Open Access

Multifunctional nanoplatforms combine different material properties to meet a wide range of applications, allowing highly customizable systems. In this rapidly advancing research field, we introduce a multifunctional nanomaterial based on the synergy between Tm3+-doped upconverting nanoparticles (UCNPs) and a Cu(I) complex (CuCom). This material is designed for oxygen sensing, optical thermometry, and emission color tuning. In various concentrations, the CuCom complex was electrostatically integrated into a mesoporous silica shell surrounding the core UCNPs (UCNP@mSiO2). The optimized system, UCNP@mSiO2@CuCom-10, was evaluated for different applications. Due to the spectral overlap between the CuCom absorption and the nanoparticles emission, excitation at 980 nm allows most of the UV-blue emission output from the UCNPs to be transferred to the CuCom via luminescent resonance energy transfer (LRET), producing red emission from the molecule. The remaining Tm3+ emission enables optical thermometry, while CuCom’s sensitivity to molecular oxygen supports its application in gas sensing. In upconversion mode, the nanoplatform achieved a Stern−Volmer constant for O2 sensing of 1.64 and demonstrated thermometric relative sensitivities of 0.9% and 1% K−1 at room temperature, with a linear response from 193 to 373 K. Additionally, the emission color of UCNP@mSiO2@CuCom-10 can be tuned from blue to white and yellow, by varying the excitation and temperature, adding further functionality to the system. This multifunctional platform suggests promising applications in biology, medicine, and environmental 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.

Abstract The incorporation of bioactive agents into resin-modified glass ionomer cement (RMGIC) is a promising strategy to improve its mechanical strength and biofilm control, especially for patients with active dental caries. Objective This study aimed to evaluate the effects of incorporating ZnONPs and CaGP into RMGIC on its mechanical and microbiological properties. Design Six groups were tested: 1) RMGIC (without CaGP/ZnONPs); 2) RMGIC-1.0%ZnONPs; 3) RMGIC-2.0%ZnONPs; 4) RMGIC-3.0%CaGP; 5) RMGIC-3.0%CaGP-1.0%ZnONPs; and 6) RMGIC-3.0%CaGP-2.0%ZnONPs. The compressive strength (CS), diametral tensile strength (DTS), and surface hardness (SH) were evaluated after 24 hours and 7 days. Antimicrobial and antibiofilm activity were evaluated using agar diffusion and biofilm metabolic activity (XTT) assays. Results After 24 hours, all the groups showed similar DTS values (p0.05), except for RMGIC-3.0%CaGP-1.0%ZnONPs, which showed the highest DTS value (p<0.05). Comparing 24 hours and 7 days, the DTS values of RMGIC-3.0%CaGP-2.0%ZnONPs, RMGIC-3.0%CaGP, and RMGIC-3.0%CaGP-2.0%ZnONPs were similar (p=0.360). After 24 hours, the RMGIC group showed the CS highest value, followed by RMGIC-2.0%ZnONPs (p < 0.05). After 7 days, the RMGIC-3.0%CaGP-1.0%ZnONPs group exhibited the highest CS value, approximately 15% higher than RMGIC (p<0.05). The RMGIC-1.0%ZnONPs group exhibited significantly higher SH at 24 hours (p=0.621). At 7 days, the highest SH value was observed for the RMGIC-3.0%CaGP-1.0%ZnONPs group (p<0.05). Regarding antimicrobial and antibiofilm activity, including results from biofilm metabolism assays, the RMGIC-3.0%CaGP-1.0%ZnONPs group demonstrated the most effective antimicrobial and inhibitory effects (p<0.05). Conclusion This study demonstrated that adding ZnONPs and CaGP to RMGIC enhanced its mechanical and antimicrobial and antibiofilm properties, suggesting enhanced mechanical performance and improved protection against cariogenic biofilms—critical factors for successful restorative treatments. Therefore, the addition of ZnONPs and CaGP is a promising strategy to develop advanced restorative materials that improve clinical outcomes, especially for patients with active dental caries.

Among several applications, versatile upconversion nanoparticles (UCNPs) which can convert lower-energy infrared radiation into higher-energy visible or ultraviolet light, have emerged as one of the most powerful tools in the field of chemical, physical and biological sensing. The use of UCNPs in fluorescent sensors allows non-invasive, highly sensitive, and selective detection methods, which are particularly beneficial in environments requiring minimal interference and high precision for analytes that can range from metal ions to biomolecules. In this lecture, an overview and the state of the art will be given, accompanied by examples of our recent contributions to key areas such as chronic disease diagnostics, bacterial sensing, and multifunctionally responsive nanoplatforms: (1) An Enhanced Luminescence Lateral-Flow Assay (ELLA) designed for rapid (< 15 min) and early detection of acute kidney injury biomarkers in urine samples, using a commercial cell phone camera, will be presented. The platform is based on Er³⁺- and Tm³⁺-doped UCNPs whose emissions intensities are 40-fold enhanced by an Au-coated mesoporous silica shell, enabling the accurate detection of KIM-1 and NGAL biomarkers with detection limits as low as 0.23 ng/mL; (2) Also, a multifunctional nanoplatform that combines Tm³⁺-doped UCNPs with a Cu(I) complex for applications in oxygen sensing, optical thermometry, and emission colour tuning will be presented. The platform utilizes Luminescent Resonance Energy Transfer (LRET) to achieve efficient energy transfer, enabling red emission from the Cu(I) complex while allowing the use of the UCNP’s original emissions for thermometry. The dual functionality allows sensitive O2 detection and temperature measurements, with relative sensitivities of up to 1% K⁻¹; (3) The critical challenge of rapid bacterial detection and differentiation was addressed by the development of a novel UCNP-based sensor. By functionalizing UCNPs with the antibiotics - vancomycin for Gram-(+) and polymyxin-B for Gram-(-), and using Au nanoparticles as intensity quenchers, the sensor leverages a ratiometric "turn-on" mechanism for selective detection of the bacteria, through changes in the green/red (G/R) ratio for Er-UCNP@PEG4-Van, and blue/red (B/R) ratio for Tm-UCNP@PEG4-Poly. By this approach, differentiation was possible over a wide concentration range of bacteria (0.05 to 5 x 105 CFU/mL) with high correlation with actual bacterial counts (r = 0.99 for S. aureus, r = 0.91 for E. coli); (4) Recently, we have demonstrated a water dispersable ratiometric pH-nanosensor based on host-guest interaction of Tm3+/Yb3+ co-doped UCNPs functionalized with b-cyclodextrin (b-CD) and a pH-responsive nitrobenzoxadiazol dye modified with adamantane (NBD-Ad). The sensor shows a ratiometric emission response (blue/red) over a pH range of 8.0 – 11.0 with high reproducibility, excellent reusability and selectivity, even in the presence of interferents. Together, the presented examples highlight the versatility and potential of UCNPs to develop novel sensors, offering measurable advances in diagnostics, environmental monitoring, and beyond.