Porous hydroxyapatite (HAp) composite fibers functionalized with up-conversion (UC) luminescent and magnetic Na(Y/Gd)F4:Yb3+,Er3+ nanocrystals (NCs) have been fabricated via electrospinning. After transferring hydrophobic oleic acid-capped Na(Y/Gd)F4:Yb3+,Er3+ NCs into aqueous solution, these water-dispersible NCs were dispersed into precursor electrospun solution containing CTAB. Na(Y/Gd)F4:Yb3+,Er3+@HAp composite fibers were fabricated by the high temperature treatment of the electrospun Na(Y/Gd)F4:Yb3+,Er3+ NCs decorated precursor fibers. The biocompatibility test on MC 3T3-E1 cells using MTT assay shows that the HAp composite fibers have negligible cytotoxity, which reveals the HAp composite fibers could be a drug carrier for drug delivery. Because the contrast brightening is enhanced at increased concentrations of Gd3+, the HAp composite fibers can serve as T1 magnetic resonance imaging contrast agents. In addition, the composites uptaken by MC 3T3-E1 cells present the UC luminescent emission of Er3+ under the excitation of a 980 nm near-infrared laser. The above findings reveal Na(Y/Gd)F4:Yb3+,Er3+@HAp composite fibers have potential applications in drug storage/release and magnetic resonance/UC luminescence imaging.

808 nm-light-excited lanthanide (Ln3+)-doped nanoparticles (LnNPs) hold great promise for a wide range of applications, including bioimaging diagnosis and anticancer therapy. This is due to their unique properties, including their minimized overheating effect, improved penetration depth, relatively high quantum yields, and other common features of LnNPs. In this review, the progress of 808 nm-excited LnNPs is reported, including their i) luminescence mechanism, ii) luminescence enhancement, iii) color tuning, iv) diagnostic and v) therapeutic applications. Finally, the future outlook and challenges of 808 nm-excited LnNPs are presented.

In recent years, near-infrared (NIR) light, as a powerful means of external stimulus, has attracted widespread attention in the field of tumor research. On one hand, NIR light-excited rare earth upconversion nanoparticles (UCNPs) have presented unique features in multimodal bioimaging, energy conversion and photocontrolled drug delivery. On the other hand, NIR-light-triggered photothermal therapy (PTT) is a minimally invasive approach in the fight against tumors, owing to its high spatial resolution, economic viability and improved target selectivity. Thus, the marrying of UCNPs and NIR photothermal agents could open new avenues in the construction of theranostic nanoplatforms. This review primarily focuses on the new advances in the design and the therapeutic applications of multifunctional UCNPs–NIR absorber nanoplatforms. The future challenges and prospects in this field are also addressed.

Near-infrared (NIR) light induced phototherapy has attracted considerable attention due to its deep therapeutic depth. To improve the therapeutic outcome and address non-selective side effects, the combination of complementary phototherapeutic strategies in a single nanoagent with precise targeting ability may provide an effective approach for cancer therapy. Thus we have developed an 808 nm NIR light triggered nanosystem based on IR806 dye functionalized MnFe2O4 (MFO-IR) for synchronous magnetic targeted and magnetic resonance (MR) imaging guided in vivo photodynamic/photothermal synergistic therapy. In this construction strategy, carboxylic acid functionalized NIR dye IR806 is explored as an 808 nm NIR-excited photosensitizer (PS) for the first time, which can also provide a conjugation site for MnFe2O4 nanoparticles (MFO NPs). Here, monodisperse MFO NPs have multiple capacities as dye carriers, targeting ligands, MRI contrast agents and photothermal agents. MFO-IR nanocomposites (NCs) with negligible toxicity present efficient NIR-mediated photothermal damage and ROS cytotoxicity via the relevant in vitro experimental investigations. With ideal magnetic targeting effects and remarkable NIR light-responsive properties, these MFO-IR NCs exhibit high in vivo tumor localization and could destroy subcutaneous solid tumors completely under an external magnetic field and 808 nm laser irradiation. Consequently, this magnetic nanosystem has great potential for simultaneous diagnosis and precise cancer phototherapy.

Combining multi-model treatments within one single system has attracted great interest for the purpose of synergistic therapy. In this paper, hollow gold nanospheres (HAuNs) coated with a temperature-sensitive polymer, poly(oligo(ethylene oxide) methacrylate-co-2-(2-methoxyethoxy)ethyl methacrylate) (p(OEGMA-co-MEMA)), co-loaded with DOX and a photosensitizer Chlorin e6 (Ce6) were successfully synthesized. As high as 58% DOX and 6% Ce6 by weight could be loaded onto the HAuNs-p(OEGMA-co-MEMA) nanocomposites. The grafting polymer brushes outside the HAuNs play the role of “gate molecules” for controlled drug release by 650 nm laser radiation owing to the temperature-sensitive property of the polymer and the photothermal effect of HAuNs. The HAuNs-p(OEGMA-co-MEMA)-Ce6-DOX nanocomposites with 650 nm laser radiation show effective inhibition of cancer cells in vitro and enhanced anti-tumor efficacy in vivo. In contrast, control groups without laser radiation show little cytotoxicity. The nanocomposite demonstrates a way of “killing three birds with one stone”, that is, chemotherapy, photothermal and photodynamic therapy are triggered simultaneously by the 650 nm laser stimulation. Therefore, the nanocomposites show the great advantages of multi-modal synergistic effects for cancer therapy by a remote-controlled laser stimulus.

A nanocomposite fabricated by electrostatic spinning, which incorporated polyaniline nanoparticles into poly(ε-caprolactone) and gelatin (PG), was used to form nanofiber fabrics. Polyaniline nanoparticles have a strong optical absorption at near-infrared (NIR) wavelengths and can convert optical energy into thermal energy under 808 nm laser irradiation, allowing them to ablate tumor cells thermally. Pieces of the nanocomposite were surgically implanted into tumors in mice, and orthotopic photothermal therapy was performed. The experimental results in vivo suggested that polyaniline PG can inhibit tumor growth efficiently by converting optical energy into thermal energy to ablate tumor cells.

Eu3+ and/or Tb3+-doped CaGdAlO4 phosphor samples were synthesized via a conventional high temperature solid-state reaction process. X-Ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) as well as cathodoluminescence (CL) spectra were used to characterize the samples. For CaGdAlO4:Tb3+, the concentration of doped Tb3+ has a significant effect on the 5D3/5D4 emission intensity due to the dipole–dipole cross-relaxation mechanism from 5D3 to 5D4. Under the 4f8 → 4f75d excitation of Tb3+ or low-voltage electron beam excitation, the CaGdAlO4:Tb3+ samples show tunable luminescence from blue to cyan and then to green with the variation of the Tb3+-doping concentration. For CaGdAlO4:Eu3+, the samples exhibit a reddish-orange emission corresponding to the 5D0,1 → 7F0,1,2,3 transitions of Eu3+. Energy transfer can take place from Tb3+ to Eu3+ when they are codoped in one host. Furthermore, for CaGdAlO4:Tb3+/Eu3+, a white emission can be realized in the single phase CaGdAlO4 host by reasonably adjusting the doping concentrations of Tb3+ and Eu3+ under low-voltage electron beam excitation. Due to the excellent PL, CL properties and good CIE chromaticity coordinates, the as-prepared Tb3+/Eu3+-doped CaGdAlO4 nanocrystalline phosphors have potential applications in field emission display devices.

In this paper, well defined GdOF:Yb3+/Er3+, Tm3+, Ho3+ nano/submicrocrystals with multiform morphologies were prepared via the urea-based precipitation method without using any surfactants. The morphologies of the GdOF products, including spindles and spheres with different sizes (30–550 nm), could be easily modulated by changing the fluorine sources, and the possible formation mechanism has been presented. XRD, FT-IR, SEM, TEM, as well as up-conversion (UC) photoluminescence spectra were used to characterize the prepared samples. Under 980 nm NIR excitation, the relative emission intensities and emission colors of Yb3+/Er3+, Yb3+/Tm3+ and Yb3+/Ho3+ doped GdOF could be precisely adjusted over a wide range by tuning the Yb3+ doping concentration. The strategies for color tuning of UC emission proposed in the current system may be helpful to achieve efficient multicolor luminescence under 980 nm laser excitation. In addition, the corresponding UC mechanisms in the co-doping GdOF systems were analyzed in detail based on the emission spectra and the plot of luminescence intensity to pump power.

Porous hydroxyapatite (HAp) composite fibers functionalized with up-conversion (UC) luminescent and magnetic Na(Y/Gd)F4:Yb3+,Er3+ nanocrystals (NCs) have been fabricated via electrospinning. After transferring hydrophobic oleic acid-capped Na(Y/Gd)F4:Yb3+,Er3+ NCs into aqueous solution, these water-dispersible NCs were dispersed into precursor electrospun solution containing CTAB. Na(Y/Gd)F4:Yb3+,Er3+@HAp composite fibers were fabricated by the high temperature treatment of the electrospun Na(Y/Gd)F4:Yb3+,Er3+ NCs decorated precursor fibers. The biocompatibility test on MC 3T3-E1 cells using MTT assay shows that the HAp composite fibers have negligible cytotoxity, which reveals the HAp composite fibers could be a drug carrier for drug delivery. Because the contrast brightening is enhanced at increased concentrations of Gd3+, the HAp composite fibers can serve as T1 magnetic resonance imaging contrast agents. In addition, the composites uptaken by MC 3T3-E1 cells present the UC luminescent emission of Er3+ under the excitation of a 980 nm near-infrared laser. The above findings reveal Na(Y/Gd)F4:Yb3+,Er3+@HAp composite fibers have potential applications in drug storage/release and magnetic resonance/UC luminescence imaging.

Eu3+ and/or Tb3+-doped CaGdAlO4 phosphor samples were synthesized via a conventional high temperature solid-state reaction process. X-Ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) as well as cathodoluminescence (CL) spectra were used to characterize the samples. For CaGdAlO4:Tb3+, the concentration of doped Tb3+ has a significant effect on the 5D3/5D4 emission intensity due to the dipole–dipole cross-relaxation mechanism from 5D3 to 5D4. Under the 4f8 → 4f75d excitation of Tb3+ or low-voltage electron beam excitation, the CaGdAlO4:Tb3+ samples show tunable luminescence from blue to cyan and then to green with the variation of the Tb3+-doping concentration. For CaGdAlO4:Eu3+, the samples exhibit a reddish-orange emission corresponding to the 5D0,1 → 7F0,1,2,3 transitions of Eu3+. Energy transfer can take place from Tb3+ to Eu3+ when they are codoped in one host. Furthermore, for CaGdAlO4:Tb3+/Eu3+, a white emission can be realized in the single phase CaGdAlO4 host by reasonably adjusting the doping concentrations of Tb3+ and Eu3+ under low-voltage electron beam excitation. Due to the excellent PL, CL properties and good CIE chromaticity coordinates, the as-prepared Tb3+/Eu3+-doped CaGdAlO4 nanocrystalline phosphors have potential applications in field emission display devices.

In recent years, near-infrared (NIR) light, as a powerful means of external stimulus, has attracted widespread attention in the field of tumor research. On one hand, NIR light-excited rare earth upconversion nanoparticles (UCNPs) have presented unique features in multimodal bioimaging, energy conversion and photocontrolled drug delivery. On the other hand, NIR-light-triggered photothermal therapy (PTT) is a minimally invasive approach in the fight against tumors, owing to its high spatial resolution, economic viability and improved target selectivity. Thus, the marrying of UCNPs and NIR photothermal agents could open new avenues in the construction of theranostic nanoplatforms. This review primarily focuses on the new advances in the design and the therapeutic applications of multifunctional UCNPs–NIR absorber nanoplatforms. The future challenges and prospects in this field are also addressed.

Near-infrared (NIR) light induced phototherapy has attracted considerable attention due to its deep therapeutic depth. To improve the therapeutic outcome and address non-selective side effects, the combination of complementary phototherapeutic strategies in a single nanoagent with precise targeting ability may provide an effective approach for cancer therapy. Thus we have developed an 808 nm NIR light triggered nanosystem based on IR806 dye functionalized MnFe2O4 (MFO-IR) for synchronous magnetic targeted and magnetic resonance (MR) imaging guided in vivo photodynamic/photothermal synergistic therapy. In this construction strategy, carboxylic acid functionalized NIR dye IR806 is explored as an 808 nm NIR-excited photosensitizer (PS) for the first time, which can also provide a conjugation site for MnFe2O4 nanoparticles (MFO NPs). Here, monodisperse MFO NPs have multiple capacities as dye carriers, targeting ligands, MRI contrast agents and photothermal agents. MFO-IR nanocomposites (NCs) with negligible toxicity present efficient NIR-mediated photothermal damage and ROS cytotoxicity via the relevant in vitro experimental investigations. With ideal magnetic targeting effects and remarkable NIR light-responsive properties, these MFO-IR NCs exhibit high in vivo tumor localization and could destroy subcutaneous solid tumors completely under an external magnetic field and 808 nm laser irradiation. Consequently, this magnetic nanosystem has great potential for simultaneous diagnosis and precise cancer phototherapy.