Nanoparticulated Bimodal Contrast Agent for Ultra-High-Field Magnetic Resonance Imaging and Spectral X-ray Computed Tomography

Bimodal medical imaging based on magnetic resonance imaging (MRI) and computed tomography (CT) is a well-known strategy to increase the diagnostic accuracy. The most recent advances in MRI and CT instrumentation are related to the use of ultra-high magnetic fields (UHF-MRI) and different working voltages (spectral CT), respectively. Such advances require the parallel development of bimodal contrast agents (CAs) that are efficient under new instrumental conditions. In this work, we have synthesized, through a precipitation reaction from a glycerol solution of the precursors, uniform barium dysprosium fluoride nanospheres with a cubic fluorite structure, whose size was found to depend on the Ba/(Ba + Dy) ratio of the starting solution. Moreover, irrespective of the starting Ba/(Ba + Dy) ratio, the experimental Ba/(Ba + Dy) values were always lower than those used in the starting solutions. This result was assigned to lower precipitation kinetics of barium fluoride compared to dysprosium fluoride, as inferred from the detailed analysis of the effect of reaction time on the chemical composition of the precipitates. A sample composed of 34 nm nanospheres with a Ba0.51Dy0.49F2.49 stoichiometry showed a transversal relaxivity (r2) value of 147.11 mM-1·s-1 at 9.4 T and gave a high negative contrast in the phantom image. Likewise, it produced high X-ray attenuation in a large range of working voltages (from 80 to 140 kVp), which can be attributed to the presence of different K-edge values and high Z elements (Ba and Dy) in the nanospheres. Finally, these nanospheres showed negligible cytotoxicity for different biocompatibility tests. Taken together, these results show that the reported nanoparticles are excellent candidates for UHF-MRI/spectral CT bimodal imaging CAs.

Tuning the Red-to-Green-Upconversion Luminescence Intensity Ratio of Na3ScF6: 20% Yb3+, 2% Er3+ Particles by Changes in Size

Na₃ScF₆: 20% Yb³⁺, 2% Er³⁺ samples were synthesized with different reaction times and reaction temperatures using the solvothermal method. We carried out a series of tests on Na3ScF6 crystals. The XRD patterns showed that the monoclinic phases of the Na₃ScF₆ samples could be synthesized under different reaction conditions, and doping with Yb³⁺ ions and Er³⁺ ions did not change the crystal structures. The SEM images showed that the sizes of the samples gradually increased with reaction time and reaction temperature. The fluorescence spectra showed that the emission peaks of the prepared samples under 980 nm near-infrared (NIR) excitation were centered at 520 nm/543 nm and 654 nm, corresponding to the ²H_11/2/⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions, respectively. With the increasing size of the samples, the emission intensities at 654 nm increased and the luminescence colors changed from green to red; at the same time, the red-to-green luminescence intensity ratios (IR/IG ratios) increased from 0.435 to 15.106-by as much as ~34.7 times. Therefore, this paper provides a scheme for tuning the IR/IG ratios of Na₃ScF₆: 20% Yb³⁺, 2% Er³⁺ samples by changing their sizes, making it possible to enhance the intensity of red upconversion, which has great potential for the study of color displays and lighting.

Engineered upconversion nanocarriers for synergistic breast cancer imaging and therapy: Current state of art

Breast cancer is the most common type of cancer in women and is the second leading cause of cancer-related deaths worldwide. Early diagnosis and effective therapeutic interventions are critical determinants that can improve survival and quality of life in breast cancer patients. Nanotheranostics are emerging interventions that offer the dual benefit of in vivo diagnosis and therapeutics through a single nano-sized carrier. Rare earth metal-doped upconversion nanoparticles (UCNPs) with their ability to convert near-infrared light to visible light or UV light in vivo settings have gained special attraction due to their unique luminescence and tumor-targeting properties. In this review, we have discussed applications of UCNPs in drug and gene delivery, photothermal therapy (PTT), photodynamic therapy (PDT) and tumor targeting in breast cancer. Further, present challenges and future opportunities for UCNPs in breast cancer treatment have also been mentioned.

Fluorescent Nanoparticles for Super-Resolution Imaging

Super-resolution imaging techniques that overcome the diffraction limit of light have gained wide popularity for visualizing cellular structures with nanometric resolution. Following the pace of hardware developments, the availability of new fluorescent probes with superior properties is becoming ever more important. In this context, fluorescent nanoparticles (NPs) have attracted increasing attention as bright and photostable probes that address many shortcomings of traditional fluorescent probes. The use of NPs for super-resolution imaging is a recent development and this provides the focus for the current review. We give an overview of different super-resolution methods and discuss their demands on the properties of fluorescent NPs. We then review in detail the features, strengths, and weaknesses of each NP class to support these applications and provide examples from their utilization in various biological systems. Moreover, we provide an outlook on the future of the field and opportunities in material science for the development of probes for multiplexed subcellular imaging with nanometric resolution.

Multi-variable compensated quantum yield measurements of upconverting nanoparticles with high dynamic range: a systematic approach

Non-linear materials such as upconverting nanoparticles (UCNPs) are emerging technology with fast-growing applications in various fields. The power density dependence of the emission quantum yield (QY) of these non-linear materials makes them challenging to characterize using currently available commercial QY systems. We propose a multimodal system to measure QY over a wide dynamic range (1:104), which takes into account and compensates for various distorting parameters (scattering, beam profile, inner filter effect and bandwidth of emission lines). For this, a beam shaping approach enabling speckle free beam profiles of two different sizes (530 µm or 106 µm) was employed. This provides low noise high-resolution QY curves. In particular, at low power densities, a signal-to-noise ratio of >50 was found. A Tm-based core-shell UCNP with excitation at 976 nm and emission at 804 nm was investigated with the system.

Recent advances of lanthanide-doped upconversion nanoparticles for biological applications

Near infrared (NIR) excited lanthanide-doped upconversion nanoparticles (UCNPs) are emerging as a new type of fluorescent tag for biological applications, which can emit multi-photon ultraviolet, visible or NIR luminescence for imaging or activation of photosensitive molecules. Here, we present a comprehensive review on recent advances of UCNPs for a manifold of biological applications, including upconversion mechanisms, building bright multicolor upconversion nanocrystals, single nanoparticle and super resolution imaging, in vivo optical and multimodal imaging, photodynamic therapy, light-controlled drug release, biosensing, and toxicities. Our perspectives on the future development of UCNPs are also described.

Fe3+-sensing by 3,3',5,5'-tetramethylbenzidine-functionalized upconversion nanoparticles

Detection of Fe³⁺ ion is essential for human health because it is an important element of hemoglobin, which carries oxygen to cells in the body. Here, a 3,3',5,5'-tetramethylbenzidine (TMB) functionalized NaYF₄: Yb³⁺, Er³⁺@NaYF₄ composite upconversion probe was developed, and demonstrated Fe³⁺ sensing ability with high sensitivity and selectivity. The red emission of upconversion nanoparticles (UCNPs) has a higher penetration depth in tissue than green light and works within the biological window. The obtained hydrophobic NaYF₄: Yb³⁺, Er³⁺@NaYF₄ nanoparticles were treated with HCl to achieve hydrophilic ligand-free nanoparticles with non-saturated metal ions on their surface. Then, a Fe³⁺ responsive TMB-UNCPs composite luminescence probe was formed through linking TMB onto the ligand-free UCNPs by a coordination bond between the NH₂ groups in TMB and the metal ions on the UCNPs. Due to the efficient fluorescence resonance energy transfer from UCNPs to Fe³⁺-TMB, the obtained probe shows high sensitivity for detecting Fe³⁺ in the range of 0-100 μM with a detection limit of 0.217 μM. And the color change of the detection system can also be easily recognized by the naked eye. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) experiments and the bioimaging experiments show promising prospects in tissue imaging.

Lanthanide Doped Near Infrared Active Upconversion Nanophosphors: Fundamental Concepts, Synthesis Strategies, and Technological Applications

Near infrared (NIR) light utilization in a range of current technologies has gained huge significance due to its abundance in nature and nondestructive properties. NIR active lanthanide (Ln) doped upconversion nanomaterials synthesized in controlled shape, size, and surface functionality can be combined with various pertinent materials for extensive applications in diverse fields. Upconversion nanophosphors (UCNP) possess unique abilities, such as deep tissue penetration, enhanced photostability, low toxicity, sharp emission peaks, long anti-Stokes shift, etc., which have bestowed them with prodigious advantages over other conventional luminescent materials. As new generation fluorophores, UCNP have found a wide range of applications in various fields. In this Review, a comprehensive overview of lanthanide doped NIR active UCNP is provided by discussing the fundamental concepts including the different mechanisms proposed for explaining the upconversion processes, followed by the different strategies employed for the synthesis of these materials, and finally the technological applications of UCNP, mainly in the fields of bioimaging, drug delivery, sensing, and photocatalysis by highlighting the recent works in these areas. In addition, a brief note on the applications of UCNP in other fields is also provided along with the summary and future perspectives of these materials.

Luminescence property tuning of Yb3+-Er3+ doped oxysulfide using multiple-band co-excitation

Lanthanide ions have abundant excited-state channels which result in a radiation relaxation process generally accompanied by a non-radiation relaxation process. However, non-radiation relaxation processes will consume the activation energy and reduce the luminescence efficiency of the phosphor. Two lasers with an excitation energy which matched the ground state absorption and excited state absorption of ions were used to excite the phosphors to avoid the non-radiation relaxation process. This approach can achieve the purpose of populating specific states of the lanthanide ions, and furthermore effectively tunes the luminescence intensity and color output of the sample. Results show that the red emission intensity of the sample is significantly improved and this is caused by populating the ⁴F_9/2 level under simultaneous 1510 nm and 980 nm excitation. Then when the 1510 nm and 808 nm co-operate to excite the sample, the green emission obtained increased sharply because the ²H_11/2/⁴S_3/2 states were efficiently populated. As a proof-of-concept experiment, this new approach has potential in the applications of solar cells.

The emission intensity of the sample excited by dual-wavelength (980 and 1510 nm) is 3.2 times than the sum of UCL emission under the two single wavelength excitation.

Core-shell structured NaMnF3: Yb, Er nanoparticles for bioimaging applications

A modified thermal decomposition method to synthesize single or core/shell structured lanthanide-doped NaMnF₃ nanoparticles is proposed.

Tuning upconversion through a sensitizer/activator-isolated NaYF₄ core/shell structure

The ability to tune the emission color of upconversion nanoparticles (UCNPs) will greatly enhance the scope of their applications, ranging from infrared solar cells to volumetric multiplexed bioimaging. Conventional methods to tune upconversion are to vary the type and/or the concentration of doped rare-earth ions in these nanoparticle formulations. Here, we introduce a different approach to vary the emission colors of the frequently used sensitizer/activator pairs of Yb(3+)/RE(3+) (RE = Ho, Er, Tm) via utilization of a sensitizer/activator-isolated NaYF4 core-shell structure. We show that the typical green, yellow, and blue luminescent colors from Yb(3+)/Ho(3+)-, Yb(3+)/Er(3+)-, and Yb(3+)/Tm(3+)-co-doped NaYF4 UCNPs can be converted into the quasi-white, green, and pink blue, when corresponding core-shell structures of NaYF4:Yb(3+) @NaYF4:Ho(3+), NaYF4:Yb(3+) @NaYF4:Er(3+) and NaYF4:Yb(3+) @NaYF4:Tm(3+) are built. Time-resolved spectra indicate that decay lifetimes of the emission bands from the sensitizer/activator-isolated core-shell structure significantly vary from that of the sensitizer/activator-codoped NaYF4 UCNPs, verifying the strain-induced modulation of emission channels in the core-shell structure. These sensitizer-activator-isolated core-shell UCNPs have implications for a range of biophotonic or photonic applications.

Probing the nature of upconversion nanocrystals: instrumentation matters

Understanding upconversion nanocrystals: this review intends to summarize instrumental matters related to the characterization of upconversion nanocrystals from surface structures to intrinsic properties to ultimate challenges in nanocrystal analysis at single-particle levels.

Lanthanide-doped upconversion nano-bioprobes: electronic structures, optical properties, and biodetection

The latest advances in lanthanide-doped upconversion nanoparticles were comprehensively reviewed, which covers from their fundamental photophysics to biodetection.

Energy transfer in lanthanide upconversion studies for extended optical applications

In this review, the various energy transfer pathways involved in lanthanide-related upconversion emissions are comprehensively discussed.

Multiplexing determination of lung cancer biomarkers using electrochemical and surface-enhanced Raman spectroscopic techniques

A reliable immunosensor for simultaneous detection of carcinoembryonic antigen and cytokeratin-19 by complementary advantages of the electrochemical and SERS technologies.

Polypeptide-functionalized NaYF4:Yb(3+),Er(3+) nanoparticles: red-emission biomarkers for high quality bioimaging using a 915 nm laser

We prepared poly-L-aspartic acid (PASP) functionalized NaYF4:Yb(3+),Er(3+) upconversion nanoparticles (UCNP-PASP). These nanoparticles can give red upconversion emission under excitation at 915 nm, whose wavelength of emission and excitation is located in the optical window of biological tissue. Dynamic laser scatting and zeta potentials of UCNP-PASP were used to study their stabilities in different aqueous solution. To understand the mechanism of the red emission of UCNP-PASP, photoluminescence spectra of samples were recorded before and after modification with PASP, poly acrylic acid (PAA), and poly(ether imide) (PEI) ligands under excitation at 915 and 980 nm, respectively. The cytotoxicity of the UCNP-PASP was also examined on a A549 cell and KB cell by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. Moreover, the PASP-functionalized UCNP was employed as a potential biomarker for in vitro and in vivo experiments of upconversion luminescence imaging.

Synergetically enhanced near-infrared photoresponse of reduced graphene oxide by upconversion and gold plasmon

A new route to improve responsivity of reduced graphene oxide (rGO)-based near-infrared photodetectors is reported by coupling upconversion and gold plasmon. Near-infrared light is converted by upconversion nanoparticle into shorter wavelengths that can readily be absorbed by rGO. Further coupling of plasmonic layer increased upconversion emissions and rGO absorption, resulting in an overall enhancement of photo-responsivity by 10 times.

Multicolor tuning of lanthanide-doped nanoparticles by single wavelength excitation

Lanthanide-doped nanoparticles exhibit unique luminescent properties, including large Stokes shift, sharp emission bandwidth, high resistance to optical blinking, and photobleaching, as well as the unique ability to convert long-wavelength stimulation into short-wavelength emission. These attributes are particularly needed for developing luminescent labels as alternatives to organic fluorophores and quantum dots. In recent years, the well-recognized advantages of upconversion nanocrystals as biomarkers have been manifested in many important applications, such as highly sensitive molecular detection and autofluorescence-free cell imaging. However, their potential in multiplexed detection and multicolor imaging is rarely exploited, largely owing to the research lagging on multicolor tuning of these particles. Lanthanide doping typically involves an insulating host matrix and a trace amount of lanthanide dopants embedded in the host lattice. The luminescence observed from these doped crystalline materials primarily originates from electronic transitions within the [Xe]4f(n) configuration of the lanthanide dopants. Thus a straightforward approach to tuning the emission is to dope different lanthanide activators in the host lattice. Meanwhile, the host lattice can exert a crystal field around the lanthanide dopants and sometimes may even exchange energy with the dopants. Therefore, the emission can also be modulated by varying the host materials. Recently, the advance in synthetic methods toward high quality core-shell nanocrystals has led to the emergence of new strategies for emission modulation. These strategies rely on precise control over either energy exchange interactions between the dopants or energy transfer involving other optical entities. To provide a set of criteria for future work in this field, we attempt to review general and emerging strategies for tuning emission spectra through lanthanide doping. With significant progress made over the past several years, we now are able to design and fabricate nanoparticles displaying tailorable optical properties. In particular, we show that, by rational control of different combinations of dopants and dopant concentration, a wealth of color output can be generated under single-wavelength excitation. Strikingly, unprecedented single-band emissions can be obtained by careful selection of host matrices. By incorporating a set of lanthanide ions at defined concentrations into different layers of a core-shell structure, the emission spectra of the particles are largely expanded to cover almost the entire visible region, which is hardly accessible by conventional bulk phosphors. Importantly, we demonstrate that an inert-shell coating provides the particles with stable emission against perturbation in surrounding environments, paving the way for their applications in the context of biological networks.

3-Dimensional photonic crystal surface enhanced upconversion emission for improved near-infrared photoresponse

The enhancement of upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is particularly important and highly required for their myriad applications in sensing, photoelectronic devices and bio-imaging. In this work, the amplification of luminescence in NaYF4:Yb/Er and NaYF4:Yb/Tm UCNPs in close proximity to the three-dimensional photonic crystal (3D PC) surface for improved near-infrared photoresponse of a carbon nanotube-based phototransistor is reported. The self-assembled opal 3D PCs with polystyrene sphere sizes of 200, 290 and 360 nm that exhibit reflection peaks of 450, 650 and 800 nm respectively were used for upconversion enhancement, and around 30 times enhancement was obtained for NaYF4:Yb/Er and NaYF4:Yb/Tm UCNPs. Time-resolved upconversion emission and 3D PC transmittance-dependent upconversion enhancement reveal that the enhanced absorption and the extraction effects, resulting from the enhanced non-resonant pump excitation field and the strong coherent scattering provided by 3D PCs respectively, are responsible for the large enhancement. As a proof-of-concept experiment, the prepared 3D PC/NaYF4:Yb/Tm UCNP coupled material layer was introduced into the carbon nanotube-based phototransistor. It is shown that the photoresponsivity of the device to near-infrared light was improved by 10 times with respect to the control device with carbon nanotubes only, which reveals the promising applications of this coupled material in photoelectronic devices such as photovoltaics and other types of phototransistors.

Upconverting and NIR emitting rare earth based nanostructures for NIR-bioimaging

In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln(3+)), nanoscopic host materials doped with Ln(3+), e.g. Y2O3:Er(3+),Yb(3+), are promising candidates for NIR-NIR bioimaging. Ln(3+)-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er(3+),Yb(3+), have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review.

Upconversion-nanophosphor-based functional nanocomposites

Upconversion nanophosphors have the ability to generate visible or near-infrared (NIR) emissions under continuous-wave NIR excitation. Utilizing this special photoluminescent properties, upconversion nanophosphors can be used as key components in complex nanocomposites for a wide range of applications. This review summarizes the basic concept, fabrication strategy, and typical application of upconversion-nanophosphor-based functional nanocomposites. The motivation to design these structures comes from the potential applications in detection, multi-modality bioimaging, and NIR light-induced therapy, as well as the tuning of the upconversion luminescence emissions. This review will give a brief summary of this rapidly developing field, and provide guidance to design and to fabricate new nanocomposites based on upconversion nanophosphors.

Multicolor tunability and upconversion enhancement of fluoride nanoparticles by oxygen dopant

The ability to manipulate the upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is particularly important and highly desired due to their wide applications in color displays, multiplexing bioassays and multicolor imaging. Here, we developed a strategy for simultaneously tuning color output and enhancing upconversion emission of Yb/Er doped fluoride UCNPs, based on adjusting the oxygen doping level. The synthesis of multicolored multifunctional NaGdF4:Yb,Er UCNPs was used as the model host system to demonstrate this protocol. Ammonium nitrate (NH4NO3) was used as the oxygen source and added into the reaction system at the beginning stage of nucleation and growth process of fluoride UCNPs, which facilitates the formation of enough oxygen atoms and the diffusion of these into the fluoride host matrix. The results revealed that multicolour output and upconversion enhancement mainly resulted from the variation of phonon energy and crystal field symmetry of the host lattice, respectively. This strategy can be further expanded to other fluoride host matrices. As an example of an application, multicolored UCNPs were used as a color converter in light emitting diodes, which can effectively convert near-infrared light into visible light. It is expected that these multicolored UCNPs will be promising for applications in multiplexing biodetection, bioimaging (optical and magnetic resonance imaging) and other optical technologies, and the present method for the control of O(2-) doping may also be used in other functional nanomaterials.

Upconversion nanoparticles and their composite nanostructures for biomedical imaging and cancer therapy

Upconversion nanoparticles (UCNPs), particularly lanthanide-doped nanocrystals, which emit high energy photons under excitation by the near-infrared (NIR) light, have found potential applications in many different fields, including biomedicine. Compared with traditional down-conversion fluorescence imaging, the NIR light excited upconversion luminescence (UCL) imaging relying on UCNPs exhibits improved tissue penetration depth, higher photochemical stability, and is free of auto-fluorescence background, which promises biomedical imaging with high sensitivity. On the other hand, the unique upconversion process of UCNPs may be utilized to activate photosensitive therapeutic agents for applications in cancer treatment. Moreover, the integration of UCNPs with other functional nanostructures could result in the obtained nanocomposites having highly enriched functionalities, useful in imaging-guided cancer therapies. This review article will focus on the biomedical imaging and cancer therapy applications of UCNPs and their nanocomposites, and discuss recent advances and future prospects in this emerging field.

High resolution fluorescence imaging of cancers using lanthanide ion-doped upconverting nanocrystals

During the last decade inorganic luminescent nanoparticles that emit visible light under near infrared (NIR) excitation (in the biological window) have played a relevant role for high resolution imaging of cancer. Indeed, semiconductor quantum dots (QDs) and metal nanoparticles, mostly gold nanorods (GNRs), are already commercially available for this purpose. In this work we review the role which is being played by a relatively new class of nanoparticles, based on lanthanide ion doped nanocrystals, to target and image cancer cells using upconversion fluorescence microscopy. These nanoparticles are insulating nanocrystals that are usually doped with small percentages of two different rare earth (lanthanide) ions: The excited donor ions (usually Yb3+ ion) that absorb the NIR excitation and the acceptor ions (usually Er3+, Ho3+ or Tm3+), that are responsible for the emitted visible (or also near infrared) radiation. The higher conversion efficiency of these nanoparticles in respect to those based on QDs and GNRs, as well as the almost independent excitation/emission properties from the particle size, make them particularly promising for fluorescence imaging. The different approaches of these novel nanoparticles devoted to "in vitro" and "in vivo" cancer imaging, selective targeting and treatment are examined in this review.

Combinatorial discovery of lanthanide-doped nanocrystals with spectrally pure upconverted emission

Nanoparticles doped with lanthanide ions exhibit stable and visible luminescence under near-infrared excitation via a process known as upconversion, enabling long-duration, low-background biological imaging. However, the complex, overlapping emission spectra of lanthanide ions can hinder the quantitative imaging of samples labeled with multiple upconverting probes. Here, we use combinatorial screening of multiply doped NaYF(4) nanocrystals to identify a series of doubly and triply doped upconverting nanoparticles that exhibit narrow, spectrally pure emission spectra at various visible wavelengths. We then developed a comprehensive kinetic model validated by our extensive experimental data set. Applying this model, we elucidated the energy transfer mechanisms giving rise to spectrally pure emission. These mechanisms suggest design rules for electronic level structures that yield robust color tuning in lanthanide-doped upconverting nanoparticles. The resulting materials will be useful for background-free multicolor imaging and tracking of biological processes.

Room temperature synthesis of hydrophilic Ln(3+)-doped KGdF4 (Ln = Ce, Eu, Tb, Dy) nanoparticles with controllable size: energy transfer, size-dependent and color-tunable luminescence properties

In this paper, we demonstrate a simple, template-free, reproducible and one-step synthesis of hydrophilic KGdF(4): Ln(3+) (Ln = Ce, Eu, Tb and Dy) nanoparticles (NPs) via a solution-based route at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the samples. The results indicate that the use of water-diethyleneglycol (DEG) solvent mixture as the reaction medium not only allows facile particle size control but also endows the as-prepared samples with good water-solubility. In particular, the mean size of NPs is monotonously reduced with the increase of DEG content, from 215 to 40 nm. The luminescence intensity and absolute quantum yields for KGdF(4): Ce(3+), Tb(3+) NPs increase remarkably with particle sizes ranging from 40 to 215 nm. Additionally, we systematically investigate the magnetic and luminescence properties of KGdF(4): Ln(3+) (Ln = Ce, Eu, Tb and Dy) NPs. They display paramagnetic and superparamagnetic properties with mass magnetic susceptibility values of 1.03 × 10(-4) emu g(-1)·Oe and 3.09 × 10(-3) emu g(-1)·Oe at 300 K and 2 K, respectively, and multicolor emissions due to the energy transfer (ET) process Ce(3+)→ Gd(3+)→ (Gd(3+))(n)→ Ln(3+), in which Gd(3+) ions play an intermediate role in this process. Representatively, it is shown that the energy transfer from Ce(3+) to Tb(3+) occurs mainly via the dipole-quadrupole interaction by comparison of the theoretical calculation and experimental results. This kind of magnetic/luminescent dual-function materials may have promising applications in multiple biolabels and MR imaging.