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Nanoscale ; 2020 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-32373869


Single particle imaging of upconversion nanoparticles (UCNPs) has typically been realized using hexagonal (ß) phase lanthanide-doped sodium yttrium fluoride (NaYF4) materials, the upconversion luminescence (UCL) of which saturates at power densities (P) of several hundred W cm-2 under 980 nm near-infrared (NIR) excitation. Cubic (α) phase UCNPs have been mostly neglected because of their commonly observed lower UCL efficiency at comparable P in ensemble level studies. Here, we describe a set of sub-15 nm ytterbium-enriched α-NaYbF4:Er3+@CaF2 core/shell UCNPs doped with varying Er3+ concentrations (5-25%), studied over a wide P range of ∼8-105 W cm-2, which emit intense UCL even at a low P of 10 W cm-2 and also saturate at relatively low P. The highest upconversion quantum yield (ΦUC) and the highest particle brightness were obtained for an Er3+ dopant concentration of 12%, reaching the highest ΦUC of 0.77% at a saturation power density (Psat) of 110 W cm-2. These 12%Er3+-doped core/shell UCNPs were also the brightest UCNPs among this series under microscopic conditions at high P of ∼102-105 W cm-2 as demonstrated by imaging studies at the single particle level. Our results underline the potential applicability of the described sub-15 nm cubic-phase core/shell UCNPs for ensemble- and single particle-level bioimaging.

Artigo em Inglês | MEDLINE | ID: mdl-31511782


The aim of this study was to examine whether Xuesaitong, a multiherbal formulation for coronary heart disease, alters the pharmacokinetics of losartan. Adult male Sprague Dawley rats randomly received losartan (10 mg/kg) or losartan plus Xuesaitong (10 mg/kg) through an oral gavage (n = 6). Multiple blood samples were obtained for up to 36 h to determine the concentrations of losartan and its active metabolite, EXP3174, through ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Pharmacokinetics were estimated using a noncompartmental model. The half-life (t 1/2) of losartan was decreased by Xuesaitong (4.26 ± 1.51 vs. 6.35 ± 2.10 h; P < 0.05). The apparent volume of distribution (V d) of losartan was also decreased by the combination of losartan and Xuesaitong (4.41 ± 1.61 vs. 7.20 ± 2.41 mL; P < 0.05). The time to maximum concentration (T max) of losartan was increased by Xuesaitong (1.06 ± 1.04 vs. 0.13 ± 0.05 h; P < 0.05). Xuesaitong also decreased the t 1/2 of EXP3174 (8.22 ± 1.41 vs. 6.29 ± 1.38 h; P < 0.05). These results suggest that there is a complex interaction between losartan and Xuesaitong. In addition to enhanced elimination of losartan and EXP3174, Xuesaitong may also decrease the absorption rate and V d of losartan.

Nano Lett ; 17(12): 7487-7493, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29160715


Upon photo- or electrical-excitation, colloidal quantum dots (QDs) are often found in multicarrier states due to multiphoton absorption, photocharging, or imbalanced carrier injection of the QDs. While many of these multicarrier states are observed in single-dot spectroscopy, their properties are not well studied due to random charging/discharging, emission intensity intermittency, and uncontrolled surface defects of single QDs. Here we report in situ deciphering of the charging status, precisely assessing the absorption cross section, and determining the absolute emission quantum yield of monoexciton and biexciton states for neutral, positively charged, and negatively charged single core/shell CdSe/CdS QDs. We uncover very different photon statistics of the three charge states in single QDs and unambiguously identify their charge signs together with the information on their photoluminescence decay dynamics. We then show their distinct photoluminescence saturation behaviors and evaluate the absolute values of absorption cross sections and quantum efficiencies of monoexcitons and biexcitons. We demonstrate that the addition of an extra hole or electron in a QD not only changes its emission properties but also varies its absorption cross section.

Spine J ; 15(1): 71-8, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25011095


BACKGROUND CONTEXT: Surgical treatment of thoracolumbar tuberculosis (TB) aims at spinal cord decompression, focus debridement, spine stability, and deformity correction. However, several problems exist in treating multiple segmental thoracolumbar TB, including reducing surgical trauma with effective incision exposure; ensuring the effective long-armed fixation, and maintaining the possibility for revisionary surgery in cases of treatment failure. PURPOSE: To investigate the clinical efficacy and surgical technique of the single posterior midline approach for screw-rod fixation and debridement through the sacrospinalis muscle outer cross-window to treat multiple segmental thoracolumbar spinal TB. STUDY DESIGN: A retrospective cohort study. PATIENT SAMPLE: A group of 17 patients with spinal TB after surgical treatment, with a mean follow-up of 27.9 months (range, 18-48 months). OUTCOME MEASURES: Neurologic recovery, Cobb angle, and graft union assessed by the Moon standard. METHODS: This study was approved by the local ethical committee and recruited patients from January, 2005 to January, 2011. We used a posterior midline incision for internal fixation of a pedicle screw system in the gap of the longissimus and spinal multifidus. Anterior lesion debridement and interbody fusions were performed through bilateral cross-windows in the outer edge of the sacrospinalis muscle. Using this technique, we treated 17 patients (10 men; aged 19 to 68 years; mean 39.8 years) with spinal TB involving more than four vertebrae. Nerve damage was classified by the Frankel classification. All patients were treated with regular anti-TB chemotherapy and were followed for 18 to 48 (mean: 27.9 months) months. RESULTS: The mean (range) for operative time was 4.7 (3.6-6.3) hours, for blood loss during surgery was 1,100 (850-2,300) mL, and for time of interbody fusion was 6.3 (4 to 11) months. The Cobb angle correction rate is 67.1%. Nine of 11 patients' neurologic function returned to normal, which was statistically significant (p=.004). There was no TB recurrence or internal fixation failure. CONCLUSIONS: Combined with anti-TB chemotherapy, the discussed surgical technique can show improved lesion clearance, decompression of the anterior aspect of the spine, bone graft fusion, internal fixation of outside lesions, drainage and lead to positive treatment outcomes.

Vértebras Lombares/cirurgia , Fusão Vertebral/métodos , Vértebras Torácicas/cirurgia , Tuberculose da Coluna Vertebral/cirurgia , Adulto , Idoso , Transplante Ósseo/métodos , Desbridamento/métodos , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Parafusos Pediculares , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem