Multiscale benchmarking of drug delivery vectors

Cross-system comparisons of drug delivery vectors are essential to ensure optimal design. An in-vitro experimental protocol is presented that separates the role of the delivery vector from that of its cargo in determining the cell response, thus allowing quantitative comparison of different systems. The technique is validated through benchmarking of the dose–response of human fibroblast cells exposed to the cationic molecule, polyethylene imine (PEI); delivered as a free molecule and as a cargo on the surface of CdSe nanoparticles and Silica microparticles. The exposure metrics are converted to a delivered dose with the transport properties of the different scale systems characterized by a delivery time, τ. The benchmarking highlights an agglomeration of the free PEI molecules into micron sized clusters and identifies the metric determining cell death as the total number of PEI molecules presented to cells, determined by the delivery vector dose and the surface density of the cargo

Analysis of the Influence of Cell Heterogeneity on Nanoparticle Dose Response

Understanding the effect of variability in the interaction of individual cells with nanoparticles on the overall response of the cell population to a nanoagent is a fundamental challenge in bionanotechnology. Here, we show that the technique of time-resolved, high-throughput microscopy can be used in this endeavor. Mass measurement with single-cell resolution provides statistically robust assessments of cell heterogeneity, while the addition of a temporal element allows assessment of separate processes leading to deconvolution of the effects of particle supply and biological response. We provide a specific demonstration of the approach, in vitro, through time-resolved measurement of fibroblast cell (HFF-1) death caused by exposure to cationic nanoparticles. The results show that heterogeneity in cell area is the major source of variability with area-dependent nanoparticle capture rates determining the time of cell death and hence the form of the exposure–response characteristic. Moreover, due to the particulate nature of the nanoparticle suspension, there is a reduction in the particle concentration over the course of the experiment, eventually causing saturation in the level of measured biological outcome. A generalized mathematical description of the system is proposed, based on a simple model of particle depletion from a finite supply reservoir. This captures the essential aspects of the nanoparticle–cell interaction dynamics and accurately predicts the population exposure–response curves from individual cell heterogeneity distributions

Optical Pick and Place Machine

The current market does not contain a low-cost machine capable of building optical surface mounted devices (SMDs). This project attempts to design a machine capable of handling optical parts which are highly sensitive components that rely on accurate placement. The machine will be a mixture of existing technology and specifically designed parts. This machine was designed around a Computer Numeric Control (CNC) machine frame (OpenBuilds). A controller conducts all actions performed by the machine. These actions include motion along x-, y-, and z-axes along with rotational motion. There is also a dual-camera subsystem which helps the user to determine ideal optical part placement. The machine is reprogrammable by using opensource software. Overall, it will provide optical SMD design capability to a larger population by decreasing the cost of such a machine

Iron-oxide nanoparticles as a contrast agent in thermoacoustic tomography

We investigate the feasibility of using iron oxide nanoparticles as a contrast agent for radiofrequency (RF) induced thermoacoustic tomography. Aqueous colloids of iron oxide (Fe3O4) nanoparticles have been synthesized and characterized. The synthesis method yielded citrate-stabilized, spherical particles with a diameter of approximately 10 nm. The complex permittivity of the colloids was measured with a coaxial probe and vector network analyzer, and the microwave absorption properties were calculated by using a relationship between the complex permittivity and absorption coefficients. Using our pulsed thermoacoustic imaging system at 3 GHz, the time-resolved thermoacoustic responses of those colloids were measured and compared to that of deionized water. Finally, two-dimensional thermoacoustic images were acquired from iron oxide colloids in a tissue phantom. The iron oxide colloids produced an enhancement in RF absorption of up to three times that of deionized water at 3 GHz. The enhancement increased rapidly with decreasing frequency of the RF excitation source. A corresponding increase in time-resolved thermoacoustic signal of more than two times was demonstrated. Our results indicate that iron oxide nanoparticles have the potential to produce enhanced thermoacoustic signals and to provide molecular imaging with functionalized contrast agents for thermoacoustic tomography

Optical Pick and Place Machine

The current market does not contain a low-cost machine capable of building optical surface mounted devices (SMDs). This project attempts to design a machine capable of handling optical parts which are highly sensitive components that rely on accurate placement. The machine will be a mixture of existing technology and specifically designed parts. This machine was designed around a Computer Numeric Control (CNC) machine frame (OpenBuilds). A controller conducts all actions performed by the machine. These actions include motion along x-, y-, and z-axes along with rotational motion. There is also a dual-camera subsystem which helps the user to determine ideal optical part placement. The machine is reprogrammable by using opensource software. Overall, it will provide optical SMD design capability to a larger population by decreasing the cost of such a machine

Encapsulation of FITC to monitor extracellular pH: a step towards the development of red blood cells as circulating blood analyte biosensors

A need exists for a long-term, minimally-invasive system to monitor blood analytes. For certain analytes, such as glucose in the case of diabetics, a continuous system would help reduce complications. Current methods suffer significant drawbacks, such as low patient compliance for the finger stick test or short lifetime (i.e., 3–7 days) and required calibrations for continuous glucose monitors. Red blood cells (RBCs) are potential biocompatible carriers of sensing assays for long-term monitoring. We demonstrate that RBCs can be loaded with an analyte-sensitive fluorescent dye. In the current study, FITC, a pH-sensitive fluorescent dye, is encapsulated within resealed red cell ghosts. Intracellular FITC reports on extracellular pH: fluorescence intensity increases as extracellular pH increases because the RBC rapidly equilibrates to the pH of the external environment through the chloride-bicarbonate exchanger. The resealed ghost sensors exhibit an excellent ability to reversibly track pH over the physiological pH range with a resolution down to 0.014 pH unit. Dye loading efficiency varies from 30% to 80%. Although complete loading is ideal, it is not necessary, as the fluorescence signal is an integration of all resealed ghosts within the excitation volume. The resealed ghosts could serve as a long-term (>1 to 2 months), continuous, circulating biosensor for the management of diseases, such as diabetes