Red-Emitting Latex Nanoparticles by Stepwise Entrapment of β-Diketonate Europium Complexes

The core-shell structure of poly(St-co-MAA) nanoparticles containing β-diketonate Eu³⁺ complexes were synthesized by a step-wise process. The β-diketonate Eu³⁺ complexes of Eu (TFTB)₂(MAA)P(Oct)₃ [europium (III); 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione = TFTB; trioctylphosphine = (P(Oct)₃); methacrylic acid = MAA] were incorporated to poly(St-co-MAA). The poly(St-co-MAA) has highly monodispersed with a size of 300 nm, and surface charges of the poly(St-co-MAA) are near to neutral. The narrow particle size distribution was due to the constant ionic strength of the polymerization medium. The activated carboxylic acid of poly(St-co-MAA) further chelated with europium complex and polymerize between acrylic groups of poly(St-co-MAA) and Eu(TFTB)₂(MAA)P(Oct)₃. The E_m spectra of europium complexes consist of multiple bands of E_m at 585, 597, 612 and 650 nm, which are assigned to ⁵D₀→⁷F_{J (J = 0-3)} transitions of Eu³⁺, respectively. The maximum E_m peak is at 621 nm, which indicates a strong red E_m characteristic associated with the electric dipole ⁵D₀→⁷F₂ transition of Eu³⁺ complexes. The cell-specific fluorescence of Eu(TFTB)₂(MAA)P(Oct)₃@poly(St-co-MAA) indicated endocytosis of Eu(TFTB)₂(MAA)P(Oct)₃@poly(St-co-MAA). There are fewer early apoptotic, late apoptotic and necrotic cells in each sample compared with live cells, regardless of the culture period. Eu(TFTB)₂(MAA)P(Oct)₃@poly(St-co-MAA) synthesized in this work can be excited in the full UV range with a maximum E_m at 619 nm. Moreover, these particles can substitute red luminescent organic dyes for intracellular trafficking and cellular imaging agents.

Self-Assembly of Small Organic Molecules into Luminophores for Cancer Theranostic Applications

Self-assembled biomaterials have been widely explored for real-time fluorescence imaging, imaging-guided surgery, and targeted therapy for tumors, etc. In particular, small molecule-based self-assembly has been established as a reliable strategy for cancer theranostics due to the merits of small-sized molecules, multiple functions, and ease of synthesis and modification. In this review, we first briefly introduce the supramolecular chemistry of small organic molecules in cancer theranostics. Then, we summarize and discuss advanced small molecule-based self-assembly for cancer theranostics based on three types, including peptides, amphiphilic molecules, and aggregation-induced emission luminogens. Finally, we conclude with a perspective on future developments of small molecule-based self-assembled biomaterials integrating diagnosis and therapy for biomedical applications. These applications highlight the opportunities arising from the rational design of small organic molecules with self-assembly properties for precision medicine.

Enhancing Hybrid Upconversion Nanosystems via Synergistic Effects of Moiety Engineered NIR Dyes

Hybrid upconversion nanosystems have been reported to improve the low absorption efficiency of lanthanide-doped upconversion nanoparticles (UCNPs). However, the low quantum yield and poor photostability of NIR dyes pose challenges for practical uses. Here, we introduce a bulky moiety, 4-(1,2,2-triphenylvinyl)-1,1'-biphenyl (TPEO), to enhance its quantum yield by suppressing the bond rotation and improve the stability by deactivating the photoinduced oxidization. Compared with the conventional IR806, the formed NIR dye, TPEO-Cy, has been characterized to deliver three times higher quantum yield and seven times better photostability. Moreover, we take advantage of the strong affinity of sulfonate chains on the TPEO-Cy to bind to the surface of UCNPs. Taking together the synergistic effect, we have achieved a 242-fold upconversion emission enhancement over the benchmark of IR806-sensitized system and an ∼800 000-fold increase than the bare UCNPs. Our design of the NIR dyes suggests a new scope to search for more efficient upconversion nanohybrids.

Luminescence approaches for the rapid detection of disease-related receptor proteins using transition metal-based probes

Protein biomarkers, particularly abnormally expressed receptor proteins, have been proved to be one of the crucial biomarkers for the rapid assessment, diagnosis, prognosis and prediction of specific human diseases. Transition metal based strategies in particular possess delightful strengths in the in-field and real-time visualization of receptor proteins owing to their unique photophysical properties. In this review, we highlight recent advances in the development of detection methods for receptor protein biomarkers using transition metal based approaches, particularly those employing transition metal complexes. We first discuss the strengths and weaknesses of various strategies used for protein biomarker monitoring in live cells. We then describe the principles of the various sensing platforms and their application for receptor protein detection. Finally, we discuss the challenges and future inspirations in this specific field.