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Determination of high-temperature radiative properties of porous silica by combined image analysis, infrared spectroscopy and numerical simulation
摘要： The influence of the texture of fused silica glasses ? containing unconnected spherical bubbles ? on their thermal radiative properties was investigated by combining experimental measurements and numerical simulations. Exact numerical replicas of the porous samples were obtained from X-ray microtomography and image analysis showed that their bubble populations include two lognormal distributions of radii. The complex refractive index of the silica matrix was extracted from emittance measurements acquired at 1200 K on two reference silica samples. The comparison between direct measurements of the normal spectral emittance of the porous samples and those generated by applying Monte-Carlo ray tracing, performed on the numerical replicas, validated the use of geometric optics. The OH content of the porous samples was evaluated to be around 210 ppm. Ray tracing simulations carried out on a set of virtual samples having a similar texture proved to be a flexible means to address experimental limits when characterizing semi-transparent materials. The simulations also provided a natural framework to test the ability of the modified two-flux approximation model to predict the thermal radiative response of the porous silica investigated.
关键词： Radiative properties,X-ray microtomography,Porous silica glass,Spectral emittance,Monte-Carlo ray tracing
更新于2025-09-23 15:23:52
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Amine-functionalized, porous silica-coated NaYF4:Yb/Er upconversion nanophosphors for efficient delivery of doxorubicin and curcumin
摘要： Upconversion nanoparticles (UCNP) with unique multi-photon excitation photo-luminescence properties have been extensively explored as novel contrast agents for low-background biomedical imaging. There is an increasing interest in employing UCNPs as carrier for drug delivery as these offers a unique opportunity to combine therapy and diagnostics in one platform (theranostics). In the present work, we report microwave-assisted synthesis of hexagonal NaYF4:Yb/Er UCNPs coated with porous silica and functionalized with amine (UCNP@mSiO2). The UCNP@mSiO2 were investigated for controlled delivery of a chemotherapeutic agent, doxorubicin (DOX, hydrophilic), and a chemosensitizing agent, curcumin (CCM, hydrophobic). The drug loading was relatively higher for DOX (17.4%), in comparison to CCM (8.1%). The cumulative drug release from DOX-loaded UCNP@mSiO2 were 30 and 41% at physiological (7.4) and tumoral (6.4) pH, following a pseudo Fickian release pattern, whereas the release from CCM-loaded UCNP@mSiO2 were 27 and 50% at pH 7.4 and 6.4, following a non-Fickian and pseudo-Fickian release patterns. Both DOX and CCM-loaded UCNP@mSiO2 exhibited pH-dependent controlled drug delivery but the effect was more pronounced for CCM, the hydrophobic chemosensitizer. Cell viability assay using HeLa cells showed that DOX-loaded UCNP@mSiO2 inhibit cell growth in a dose-dependent manner, similar to free DOX, but the cell inhibition activity of free CCM was lower than CCM passively entrapped in UCNP@mSiO2. Confocal microscopy studies revealed cell uptake of both the drug by HeLa cells. Thus, UCNP@mSiO2 exhibited the unique capability to deliver hydrophilic and hydrophobic drugs, individually. UCNP@mSiO2 carrier, equipped with theranostic capabilities, may potentially be used for pH-responsive release of chemotherapeutic agents in cancer environment.
关键词： curcumin,porous silica,doxorubicin,drug delivery,Upconversion nanoparticles
更新于2025-09-23 15:21:01
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Preparation of triplea??responsive porous silica carriers and carbon quantum dots for photodynamica??chemo therapy and cell multicolor imaging
摘要： Photosensitive carbon quantum dots (CQDs) provide a new route to treat cancer owing to their ability to produce singlet oxygen. In this paper, pH/redox/enzyme-responsive porous silica-based carriers with CQDs were constructed for photodynamic-chemical combination therapy. Porous silica (pSiO2) sample presents uniform sphere with center-radial channels, which is favorable for drug loading and delivery. The CQDs with size of 2.5 nm were synthesized and have the excellent ability to generate singlet oxygen. After loading CQDs and drug molecules, the channels of pSiO2 carrier were blocked with hyaluronic acid (HA)/chitosan (CHI) layer. The disulfide bonds conjugating HA to the surface of pSiO2 carrier would achieve redox-responsive drug release while breaking disulfide bonds and HA/CHI layer could endow the pSiO2 carrier enzyme/pH responsive drug release. The prepared pSiO2 carriers display low cytotoxicity and good biocompatibility for multicolor imaging and photodynamic-chemo therapy.
关键词： CQDs,photodynamic-chemical combination therapy,controlling release,porous silica
更新于2025-09-23 15:19:57