Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in versatile bioapplications. For the first time, organosilica-shelled β-NaLuF₄:Gd/Yb/Er nanoprobes with a rattle structure have been designed for dual-modal imaging and photodynamic therapy (PDT). Benefiting from the unique rattle structure and aromatic framework, these nanoprobes are endowed with a high loading capacity and the disaggregation effect of photosensitizers. After loading of β-carboxyphthalocyanine zinc or rose Bengal into the nanoprobes, we achieved higher energy transfer efficiency from UCNPs to photosensitizers as compared to those with conventional core–shell structure or with pure-silica shell, which facilitates a large production of singlet oxygen and thus an enhanced PDT efficacy. We demonstrated the use of these nanoprobes in proof-of-concept X-ray computed tomography (CT) and UC imaging, thus revealing the great potential of this multifunctional material as an excellent nanoplatform for cancer theranostics.

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in versatile bioapplications. For the first time, organosilica-shelled β-NaLuF₄:Gd/Yb/Er nanoprobes with a rattle structure have been designed for dual-modal imaging and photodynamic therapy (PDT). Benefiting from the unique rattle structure and aromatic framework, these nanoprobes are endowed with a high loading capacity and the disaggregation effect of photosensitizers. After loading of β-carboxyphthalocyanine zinc or rose Bengal into the nanoprobes, we achieved higher energy transfer efficiency from UCNPs to photosensitizers as compared to those with conventional core–shell structure or with pure-silica shell, which facilitates a large production of singlet oxygen and thus an enhanced PDT efficacy. We demonstrated the use of these nanoprobes in proof-of-concept X-ray computed tomography (CT) and UC imaging, thus revealing the great potential of this multifunctional material as an excellent nanoplatform for cancer theranostics.

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in bioapplications. Exploring new host materials to realize efficient upconversion luminescence (UCL) output is a goal of general concern. Herein, we develop a unique strategy for the synthesis of novel LiLuF₄:Ln³⁺ core/shell UCNPs with typically high absolute upconversion quantum yields of 5.0 % and 7.6 % for Er³⁺ and Tm³⁺, respectively. Based on our customized UCL biodetection system, we demonstrate for the first time the application of LiLuF₄:Ln³⁺ core/shell UCNPs as sensitive UCL bioprobes for the detection of an important disease marker β subunit of human chorionic gonadotropin (β-hCG) with a detection limit of 3.8 ng mL⁻¹, which is comparable to the β-hCG level in the serum of normal humans. Furthermore, we use these UCNPs in proof-of-concept computed tomography imaging and UCL imaging of cancer cells, thus revealing the great potential of LiLuF₄:Ln³⁺ UCNPs as efficient nano-bioprobes in disease diagnosis.

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in bioapplications. Exploring new host materials to realize efficient upconversion luminescence (UCL) output is a goal of general concern. Herein, we develop a unique strategy for the synthesis of novel LiLuF₄:Ln³⁺ core/shell UCNPs with typically high absolute upconversion quantum yields of 5.0 % and 7.6 % for Er³⁺ and Tm³⁺, respectively. Based on our customized UCL biodetection system, we demonstrate for the first time the application of LiLuF₄:Ln³⁺ core/shell UCNPs as sensitive UCL bioprobes for the detection of an important disease marker β subunit of human chorionic gonadotropin (β-hCG) with a detection limit of 3.8 ng mL⁻¹, which is comparable to the β-hCG level in the serum of normal humans. Furthermore, we use these UCNPs in proof-of-concept computed tomography imaging and UCL imaging of cancer cells, thus revealing the great potential of LiLuF₄:Ln³⁺ UCNPs as efficient nano-bioprobes in disease diagnosis.

Conventional dissociation-enhanced lanthanide fluoroimmunoassays (DELFIA) using molecular probes suffer from a low labeling ratio of lanthanide ions (Ln³⁺) per biomolecule. Herein, we develop a unique bioassay based on the dissolution-enhanced luminescence of inorganic lanthanide nanoparticles (NPs). As a result of the highly concentrated Ln³⁺ ions in a single Ln³⁺ NP, an extremely high Ln³⁺ labeling ratio can be achieved, which amplifies significantly the luminescence signal and thus improves the detection sensitivity compared to DELFIA. Utilizing sub-10 nm NaEuF₄ NPs as dissolution-enhanced luminescent nanoprobes, we demonstrate the successful in vitro detection of carcinoembryonic antigen (CEA, an important tumor marker) in human serum samples with a record-low detection limit of 0.1 pg mL⁻¹ (0.5 fM). This value is an improvement of approximately 3 orders of magnitude relative to that of DELFIA. The dissolution-enhanced luminescent bioassay shows great promise in versatile bioapplications, such as ultrasensitive and multiplexed in vitro detection of disease markers in clinical diagnosis.

Multimodal bioprobes, which integrate the advantages of different diagnostic modes into one single particle, can overcome the current limitations of sensitivity and resolution in medical assays and significantly improve the outcome of existing therapeutics. Lanthanide-doped inorganic multimodal bioprobes, which are emerging as a promising new class of optical/magnetic multimodal bioprobes, have been long sought-after and have recently attracted revived interest owing to their distinct optical and magnetic properties. In this concept article, we introduce the controlled synthesis of lanthanide-doped inorganic multimodal bioprobes, including core–shell structured and single-phase nanoparticles, and demonstrate different design strategies for achieving dual-modal functionalization of nanoprobes. In particular, we highlight the most recent advances in biodetection, bioimaging, targeted drug delivery, and therapy based on these nanoparticles.