Newly demonstrated advanced biosensor imaging technologies utilize the unique electromagnetic capabilities of photonic metamaterials to enhance the interaction between light and biological matter. The resulting capabilities address gaps in existing technologies for biomolecular analysis that rely upon enzymatic and chemical amplification, costly instrumentation, and complex assay protocols. Through amplification of the excitation/extraction efficiency of light emitting tags, absorption efficiency of nanoparticle tags, and scattering efficiency of biological analytes, technology platforms have been demonstrated that are capable of ultrasensitive, digital-resolution, room temperature, isothermal, rapid, and highly quantitative biomolecular analysis.
Direct visualization and characterization of nanosized biological particles such as viruses, vesicles and protein aggregates are important for various applications in medicine. Specifically, exosomes (30-150 nm in diameter) gained huge interest due to their potential role as a biomarker in cancer diagnosis and prognosis, however direct detection of these particles is challenging due to their small size. Interferometric microscopy allows detection of these particles without using any labels. We show that visibility of nanoparticles can be enhanced in interferometric microscopy by utilizing defocused images. In this paper, with the proposed method Depth Scanning Correlation, we demonstrate label-free detection of individual exosomes isolated from breast cancer cell culture isolated by using Exosome Total Isolation Chip (ExoTIC). Proposed imaging system combined with an isolation tool, can be used in a wide range of applications, where label-free detection of single biological nanoparticles is needed.
A range of cellular, architectural, and physical cues in the tumor microenvironment influence the intrinsic and acquired resistance mechanisms that lead to treatment failure. Strategies that leverage photodynamic therapy (PDT), a photochemistry-based biophysical treatment modality, to regionally target and prime stubborn tumor populations may be essential to realizing durable improvements in cancer management while minimizing toxicity from traditional agents. Capturing these attributes in rationally-designed combinations has shown promise by synergistically reducing tumor area in 3D models, and durably controlling tumor burden in vivo. Among the areas that remain understudied is the influence of mechanical forces, such as hydrodynamic shear stress, on resistance, and the development of 3D tumor models and in vivo models that account for physical stress. To evaluate and optimize PDT regimens, and PDT-based combinations, designed to overcome resistance to conventional therapies due to physical stress, a multi-faceted approach is needed. Here the impact of hydrodynamic stress is evaluated in bioengineered 3D tumor models in the context of ovarian cancer. The potential value of using biologically inspired in vitro models to guide customized, rationally-designed PDT-based combination regimens will be presented.
Development of label-free, highly sensitive, miniaturized surface plasmon resonance sensors enables real-time quantification of biomolecule interactions at atomic-levels, desirable for medical diagnostics and which will allow rapid clinical decisions. However, multi-target diagnostic assays require skilled labor, expensive materials, lengthy manual steps, as well as complicated analysis steps. Here, we develop a microfluidic-integrated digital optical disc (DVD) grating as a metasurface, which is coated with titanium-silver-gold (Ti-Ag-Au, 10, 30, and 15nm) for real-time monitoring of biomolecular interactions and binding affinities. Device fabrication process consists of poly (methyl methacrylate) (PMMA) microfluidic channel assembly on nanoplasmonic DVD surface gratings via double side adhesive (DSA) layers. Compared with other nano- and micro-fabrication methods, DVD-based sensor fabrication is relatively simple, cost-effective, and enables large-scale fabrication with minimum efforts. The plasmonic microfluidic chip surface was illuminated with a broadband light source and the normal reflection signal was monitored using a customized optical-setup. Maximum bulk sensitivity (337 nm/RIU) was observed with 30 seconds of etching period and low glycerol concentration (5%, v/v). Red-shifts of peak-wavelength (~16 nm) upon glycerol concentrations were observed as a function of time (seconds). A 0.6 nm peak-wavelength shift was observed in the step of EDC/NHS coupling and continuous protein A/G and G binding resulted in 0.353 ± 0.211 nm and 0.667 ± 0.116 nm (n=3, p<0.05). The presented platform could be potentially applicable to detect and real-time monitor of various biotargets including bacteria, cells, viruses, and proteins.
Drug resistance to conventional therapies remains a major cause of treatment failure, tumor recurrence and dismal survival rates for patients with advanced stage cancers. Photodynamic therapy (PDT) provides an opportunity to exploit photochemically-triggered death mechanisms via targeting of sub-cellular, cellular and stromal compartments to overcome treatment resistance in unresponsive populations of stubborn disease. The informed design of mechanism-based combinations is emerging as increasingly important to targeting resistance and improving the efficacy of conventional treatments, while minimizing toxicity. PDT has been shown to synergize with conventional agents and to overcome the evasion pathways that cause resistance. Increasing evidence shows that PDT-based combinations cooperate mechanistically with, and improve the therapeutic index of, traditional chemotherapies. These and other findings emphasize the importance of including PDT as part of comprehensive treatment plans for cancer, particularly in complex disease sites. Identifying effective combinations requires a multi-faceted approach that includes the development of bioengineered cancer models and corresponding image analysis tools. The presentation will focus on the molecular and phenotypic basis of verteporfin PDT-based enhancement of chemotherapeutic efficacy and predictability in complex 3D models and in vivo models, with a particular emphasis on ovarian and pancreatic cancer.
Previous studies have demonstrated that flow-induced shear stress induces a motile and aggressive tumor phenotype in a microfluidic model of 3D ovarian cancer. However, the magnitude and distribution of the hydrodynamic forces that influence this biological modulation on the 3D cancer nodules are not known. We have developed a series of numerical and experimental tools to identify these forces within a 3D microchannel. In this work, we used particle image velocimetry (PIV) to find the velocity profile using fluorescent micro-spheres as surrogates and nano-particles as tracers, from which hydrodynamic forces can be derived. The fluid velocity is obtained by imaging the trajectory of a range of florescence nano-particles (500–800 μm) via confocal microscopy. Imaging was done at different horizontal planes and with a 50 μm bead as the surrogate. For an inlet current rate of 2 μl/s, the maximum velocity at the center of the channel was 51 μm/s. The velocity profile around the sphere was symmetric which is expected since the flow is dominated by viscous forces as opposed to inertial forces. The confocal PIV was successfully employed in finding the velocity profile in a microchannel with a nodule surrogate; therefore, it seems feasible to use PIV to investigate the hydrodynamic forces around 3D biological models.
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