Lanthanide-doped fluoride up-converting nanoparticles (UCNPs) represent the new class of imaging contrast agents which hold great potential for overcoming existing problems associated with traditionally used dyes, proteins and quantum dots. In this study, a new kind of hybrid NaYF:Yb,Er/PLGA nanoparticles for efficient biolabeling were prepared through one-pot solvothermal synthesis route. Morphological and structural characteristics of the as-designed particles were obtained using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (SEM/TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy, while their cytotoxicity as well as up-conversion (UC) labeling capability were tested in vitro toward human gingival cells (HGC) and oral squamous cell carcinoma (OSCC). The results revealed coexistence of the cubic (Fm-3m) and hexagonal (P6/m) phase in spherical and irregularly shaped nanoparticles, respectively. PLGA [Poly(lactic-co-glycolic acid)] ligands attached at the surface of UCNPs particles provide their enhanced cellular uptake and enable high-quality cells imaging through a near-infrared (NIR) laser scanning microscopy (λ = 980 nm). Moreover, the fact that NaYF4:Yb,Er/PLGA UCNPs show low cytotoxicity against HGC over the whole concentration range (10-50 μg/mL) while a dose dependent viability of OSCC is obtained indicates that these might be a promising candidates for targeted cancer cell therapy.
The emerging up-conversion nanoparticles (UCNPs) offer a wide range of biotechnology applications, from biomarkers and deep tissue imaging, to single molecule tracking and drug delivery.
Single phase β-NaY 0.8-x Gd x Yb 0.18 Er 0.02 F 4 nanoparticles with different concentrations of gadolinium ions were prepared via PVP-assisted solvothermal treating at 200°C (PVP-polyvinylpyrrolidone). With the increase in Gd 3+ concentration, size of the nanoparticles decreased. The up-converting spectra recorded upon 980 nm irradiation showed the green (510-560 nm) and red (640-690 nm) emissions, due to 2 H 11/2 , 4 S 3/2 → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions, respectively. The strongest up-conversion luminescence was detected in 15 mol% Gd 3+ -doped nanoparticles obtained after 20 hours of solvothermal treating. With the rise of Gd 3+ content up-conversion emission decreased due to increased defect concentration in the NaYF 4 matrix. Fourier transform infrared spectroscopy proved in situ generation of hydrophilic nanoparticles as a result of PVP ligands retention at the particle surface.
U ovom radu razmatran je diverziti sistem sa tri mikrodiverziti SC prijemnika i jednim makrodiverziti SC prijemnikom. Na ulazima u mikrodiverziti SC prijemnike prisutan je nezavisni k-μ feding i korelisani spori Gama feding. Za ovaj model izračunati su gustina verovatnoća signala na izlazu iz mikrodiverziti SC prijemnika i makrodiverziti SC prijemnika. Dobijeni rezultati su grafički prikazani kako bi se pokazao uticaj Rajsovog k faktora, dubine osenčenosti kanala c, broj klastera µ i koeficijenta korelacije ρ na gustinu verovatnoće signala na izlazu iz makrodiverziti sistema.
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