Fluorescent nanodiamonds: past, present, and future

Multi-color fluorescent nanodiamonds (FNDs) containing a variety of color centers are promising fluorescent markers for biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity, exceptional chemical stability, and better photostability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this article review, we will discuss the current trends in FND’s development, including comparison to the early development of quantum dots. We will also highlight some of the latest advances in fabrication, as well as demonstrations of their use in bioimaging and biosensing

Lanthanide ions doped in vanadium oxide for sensitive optical glucose detection

Blood glucose monitoring is essential to avoid the unwanted consequences of glucose level fluctuations. Optical monitors are of special interest because they can be non-invasive. Among optical glucose sensors, fluorescent upconversion nanoparticles (UCNPs) have the advantage of good photostability, low toxicity, and exceptional autofluorescence suppression. However, to sense glucose, UCNPs normally need surface functionalization, and this can be easily affected by other factors in biological systems, and may also affect their ability for real-time sensing of both increasing and decreasing glucose levels. Here, we report YVO4 : Yb3+, Er3+@Nd3+core/shell UCNPs with Nd and Yb shell and GdVO4 : Yb3+, Er3+@Nd3+ core/shell UCNPs with Nd and Yb shell that show sensitive, reversible, and selective optical glucose detection without the need for any surface functionalization or modifications

High resolution fluorescence bio-imaging upconversion nanoparticles in insects

Imaging fluorescent markers with brightness, photostability, and continuous emission with auto fluorescence background suppression in biological samples has always been challenging due to limitations of available and economical techniques. Here we report a new approach, to achieve high contrast imaging inside small and difficult biological systems with special geometry such as fire ants, an important agricultural pest, using a homemade cost-effective optical system. Unlike the commonly used rare-earth doped fluoride nanoparticles, we utilized nanoparticles with a high upconversion efficiency in water. Specifically Y_2O_3:Er^(+3),Yb^(+3) nanoparticles (40-50 nm diameter) were fed to fire ants as food and then a simple illuminating experiment was conducted at 980 nm wavelength at relatively low pump intensity 8 kW.cm^(−2). The locations were further confirmed by X-ray tomography, where most particles aggregated inside the ant’s mouth. High resolution, fast, and economical optical imaging system opens the door for studying more complex biological system

Engineering Fluorescent Nanodiamonds and Upconversion Nanoparticles for Bioimaging and Optical Temperature Sensing

An ideal fluorescent marker for high contrast imaging and optical temperature sensing in biological applications should be biocompatible, ultrasmall, photostable, and can be excited and detected within the biological transparency window (650-1350nm). To meet these criteria, fluorescent nanodiamonds (FNDs) and upconversion nanoparticles (UCNPs) doped with lanthanide ions Ln+³ (Ln=Er,Tm,Ho,etc.) are of interest. First, multi-color fluorescent nanodiamonds (FNDs) containing variety of color centers are promising fluorescent markers for most of biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity and better photostability. FNDs can be as small as fluorescent proteins, for example, green fluorescent protein (GFP) with a few nanometers (nm) in size and have exceptional chemical stability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this dissertation, I will discuss a new technique of grown small and stable fluorescent nanodiamonds. I will also discuss some applications of FNDs in bioimaging and biosensing. Second, Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, Y V O₄ : Er+³, Yb+³ nanoparticles were shown to exhibit strong up-conversion luminescence (UCL) with a relatively low 10 kW.cm⁻² excitation intensity even in water, which makes them excellent bio-imaging and biosensors candidates. In this dissertation, I will discuss the UCNPs in terms of synthesis, applications in bioimaging and biosensing

Engineering Fluorescent Nanodiamonds and Upconversion Nanoparticles for Bioimaging and Optical Temperature Sensing

An ideal fluorescent marker for high contrast imaging and optical temperature sensing in biological applications should be biocompatible, ultrasmall, photostable, and can be excited and detected within the biological transparency window (650-1350nm). To meet these criteria, fluorescent nanodiamonds (FNDs) and upconversion nanoparticles (UCNPs) doped with lanthanide ions Ln+³ (Ln=Er,Tm,Ho,etc.) are of interest. First, multi-color fluorescent nanodiamonds (FNDs) containing variety of color centers are promising fluorescent markers for most of biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity and better photostability. FNDs can be as small as fluorescent proteins, for example, green fluorescent protein (GFP) with a few nanometers (nm) in size and have exceptional chemical stability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this dissertation, I will discuss a new technique of grown small and stable fluorescent nanodiamonds. I will also discuss some applications of FNDs in bioimaging and biosensing. Second, Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, Y V O₄ : Er+³, Yb+³ nanoparticles were shown to exhibit strong up-conversion luminescence (UCL) with a relatively low 10 kW.cm⁻² excitation intensity even in water, which makes them excellent bio-imaging and biosensors candidates. In this dissertation, I will discuss the UCNPs in terms of synthesis, applications in bioimaging and biosensing

Efficient Lithium-Based Upconversion Nanoparticles for Single-Particle Imaging and Temperature Sensing

Upconversion Nanoparticles (UCNPs) have attracted exceptional attention due to their great potential in high-contrast, free-background biofluorescence deep tissue imaging and quantum sensing. Most of these interesting studies have been performed using an ensemble of UCNPs as fluorescent probes in bioapplications. Here, we report a synthesis of small and efficient YLiF4:Yb,Er UCNPs for single-particle imaging as well as sensitive optical temperature sensing. The reported particles demonstrated a bright and photostable upconversion emission at a single particle level under a low laser intensity excitation of 20 W/cm2. Furthermore, the synthesized UCNPs were tested and compared to the commonly used two-photon excitation QDs and organic dyes and showed a nine times better performance at a single particle level under the same experimental conditions. In addition, the synthesized UCNPs demonstrated sensitive optical temperature sensing at a single particle level within the biological temperature range. The good optical properties of single YLiF4:Yb,Er UCNPs open an avenue for small and efficient fluorescent markers in imaging and sensing applications

Upconversion nanoparticles based on rare-earth elements

Using the hydrothermal method, we synthesized water soluble YVO4: Yb, Er nanoparticles with a size less than 10 nm. Nanoparticles exhibit intense luminescence in the green region due to Er3+ ions when excited by laser radiation at a wavelength of 980 nm as a result of the up-conversion process. Bright and stable luminescence also persists in an aqueous solution of nanoparticles. Based on experimental data, it can be argued that the objects obtained are promising in biological applications, as well as up-conversion phosphors

Upconversion nanoparticles based on rare-earth elements

Using the hydrothermal method, we synthesized water soluble YVO4: Yb, Er nanoparticles with a size less than 10 nm. Nanoparticles exhibit intense luminescence in the green region due to Er3+ ions when excited by laser radiation at a wavelength of 980 nm as a result of the up-conversion process. Bright and stable luminescence also persists in an aqueous solution of nanoparticles. Based on experimental data, it can be argued that the objects obtained are promising in biological applications, as well as up-conversion phosphors

Electrodeposition of Lithium-Based Upconversion Nanoparticle Thin Films for Efficient Perovskite Solar Cells

In this work, high-quality lithium-based, LiYF4=Yb3+,Er3+ upconversion (UC) thin film was electrodeposited on fluorene-doped tin oxide (FTO) glass for solar cell applications. A complete perovskite solar cell (PSC) was fabricated on top of the FTO glass coated with UC thin film and named (UC-PSC device). The fabricated UC-PSC device demonstrated a higher power conversion efficiency (PCE) of 19.1%, an additional photocurrent, and a better fill factor (FF) of 76% in comparison to the pristine PSC device (PCE = ~16.57%; FF = 71%). Furthermore, the photovoltaic performance of the UC-PSC device was then tested under concentrated sunlight with a power conversion efficiency (PCE) of 24% without cooling system complexity. The reported results open the door toward efficient PSCs for renewable and green energy applications