechanism governed by HEPES. In addition to Ag ions and HEPES, morphology tunability can also be achieved by pre-modification of the Au seeds with molecular probes. Optimized probe-containing MB-AuNPs prove to be excellent surface-enhanced Raman scattering (SERS) substrates and nanozymes. Taken together, the results of this work reveal the mechanistic evolution of nanocrystal growth which should stimulate the development of new synthetic strategies, improve the capabilities of tuning the optical, catalytic, and electronic properties of NPs, and further advance their applications in biolabeling, imaging, biosensing, and therapy.

Structural and lattice dynamics investigation of double luminescent nanosized hybrid Gd2O3

A series of cubic Yb3+/Eu3+ co-doped Gd2O3 using melamine as a complexing ligand have been prepared by low-temperature treatment at 200 °C. Structural and lattice dynamics have been done using XRD and Raman analysis. Photoluminescence analysis of the co-doped Gd2O3 samples is performed at 220, 275, and 980 nm excitations and the plausible mechanism is discussed in detail. The Eu3+ ions asymmetric ratio is calculated as 2.254 in Yb3+ co-doped Gd2O3 lattice. Luminescence lifetimes oscillate between 3.83 and 739 µs. Spectral parameters and J-O intensity parameters are calculated for all co-doped Gd2O3 NPs. Electric-multipole interaction is the energy transfer mechanism responsible for concentration quenching with a critical distance of 11.45 Å in Gd2O3: Yb3+(20 mol%), Eu3+(5 mol%) nanoparticles (NPs) on 980 nm excitation. The sample emits near-white, blue, and orange-red light emissions and can be utilized for bio-labeling applications. Temperature-dependent studies on Gd2O3: Yb3+ (20 mol%), Eu3+ (5 mol%) NPs are performed in the temperature range of 303–478 K. The developed NPs exhibit paramagnetism with a value of 1.580 emu/g owing to Gd3+ intrinsic magnetic moments.

Synthesis of silver nanoclusters in colloidal scaffold for biolabeling and antimicrobial applications

A robust method to prepare silver nanoclusters (AgNCs) inside a methacrylic acid-ethyl acrylate (MAA-EA) nanogel is proposed, where AgNCs were produced within the nanogel scaffold via UV-photoreduction. The impact of UV irradiation time on the formation of AgNCs and their application in biolabeling and antimicrobial properties were examined. The AgNCs formation is described by two stages; (1) Agn (n = 2–8) nanoclusters formation between 0 and 25 min, and (2) larger silver nanoparticles (AgNPs) formed via aggregation inside the nanogel. The antimicrobial performance depended on the size and concentration of silver ions (Ag+). A maximum inhibitory concentration (MIC) of 1.1 ppm was observed for antimicrobial test with yeast, and a MIC of 11 and 22 ppm was recorded for Escherichia. coli and Staphylococcus aureus respectively. Combining with the green illumination property of AgNCs (emitted at 525 nm) with dead yeast, it could be used for biolabeling. By tuning the size through photoirradiation, the nanogel templated AgNCs is a promising candidate for antimicrobial and biolabeling applications.

Synthesis and Photoluminescence Characterization of 3- MPA Capped CdZnTe Quantum Dots

3-MPA capped CdZnTe alloy quantum dots synthesized using Na2TeO3 as the tellurium source under open atmosphere conditions in aqueous medium. The optical and photoluminescence properties of the CdZnTe quantum dots characterized using UV-Visible absorption and Photoluminescence spectrum. An excitonic peak at 527 nm observed in the absorption spectrum. Tauc relation and Urbach relation were employed to find the bandgap energy and urbach energy of the CdZnTe quantum dot. The quantum dot particle size was estimated using the bandgap energy from Tauc plot employing tight binding approximation, which was 4.75 nm. A high intense emission peak at 567 nm obtained in the photoluminescence spectrum. The emission peaks correspond to yellow fluorescence. The CIE chromaticity diagram gives color coordinate at (0.41,0.56) with a color purity of 92%. The high intense yellow fluorescent CdZnTe quantum can placed as potential candidates for fluorescent probes, biolabeling and cell imaging applications.

Evaluating the biocompatibility and biological performance of FePt-decorated nano-epoxy nanoparticles in mesenchymal stem cells.

Nanoparticles have wide potential applications in biolabeling, bioimaging, and cell tracking. Development of dual functional nanoparticles increases the versatility. We combined the fluorescent property of nano-epoxy (N-Epo) and the magnetic characteristic of FePt to fabricate the FePt-decorated N-Epo (N-Epo-FePt). The size in diameter of N-Epo-FePt (177.38 ± 39.25 nm) was bigger than N-Epo (2.28 ± 1.01 nm), both could be absorbed into mesenchymal stem cells (MSCs) via clathrin-mediated endocytosis and have multiple fluorescent properties (blue, green, and red). N-Epo-FePt prevented N-Epo-induced platelet activation, CD68+-macrophage differentiation in blood, and intracellular ROS generation in MSCs. The induction of apoptosis and the inhibitory effects of N-Epo-FePt on cell migration, MMP-9 activity, and secretion of SDF-1α were less than that of N-Epo in MSCs. N-Epo-FePt was more biocompatible without altering biological performance than N-Epo in MSCs. These results suggest that N-Epo-FePt nanoparticle can be used for fluorescence labeling of MSCs and is potential to apply to bioimaging and cell tracking of MSCs in vivo by magnetic resonance imaging or computed tomography.

Activity of CdTe Quantum-Dot-Tagged Superoxide Dismutase and Its Analysis in Capillary Electrophoresis.

Quantum dots (QDs) have a broad range of applications in cell biolabeling, cancer treatment, metastasis imaging, and therapeutic drug monitoring. Despite their wide use, relatively little is known about their influence on other molecules. Interactions between QDs and proteins can influence the properties of both nanoparticles and proteins. The effect of mercaptosuccinic acid-capped CdTe QDs on intercellular copper–zinc superoxide dismutase (SOD1)—one of the main enzymatic antioxidants—was investigated. Incubation of SOD1 with QDs caused an increase in SOD1 activity, unlike in the case of CdCl2, which inhibited SOD1. Moreover, this effect on SOD1 increased with the size and potential of QDs, although the effect became clearly visible in higher concentrations of QDs. The intensity of QD-SOD1 fluorescence, analyzed with the use of capillary electrophoresis with laser-induced fluorescence detection, was dependent on SOD1 concentration. In the case of green QDs, the fluorescence signal decreased with increasing SOD1 concentration. In contrast, the signal strength for Y-QD complexes was not dependent on SOD1 dilutions. The migration time of QDs and their complexes with SOD1 varied depending on the type of QD used. The migration time of G-QD complexes with SOD1 differed slightly. However, in the case of Y-QD complexes with SOD1, the differences in the migration time were not dependent on SOD concentration. This research shows that QDs interact with SOD1 and the influence of QDs on SOD activity is size-dependent. With this knowledge, one might be able to control the activation/inhibition of specific enzymes, such as SOD1.

An In Vitro Study on Inhibiting Pathogenic Activity by Biosynthesized Silver Nanoparticles using Dioscorea Pentaphylla

Development of biologically stimulated experimental processes for the biosynthesis of nanoparticles is an essential branch of nanobiotechnology. Biocompatible silver nanoparticles have acknowledged significant notice in recent years because of their capable applications in bioimaging, biosensors, biolabels, and biomedicine. This study reports a green chemistry approach for the biological synthesis of silver nanoparticles by using the rhizomes extract of Dioscorea Pentaphylla. The properties of synthesis nanoparticles were characterized by UV-Visible spectroscopy, FT-IR, SEM, TEM and EDS. Surface Plasmon Resonance (SPR)
 spectrum for silver nano-particles is obtained at 426 with dark brown color. FT-IR spectroscopy revealed that silver nanoparticles were functionalized with bio- molecules that have primary amine group (NH2), carbonyl phenolic group (-OH) and other stabilizing functional groups. The Morphological studies revealed that the particles are spherical in shape and in the size ranged from 20 ± 1nm. The effects of silver nanoparticles concentration and extract concentration were investigated and DPR-AgNPs showed the better pharma- cological applications.

2D Rare Earth Material (EuOCl) with Ultra-Narrow Photoluminescence at Room Temperature.

High color purity and color rendition of 2D luminescent materials have long been pursued for applications in low-dimensional lighting, display, biolabeling, and laser. However, the reported photoluminescence (PL) linewidth of most 2D luminescent materials is about dozens of meV. Herein, a brand-new luminescent system of 2D rare earth (RE) material EuOCl (1.1nm) with ultra-narrow linewidth (1.2 meV) at room temperature is successfully synthesized via chemical vapor deposition (CVD). The linewidth of EuOCl flakes at room temperature is even narrower than most 2D luminescent materials and heterostructures detected at below 10 K. Impressively, the as-synthesized EuOCl flakes show abnormal temperature-dependent photoluminescent properties, which is absolutely different from the relatively stable 4f-4f transitions in RE owing to shielding from outer shell electrons. J-mixing effect has been successfully applied for this phenomenon. Undoubtedly, luminescent 2D EuOCl flakes will open new territory for the applications of 2D RE materials in the 2D luminescent areas, especially for the applications at room temperature.

Insights into Nucleation and Growth of Colloidal Quaternary Nanocrystals by Multimodal X-ray Analysis.

Copper chalcogenide nanocrystals find applications in photovoltaic inks, bio labels, and thermoelectric materials. We reveal insights in the nucleation and growth during synthesis of anisotropic Cu2ZnSnS4 nanocrystals by simultaneously performing in situ X-ray absorption spectroscopy (XAS) and small-angle X-ray scattering (SAXS). Real-time XAFS reveals that upon thiol injection into the reaction flask, a key copper thiolate intermediate species is formed within fractions of seconds, which decomposes further within a narrow temperature and time window to form copper sulfide nanocrystals. These nanocrystals convert into Cu2ZnSnS4 nanorods by sequentially incorporating Sn and Zn. Real-time SAXS and ex situ TEM of aliquots corroborate these findings. Our work demonstrates how combined in situ X-ray absorption and small-angle X-ray scattering enables the understanding of mechanistic pathways in colloidal nanocrystal formation.

NIR Luminescence Enhancement of YVO4:Nd Phosphor for Biological Application.

This work reports two systematic studies related to yttrium vanadate (YVO4) phosphors. The first evaluates how the annealing temperature and V5+/Y3+ molar ratio determine the emergence of a single YVO4 tetragonal phase, whereas the second concerns the optimal Nd3+ concentration to improve the infrared emission properties for bio-labelling applications. The YVO4:Nd phosphors were synthesized by adapting the non-hydrolytic sol-gel route. For the first study, samples containing different V5+/Y3+ molar ratios (1.02, 1.48, 1.71, or 3.13) were obtained. For the second study, YVO4:Nd phosphors containing different Nd3+ concentrations (1.0, 3.0, 5.0, or 10.0% in mol) were prepared. X-ray diffractometry and RAMAN spectroscopy results revealed that, regardless of the heat-treatment temperature, the V5+/Y3+ molar ratio of 1.48 was the best composition to avoid undesired phases like Y2O3 and V2O5. Photoluminescence results indicated that the sample containing 3.0% in mol of Nd3+ and annealed at 1000°C presented the best infrared emission properties. This sample displayed an intense broad band in the ultraviolet region, which was ascribed to the VO43- charge transfer band, as well as several bands in the visible and infrared regions, which were attributed to the Nd3+ intraconfigurational f-f transitions. Regardless of the excitation wavelength (ultraviolet, visible, or near-infrared), the mean radiative lifetime was about 12.00 µs. The prepared phosphors presented absorption and emission bands in the biological window (BW) regions, which are located between 750 and 900nm and between 1000 and 1300nm, so they are candidates for applications in medical imaging and diagnoses.

Synthesis of Multi-Color Fluorescent Carbon Dots From Mint Leaves: A Robust Bioimaging Agent with Potential Antioxidant Activity.

Carbon dots (C-dots), a promising luminescent nanomaterial with exceptional physico-chemical properties gaining enormous attention in recent years. Carbon dots having enhanced biocompatibility and multiple routes of synthesis offers a promising substitute to luminescent quantum dots (QD). Further, wavelength-controlled emission features of C-dots proved as a good candidate in the biolabeling applications. Herein, we are reporting a facile and one-step hydrothermal synthesis of biocompatible multi-color, Polyethyleneimine (PEI) surface passivated C-dots (CDP) from mint leaves as a green source. The morphological and optical properties of C-dots have been extensively studied by Zeta-sizer, Transmission electron microscopy (TEM), X-ray diffraction (XRD) pattern, Ultra violet (UV)-visible spectroscopy and fluorescence spectroscopic analysis. Furthermore, Fourier transform infrared (FT-IR) and X-Ray Photoelectron Spectroscopic (XPS) analysis have been performed for the understanding of surface states and chemical composition of C-dots. A comparative analysis in the biolabeling potentials of non-passivated C-dots (CD) and CDP was conducted in the breast cancer (MCF-7) cells and the concentration dependent cytotoxicity was estimated. Further, an enhanced antioxidant property was showed by CDP as compared to CD. In the present study, a practical implication of C-dots synthesized from a herbal source (mint) to serve as a novel agent for various biolabeling applications and antioxidant activity have been experimentally resolved. As synthesized CD and CDP can be, serve as better alternatives for imaging probe with improved biocompatibility.

Effect of ytterbium amount on LaNbO4:Tm3+,Yb3+ nanoparticles for bio-labelling applications

PurposeThis work investigates how Yb3+ concentration affects the luminescent properties of LaNbO4 nanoparticles for medical imaging applications. Due to the highly transparent optical window for organic tissues in the near infrared region (650–1000 nm), upconversion fluorescence allows near infrared wavelengths to penetrate deeply into tissues, which is useful in biomedical areas such as biodetection, activated phototherapy, and screening. Materials/methodUpconversion nanoparticles based on LaNbO4 doped with Tm3+ and Yb3+ were prepared by the one-step industrial process called Spray Pyrolysis. Samples with different Tm3+:Yb3+ molar ratios (1:4, 1:8 and 1:16) were obtained. ResultsThe X-ray powder diffractograms of all the samples displayed the typical peaks of a crystalline material (tetragonal phase). Emission bands emerged in the blue, red, and near infrared regions, and they corresponded to the Tm3+1G4 → 3H6 (475 nm), 1G4 → 3F4 (650 nm), 3F2,3 → 3H6 (690 nm), and 3H4 → 3H6 (803 nm) transitions, which indicated a two-photon absorption process. As for bio-labelling application, the results indicated that Yb3+ concentration was directly related to signal intensity. ConclusionsThe intensity of positive conversion emissions depends directly on Yb3+ concentration. The bio-labelling tests pointed to the potential application of these materials. The sample containing the highest amount of Yb3+ provided better results and was easier to detect than the standard sample.

Effect of temperature and etching under light irradiation on the band edge emission of β-mercaptoethanol-capped CdS colloidal nanocrystals

In this work, cadmium sulfide nanocrystals capped with β-mercaptoethanol: CdS–βME (NCs) formed at wurtzite structure were prepared by colloidal chemical method for structural and optical properties' investigation. The temperature dependence of the photoluminescence (PL) intensity and its quantum yield (QY), the PL pic position and FWHM and the PL lifetime were systematically studied over a broad temperature range of 10–300 K. PL enhancement, photoetching and photostability of CdS–βME NCs were investigated under light irradiation. XRD and TEM patterns showed that CdS–βME NCs have an hexagonal phase with wurtzite structure. A very narrow excitonic blue emission peak with relatively high intensity was detected, which is similar to the better results obtained via organic synthesis. The FWHM ($$\sim$$ 20 nm) is controlled by an inhomogeneous broadening due to the particle size/morphology distributions of the NCs. Dynamic studies reveal shorter lifetimes indicating weak contribution of the surface-related emission with the removal of surface defects. The photoetching process of CdS–βME NCs resulted in a high QY of up to 3.8% with an obvious blueshift in band emission. On the basis of these studies, it is established that the surface of CdS–βME is rich with Cd2+ ions, leading to the formation of a CdO layer as shell, which provides a better passivation by removing surface hole traps and confines the charge carriers with illumination by Hg lamp radiation. In conclusion, owing to their excellent dispersibility in water and high luminescence, the CdS–βME NCs that have been developed here can be a promising candidate for biolabelling and imaging applications.

Fluorescent Carbon-Dots Thin Film for Fungal Detection and Bio-labeling Applications.

The fluorescence properties of CDs, such as high quantum yield, tunability of emission color, and so on, make a strong potential material in various fields. These applications are mainly derived from in situ formation of surface functional groups, high chemical stability, biocompatibility, and easy interaction with substrates, etc. Mostly, the research applications of CDs concentrate on the labeling of biological species, drug delivery, and sensing in consequent biomedical applications. However, the detection of the fungal species/spores present in the environment by using CDs is rarely reported. Herein, we demonstrate CDs-based thin film as a sensor for detection of fungal spores from the environment. The procedure of detection is based on fluorescence, observed in the film of carbon dots deposited on quartz plates by using the Blodgett technique. It is observed that the CDs film shows quenching in the fluorescence intensity by the substrate, namely, fungal spores' (Aspergillus niger, Penicillium chrysogenum, Alternaria alternata). The effective features of the present detector system are easy fabrication, low cost, high stability, and a green and economical procedure of synthesis. The process of detecting fungal spores even at low concentration from the atmosphere is relatively fast when compared to presently used methods. Finally, real-world feasibility of the sensor film is tested by its successful application for the determination of the presence fungal spores in the environment. Furthermore, CDs have been also successfully applied for the bio-labeling of Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacterial systems.

One‐Pot Synthesis of Highly Fluorescent Poly(methacrylic acid)‐Capped Silver Nanoclusters for the Specific Detection of Iron(II)

AbstractThis work presented an easy synthesis method for water‐soluble, green and fluorescent silver nanoclusters with poly (methacrylic acid) (AgNCs@PMAA) and preliminarily explored their ability to detect Fe2+ by measuring their fluorescence quenching. The acquired AgNCs@PMAA showed steady, selective, and highly sensitive detection of Fe2+. The Fe2+ detection limit for AgNCs@PMAA was 3 μM, and a linear relationship was observed at 5–150 μΜ ion concentration. AgNCs@PMAA had no biological toxicity and could be used for in vivo imaging and detection of iron ions. This fluorescence detection method based on novel nanomaterials exhibits future application in biolabeling, biosensing, and other purposes.

Two-photon excited photoluminescence of single perovskite nanocrystals.

Lead-halide perovskite nanocrystals (NCs) have emerged as a novel type of semiconductor nanostructure, attracting great research interests in both fundamental science and practical applications. Here, we compare the optical properties of single CsPbI3 NCs under both one-photon and two-photon excitations, mainly including the photoluminescence (PL) blinking and PL decay dynamics. By means of the PL saturation effect caused by multi-exciton Auger recombination, we have also estimated a two-photon absorption cross section of ∼6.8 × 106 GM for single CsPbI3 NCs. The ability to realize efficient two-photon excitation of single perovskite NCs with strongly suppressed background fluorescence will help not only to promote their bio-imaging and biolabeling applications but also to reveal and manipulate their delicate electronic structures for potential usage in quantum information processing.

Chemically Synthesized Carbon Nanorods with Dual Polarized Emission.

We realized the synthesis of carbon nanorods-monodisperse colloidal particles with a length of 50 nm and a width of 20 nm-which can be considered an addition to the family of light-emitting carbon-based nanostructures. Their anisotropic shape is determined by the use of the surfactant aminopropylisobutyl polyhedral oligomeric silsesquioxane, and their optical properties originate from domains of polycyclic aromatic hydrocarbons incorporated within an inorganic framework. The nanorods show dual polarized emission with a quantum yield of 15-20% and emission anisotropy of ∼0.3, which changes from blue (460 nm) to yellow (565 nm) depending on the excitation wavelength. These carbon nanorods expand the range of light-emitting carbon nanomaterials available for optoelectronic and biolabeling applications.

Synthesis of Colloidal Blue-Emitting InP/ZnS Core/Shell Quantum Dots with the Assistance of Copper Cations.

Colloidal InP quantum dots (QDs) have been considered as one of the most promising candidates for display and biolabeling applications because they are intrinsically toxicity-free and exhibit high photoluminescence. On account of the uncontrollable nucleation and growth during the synthesis of InP, obtaining high-quality blue-emitting InP QDs with uniform size distribution remains a challenge. Herein, we employ a novel synthetic approach for producing blue-emitting InP/ZnS core/shell QDs with the assistance of copper cations. The studies reveal that the copper ions could combine with phosphorus precursor to form hexagonal Cu3-xP nanocrystals, which competed with the nucleation process of InP QDs, resulting in the smaller sized InP QDs with blue photoluminescence emission. After the passivation of InP QDs with the ZnS shell, the synthesized InP/ZnS core/shell QDs present bright blue emission (∼425 nm) with a photoluminescence quantum yield of ∼25%, which is the shortest wavelength emission for InP QDs to date. This research provides a new way to synthesize ultrasmall semiconductor nanocrystals.