Boron Polylactide Nanoparticles Exhibiting Fluorescence and Phosphorescence in Aqueous Medium

Pfister, Anne; Zhang, Guoqing; Zareno, Jessica; Horwitz, Alan F.; Fraser, Cassandra L.

doi:10.1021/nn7003525

Cited by 129 publications

(146 citation statements)

References 49 publications

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“…No peak at $17 ppm (enol proton of the diketone) was seen, confirming that the methanol precipitation process did not cleave the boron complex to form a diketone, as BF 2 bdk complexes are conditionally sensitive towards protic solvents. 18 The polymer molecular weight was determined by GPC (M n ¼ 11 900 Da, PDI ¼ 3.80), showing a broad distribution typical of polycondensation/hydrosilylation reactions.…”

Section: Synthesismentioning

confidence: 99%

A mechanistic investigation of mechanochromic luminescent organoboron materials

et al. 2012

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Mechanochromic luminescence (ML) refers to the luminescence color and/or intensity change of solidstate materials induced by mechanical perturbations. For organic molecular solids, this phenomenon is related to the specific packing modes and orientations of individual fluorophores, which could give rise to different excited-state interactions. The molecular solids of difluoroboron dibenzoylmethane (BF 2 dbm) derivatives were previously found to exhibit reversible ML at room temperature and are promising as self-healing optical materials. In this report, we aim to shed some light on the mechanism of BF 2 dbm ML by trying to understand the excited-state interactions among solid-state BF 2 dbm molecules and elucidate how these interactions change upon mechanical stimulation. We first investigated the optical properties of monomeric, dimeric, and polymeric BF 2 dbm derivatives in optically dilute solutions and demonstrated unambiguously that BF 2 dbm moieties have a propensity to form H-aggregates. Next, we studied the physical properties of these boron complexes in the solid state including their crystal structures, fluorescence emissions, and mechanochromic luminescence. By correlating solution data with the solid-state characterization results, it was concluded that two coupled processes, force-induced emissive H-aggregate formation and energy transfer to the emissive Haggregates, are responsible for the observed BF 2 dbm ML in the solid state.

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Section: Synthesismentioning

confidence: 99%

A mechanistic investigation of mechanochromic luminescent organoboron materials

et al. 2012

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“…The dye-polymer conjugate 15 BF 2 dbm(I)PLA and boron nanoparticle aqueous suspensions 16 were fabricated accordingly to previously reported methods at a concentration of 1 mg/ml. Specifically, the polymer was generated by solvent-free lactide ring opening polymerization using the primary alcohol functionalized BF 2 dbm(I)OH initiator and tin octoate as the catalyst.…”

Section: Bnp Preparationmentioning

confidence: 99%

“…• C) in these PLA biomaterials, even as BNPs in aqueous environments, 16 which makes them useful for O 2 sensing via a dynamic quenching mechanism. Many pO 2 sensors are based on lifetime (τ ), because τ is a concentration-independent variable, but its measurement requires specialized instrumentation not typically present in routine fluorescence detection systems.…”

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confidence: 99%

Optical imaging of tumor hypoxia dynamics

et al. 2010

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Abstract. The influence of the tumor microenvironment and hypoxia plays a significant role in determining cancer progression, treatment response, and treatment resistance. That the tumor microenvironment is highly heterogeneous with significant intratumor and intertumor variability presents a significant challenge in developing effective cancer therapies. Critical to understanding the role of the tumor microenvironment is the ability to dynamically quantify oxygen levels in the vasculature and tissue in order to elucidate the roles of oxygen supply and consumption, spatially and temporally. To this end, we describe the use of hyperspectral imaging to characterize hemoglobin absorption to quantify hemoglobin content and oxygen saturation, as well as dual emissive fluorescent/phosphorescent boron nanoparticles, which serve as ratiometric indicators of tissue oxygen tension. Applying these techniques to a window-chamber tumor model illustrates the role of fluctuations in hemoglobin saturation in driving changes in tissue oxygenation, the two being significantly correlated (r = 0.77). Finally, a green-fluorescence-protein reporter for hypoxia inducible factor-1 (HIF-1) provides an endpoint for hypoxic stress in the tumor, which is used to demonstrate a significant association between tumor hypoxia dynamics and HIF-1 activity in an in vivo demonstration of the technique. Tumor hypoxia plays an important role in cancer progression, metastasis, and the effectiveness of therapies.1-3 It is a highly dynamic process and the temporal dynamics can play a significant role in treatment resistance and tumor aggressiveness. 2,4-10A recent trend in therapeutic strategies is to target tumor angiogenesis in order to modify the microenvironment and make tumors more sensitive to conventional therapies.11 The ability to measure pO 2 and image tumor hypoxia on the microscopic level is essential to further understanding microenvironmental factors and modifying therapies, depending on treatment response. Characterizing the local microenvironment, particularly hypoxia, longitudinally, on a microscopic scale would be ideal. This is a challenging problem, however, and one for which no established imaging technique exists. Many methods have been developed that range from histological staining with reducible nitroimidazole reagents, protein markers, and green fluorescence protein (GFP) or luciferase reporter genes, to electrochemical probe methods, and optical, nuclear medicine, and magnetic resonance techniques 12 although some methods are only suitable for the laboratory, others have been translated into the clinic, and all have their advantages and drawbacks. 13,14 The key point is that there is no easily implemented technique for imaging vascular oxygenation (hemoglobin oxygenation) in combination with tissue oxygen tension on the microcirculatory level. We present an approach based on hyperspectral imaging of hemoglobin absorption and dual emissive boron nanoparticles (BNPs). The combination of these techniques enables quantification of...

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“…The dual-emissive aromatic ketone selected in this study is N,Nhydroxyethylamino benzophenone (K1) which is stable in aqueous and ambient conditions, whereas previous boron dyes have shown partial degradation over time. 26,27 The synthesis and optical characterization of WPUs containing different ratios of K1 will serve as the main focus of this initial report: we found that the dual emission from these WPUs can be affected by K1 concentrations, which is very well explained by a model 16,28 we recently proposed.…”

Section: ■ Introductionmentioning

confidence: 71%

Waterborne Polyurethanes with Tunable Fluorescence and Room-Temperature Phosphorescence

Zhou

Xie

Zhou

et al. 2015

ACS Appl. Mater. Interfaces

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Single-component materials with both fluorescence and room-temperature phosphorescence (RTP) are useful for ratiometric sensing and imaging applications. On the basis of a general design principle, an amino-substituted benzophenone is covalently incorporated into waterborne polyurethanes (WPU) and results in fluorescence and RTP single-component dual-emissive materials (SDMs). At different aminobenzophenone concentrations, the statistical, thermal, and optical properties of these SDMs are characterized. Despite their similar thermal behaviors, the luminescence properties as a function of the chromophore concentration are quite different: increasing concentrations led to progressively narrowed singlet-triplet energy gaps. The tunability of fluorescence and RTP via chromophore concentration is explained by a previously proposed model, polymerization-enhanced intersystem crossing (PEX). The proposal of PEX is based on Kasha's molecular exciton theory with a specific application in polymeric systems, where the polymerization of luminophores results in excitonic coupling and enhanced forward and reverse intersystem crossing. The mechanism of PEX is also examined by theoretical calculations for the WPU system. It is found that the presence of K1 aggregates indeed enhances the crossover from singlet excited states to triplet ones.

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Boron Polylactide Nanoparticles Exhibiting Fluorescence and Phosphorescence in Aqueous Medium

Cited by 129 publications

References 49 publications

A mechanistic investigation of mechanochromic luminescent organoboron materials

A mechanistic investigation of mechanochromic luminescent organoboron materials

Optical imaging of tumor hypoxia dynamics

Waterborne Polyurethanes with Tunable Fluorescence and Room-Temperature Phosphorescence

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