Improved Molecular Imprinting Based on Colloidal Particles Made from Miniemulsion: A Case Study on Testosterone and Its Structural Analogues

© 2016 American Chemical Society. Molecularly imprinted polymers (MIPs) in the micron and submicron scale based on the bifunctional cross-linker N,O-bismethacryloylethanolamine (NOBE) have been synthesized using bulk and miniemulsion polymerization, respectively. MIPs with distinct selectivity for the template testosterone were obtained. Colloidal MIP particles made using the miniemulsion technique have significant advantages compared to bulk MIP counterparts owing to their small size, homogeneity, and increased surface, as is demonstrated by optical batch rebinding studies using a nonimprinted polymer (NIP) as a negative control. Affinity and selectivity studies were also performed with the miniemulsion colloidal MIPs. These MIPs display largely increased imprint factors (6.8 vs 2.2) when compared to their bulk MIP counterparts. Further, selectivity studies by using analogue steroids show that colloidal MIPs also display a higher selectivity. In summary, miniemulsion MIPs show much better performance with respect to molecular recognition in aqueous solution, while providing at the same time the possibility for a water-based MIP synthesis.status: publishe

3D full-field quantification of cell-induced large deformations in fibrillar biomaterials by combining non-rigid image registration with label-free second harmonic generation

To advance our current understanding of cell-matrix mechanics and its importance for biomaterials development, advanced three-dimensional (3D) measurement techniques are necessary. Cell-induced deformations of the surrounding matrix are commonly derived from the displacement of embedded fiducial markers, as part of traction force microscopy (TFM) procedures. However, these fluorescent markers may alter the mechanical properties of the matrix or can be taken up by the embedded cells, and therefore influence cellular behavior and fate. In addition, the currently developed methods for calculating cell-induced deformations are generally limited to relatively small deformations, with displacement magnitudes and strains typically of the order of a few microns and less than 10% respectively. Yet, large, complex deformation fields can be expected from cells exerting tractions in fibrillar biomaterials, like collagen. To circumvent these hurdles, we present a technique for the 3D full-field quantification of large cell-generated deformations in collagen, without the need of fiducial markers. We applied non-rigid, Free Form Deformation (FFD)-based image registration to compute full-field displacements induced by MRC-5 human lung fibroblasts in a collagen type I hydrogel by solely relying on second harmonic generation (SHG) from the collagen fibrils. By executing comparative experiments, we show that comparable displacement fields can be derived from both fibrils and fluorescent beads. SHG-based fibril imaging can circumvent all described disadvantages of using fiducial markers. This approach allows measuring 3D full-field deformations under large displacement (of the order of 10 μm) and strain regimes (up to 40%). As such, it holds great promise for the study of large cell-induced deformations as an inherent component of cell-biomaterial interactions and cell-mediated biomaterial remodeling.publisher: Elsevier articletitle: 3D full-field quantification of cell-induced large deformations in fibrillar biomaterials by combining non-rigid image registration with label-free second harmonic generation journaltitle: Biomaterials articlelink: http://dx.doi.org/10.1016/j.biomaterials.2017.05.015 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved.status: publishe

Biocompatible Label-Free Detection of Carbon Black Particles by Femtosecond Pulsed Laser Microscopy

Although adverse health effects of carbon black (CB) exposure are generally accepted, a direct, label-free approach for detecting CB particles in fluids and at the cellular level is still lacking. Here, we report nonincandescence related white-light (WL) generation by dry and suspended carbon black particles under illumination with femtosecond (fs) pulsed near-infrared light as a powerful tool for the detection of these carbonaceous materials. This observation is done for four different CB species with diameters ranging from 13 to 500 nm, suggesting this WL emission under fs near-infrared illumination is a general property of CB particles. As the emitted radiation spreads over the whole visible spectrum, detection is straightforward and flexible. The unique property of the described WL emission allows optical detection and unequivocal localization of CB particles in fluids and in cellular environments while simultaneously colocalizing different cellular components using various specific fluorophores as shown here using human lung fibroblasts. The experiments are performed on a typical multiphoton laser-scanning microscopy platform, widely available in research laboratories.status: publishe

Monitoring indoor exposure to combustion-derived particles using plants

Indoor plants can be used to monitor atmospheric particulates. Here, we report the label-free detection of combustion-derived particles (CDPs) on plants as a monitoring tool for indoor pollution. First, we measured the indoor CDP deposition on Atlantic ivy leaves (Hedera hibernica) using two-photon femtosecond microscopy. Subsequently, to prove its effectiveness for using it as a monitoring tool, ivy plants were placed near five different indoor sources. CDP particle area and number were used as output metrics. CDP values ranged between a median particle area of 0.45 × 102 to 1.35 × 104 μm2, and a median particle number of 0.10 × 102 to 1.42 × 10³ particles for the indoor sources: control (greenhouse) < milling machine < indoor smokers < wood stove < gas stove < laser printer. Our findings demonstrate that Atlantic ivy, combined with label-free detection, can be effectively used in indoor atmospheric monitoring studies.status: publishe

Biocompatible Label-Free Detection of Carbon Black Particles by Femtosecond Pulsed Laser Microscopy

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In vivo Toxicity Assessment of Silver Nanoparticles in Homeostatic versus Regenerating Planarians

Silver nanoparticles (AgNPs) belong to the most commercialized nanomaterials, used in both consumer products and medical applications. Despite its omnipresence, in-depth knowledge on the potential toxicity of nanosilver is still lacking, especially for developing organisms. Research on vertebrates is limited due to ethical concerns, and planarians are an ideal invertebrate model to study the effects of AgNPs on stem cells and developing tissues in vivo, as regeneration mimics development by triggering massive stem cell proliferation. Our results revealed a strong interference of AgNPs with tissue- and neuroregeneration which was related to an altered stem cell cycle. The presence of a PVP-coating significantly influenced toxicity outcomes, leading to elevated DNA-damage and decreased stem cell proliferation. Non-coated AgNPs had an inhibiting effect on stem cell and early progeny numbers. Overall, regenerating tissues were more sensitive to AgNP toxicity, and careful handling and appropriate decision making is needed in AgNP applications for healing and developing tissues. We emphasize on the importance of AgNP characterization, as we showed that changes in physicochemical properties influence toxicity.</p

Ambient black carbon particles reach the fetal side of human placenta

Particle transfer across the placenta has been suggested but to date, no direct evidence in real-life, human context exists. Here we report the presence of black carbon (BC) particles as part of combustion-derived particulate matter in human placentae using white-light generation under femtosecond pulsed illumination. BC is identified in all screened placentae, with an average (SD) particle count of 0.95 × 104 (0.66 × 104) and 2.09 × 104 (0.9 × 104) particles per mm3 for low and high exposed mothers, respectively. Furthermore, the placental BC load is positively associated with mothers' residential BC exposure during pregnancy (0.63-2.42 µg per m3). Our finding that BC particles accumulate on the fetal side of the placenta suggests that ambient particulates could be transported towards the fetus and represents a potential mechanism explaining the detrimental health effects of pollution from early life onwards.status: publishe