Upconverting Nanoparticle-based Enhanced Luminescence Lateral-Flow Assay for Urinary Biomarker Monitoring.

Development of efficient portable sensors for accurately detecting biomarkers is crucial for early disease diagnosis, yet remains a significant challenge. To address this need, we introduce the enhanced luminescence lateral-flow assay, which leverages highly luminescent upconverting nanoparticles (UCNPs) alongside a portable reader and a smartphone app. The sensor's efficiency and versatility were shown for kidney health monitoring as a proof of concept. We engineered Er3+- and Tm3+-doped UCNPs coated with multiple layers, including an undoped inert matrix shell, a mesoporous silica shell, and an outer layer of gold (UCNP@mSiO2@Au). These coatings synergistically enhance emission by over 40-fold and facilitate biomolecule conjugation, rendering UCNP@mSiO2@Au easy to use and suitable for a broad range of bioapplications. Employing these optimized nanoparticles in lateral-flow assays, we successfully detected two acute kidney injury-related biomarkers─kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)─in urine samples. Using our sensor platform, KIM-1 and NGAL can be accurately detected and quantified within the range of 0.1 to 20 ng/mL, boasting impressively low limits of detection at 0.28 and 0.23 ng/mL, respectively. Validating our approach, we analyzed clinical urine samples, achieving biomarker concentrations that closely correlated with results obtained via ELISA. Importantly, our system enables biomarker quantification in less than 15 min, underscoring the performance of our novel UCNP-based approach and its potential as reliable, rapid, and user-friendly diagnostics.

Tailoring the structure and self-activated photoluminescence of carbonated amorphous calcium phosphate nanoparticles for bioimaging applications.

Self-activated luminescent calcium phosphate (CaP) nanoparticles, including hydroxyapatite (HA) and amorphous calcium phosphate (ACP), are promising for bioimaging and theragnostic applications in nanomedicine, eliminating the need for activator ions or fluorophores. In this study, we developed luminescent and stable citrate-functionalized carbonated ACP nanoparticles for bioimaging purposes. Our findings revealed that both the CO32- content and the posterior heating step at 400 °C significantly influenced the composition and the structural ordering of the chemically precipitated ACP nanoparticles, impacting the intensity, broadness, and position of the defect-related photoluminescence (PL) emission band. The heat-treated samples also exhibited excitation-dependent PL under excitation wavelengths typically used in bioimaging (λexc = 405, 488, 561, and 640 nm). Citrate functionalization improved the PL intensity of the nanoparticles by inhibiting non-radiative deactivation mechanisms in solution. Additionally, it resulted in an increased colloidal stability and reduced aggregation, high stability of the metastable amorphous phase and the PL emission for at least 96 h in water and supplemented culture medium. MTT assay of HepaRG cells, incubated for 24 and 48 h with the nanoparticles in concentrations ranging from 10 to 320 µg mL-1, evidenced their high biocompatibility. Internalization studies using the nanoparticles self-activated luminescence showed that cellular uptake of the nanoparticles is both time (4-24 h) and concentration (160-320 µg mL-1) dependent. Experiments using confocal laser scanning microscopy allowed the successful imaging of the nanoparticles inside cells via their intrinsic PL after 4 h of incubation. Our results highlight the potential use of citrate-functionalized carbonated ACP nanoparticles for use in internalization assays and bioimaging procedures.

Mesoporous silica nanoparticles incorporated with Ir(III) complexes: From photophysics to photodynamic therapy.

Organically modified mesoporous silica nanoparticles (MSNs) containing Ir complexes (Ir1, Ir2 and Ir3) were successfully synthesized. These Ir-entrapped MCM41-COOH nanoparticles have shown relevant photophysical characteristics including high efficiency in the photoproduction and delivery of singlet oxygen (1O2), which is particularly promising for photodynamic therapy (PDT) applications. In vitro tests have evidenced that complex@MCM41-COOH are able to reduce cell proliferation after 10 min of blue-light irradiation in Hep-G2 liver cancer cells.

Photophysical Properties of Ir(III) Complexes Immobilized in MCM-41 via Templated Synthesis.

In the search for understanding and improving the luminescence of optical materials based on Ir(III) complexes, three [Ir(C∧N)2(dnbp)]+ (dnbp = 4,4'-dinonyl-2,2'-bipyridine) emitters were immobilized in MCM-41 mesoporous nanoparticles. By taking advantage of the amphiphilic nature of [Ir(C∧N)2(dnbp)]+, the complexes were mixed with an appropriate surfactant and the resulting micelles served as templates for the synthesis of mesoporous silica host materials in a one-step sol-gel route. The MCM-encapsulated [Ir(C∧N)2(dnbp)]+ complexes present intense emissions with prominent rigidochromic spectral changes that are substantially less affected by O2 as compared to methanolic solutions, with a thousand-fold decrease in quenching rate constants. These photophysical results points to a possible suitability of Ir(III)-complex-MCM-41 host-guest systems for possible future optoelectronic devices, rigidity optical sensors, or biological markers in different colors.