Direct Measurement of a Biomarker's Native Optimal Frequency with Physical Adsorption Based Immobilization.

The optimal frequency (OF) of a biomarker in electrochemical impedance spectroscopy (EIS) is the frequency at which the EIS response best reflects the binding of the biomarker to its molecular recognition element. Commonly, biosensors rely on complicated immobilization chemistry to attach biological molecules to the sensor surface, making the direct study of a biomarker's native OF a challenge. Physical adsorption presents a simple immobilization strategy to study the native biomarker's OF, but its utility is often discouraged due to a loss in biological activity. To directly study a biomarker's native OF and investigate the potential of OF to overcome the limitations of physical adsorption, a combination of EIS and glutaraldehyde-mediated physical adsorption was explored. The experimental sensing platform was prepared by immobilizing either anti-lactoferrin (Lfn) IgG or anti-immunoglobulin E (IgE) onto screen printed carbon electrodes. After characterizing the native OFs of both biomarkers, investigation of the platform's specificity, stability, and performance in complex medium was found to be sufficient. Finally, a paper-based tear sampling component was integrated to transform the testing platform into a prototypical point-of-care dry eye diagnostic. The investigation of native OFs revealed a correlation between the native OFs (57.44 and 371.1 Hz for Lfn and IgE, respectively) and the molecular weight of the antibody-antigen complex. Impedance responses at the native OFs have enabled detection limits of 0.05 mg/mL and 40 ng/mL for Lfn and IgE, respectively, covering the clinically relevant ranges. The native OFs were found to be robust across various testing mediums and conditions.

Flow-perfusion bioreactor system for engineered breast cancer surrogates to be used in preclinical testing.

There is a need for preclinical testing systems that predict the efficacy, safety and pharmacokinetics of cancer therapies better than existing in vitro and in vivo animal models. An approach to the development of predictive in vitro systems is to more closely recapitulate the cellular and spatial complexity of human cancers. One limitation of using current in vitro systems to model cancers is the lack of an appropriately large volume to accommodate the development of this complexity over time. To address this limitation, we have designed and constructed a novel flow-perfusion bioreactor system that can support large-volume, engineered tissue comprised of multicellular cancer surrogates by modifying current microfluidic devices. Key features of this technology are a three-dimensional (3D) volume (1.2 cm3 ) that has greater tissue thickness than is utilized in existing microfluidic systems and the ability to perfuse the volume, enabling the development of realistic tumour geometry. The constructs were fabricated by infiltrating porous carbon foams with an extracellular matrix (ECM) hydrogel and engineering through-microchannels. The carbon foam structurally supported the hydrogel and microchannel patency for up to 161 h. The ECM hydrogel was shown to adhere to the carbon foam and polydimethylsiloxane flow chamber, which housed the hydrogel-foam construct, when surfaces were coated with glutaraldehyde (carbon foam) and nitric acid (polydimethylsiloxane). Additionally, the viability of breast cancer cells and fibroblasts was higher in the presence of perfused microchannels in comparison to similar preparations without microchannels or perfusion. Therefore, the flow-perfusion bioreactor system supports cell viability in volume and stromal contexts that are physiologically-relevant. Copyright © 2015 John Wiley & Sons, Ltd.

Development of gellan gum containing formulations for transdermal drug delivery: Component evaluation and controlled drug release using temperature responsive nanogels.

Enhancing skin permeation is important for development of new transdermal drug delivery formulations. This is particularly relevant for non-steroidal anti-inflammatory drugs (NSAIDs). To address this, semisolid gel and solid hydrogel film formulations containing gellan gum as a gelling agent were developed and the effects of penetration enhancers (dimethyl sulfoxide, isopropyl alcohol and propylene glycol) on transport of the NSAID diclofenac sodium was quantified. A transwell diffusion system was used to accelerate formulation development. After 4h, diclofenac flux from a superior formulation of the semisolid gel or the solid hydrogel film was 130±11µg/cm(2)h and 108±7µg/cm(2)h, respectively, and significantly greater than that measured for a currently available diclofenac sodium topical gel (30±4µg/cm(2)h, p<0.05) or solution formulation (44±6µg/cm(2)h, p<0.05) under identical conditions. Over 24h diclofenac transport from the solid hydrogel film was greater than that measured for any new or commercial diclofenac formulation. Entrapment of temperature-responsive nanogels within the solid hydrogel film provides temperature-activated prolonged release of diclofenac. Diclofenac transport was minimal at 22°C, when diclofenac is entrapped within temperature-responsive nanogels incorporated into the solid hydrogel film, but increased 6-fold when the temperature was increased to skin surface temperature of 32°C. These results demonstrate the feasibility of the semisolid gel and solid hydrogel film formulations that can include thermo-responsive nanogels for development of transdermal drug formulations with adjustable drug transport kinetics.

PET imaging a MPTP-induced mouse model of Parkinson's disease using the fluoropropyl-dihydrotetrabenazine analog [18F]-DTBZ (AV-133).

Parkinson's disease (PD) is characterized by the loss of dopamine-producing neurons in the nigrostriatal system. Numerous researchers in the past have attempted to track the progression of dopaminergic depletion in PD. We applied a quantitative non-invasive PET imaging technique to follow this degeneration process in an MPTP-induced mouse model of PD. The VMAT2 ligand (18)F-DTBZ (AV-133) was used as a radioactive tracer in our imaging experiments to monitor the changes of the dopaminergic system. Intraperitoneal administrations of MPTP (a neurotoxin) were delivered to mice at regular intervals to induce lesions consistent with PD. Our results indicate a significant decline in the levels of striatal dopamine and its metabolites (DOPAC and HVA) following MPTP treatment as determined by HPLC method. Images obtained by positron emission tomography revealed uptake of (18)F-DTBZ analog in the mouse striatum. However, reduction in radioligand binding was evident in the striatum of MPTP lesioned animals as compared with the control group. Immunohistochemical analysis further confirmed PET imaging results and indicated the progressive loss of dopaminergic neurons in treated animals compared with the control counterparts. In conclusion, our findings suggest that MPTP induced PD in mouse model is appropriate to follow the degeneration of dopaminergic system and that (18)F-DTBZ analog is a potentially sensitive radiotracer that can used to diagnose changes associated with PD by PET imaging modality.