Biomedical subjects

Mario Cabodi

Publications and source records attributed to Mario Cabodi.

4 recordsLinked to original sources

PubMed2007

An active wound dressing for controlled convective mass transfer with the wound bed.

Conventional wound dressings-gauze, plastic films, foams, and gels-do not allow for spatial and temporal control of the soluble chemistry within the wound bed, and are thus limited to a passive role in wound healing. Here, we present an active wound dressing (AWD) designed to control convective mass transfer with the wound bed; this mass transfer provides a means to tailor and monitor the chemical state of a wound and, potentially, to aid the healing process. We form this AWD as a bilayer of porous poly(hydroxyethyl methacrylate) (pHEMA) and silicone; the pHEMA acts as the interface with the wound bed, and a layer of silicone provides a vapor barrier and a support for connecting to external reservoirs and pumps. We measure the convective permeability of the pHEMA sponge, and use this value to design a device with a spatially uniform flow profile. We quantify the global coefficient of mass transfer of the AWD on a dissolvable synthetic surface, and compare it to existing theories of mass transfer in porous media. We also operate the AWD on model wound beds made of calcium alginate gel to demonstrate extraction and delivery of low molecular weight solutes and a model protein. Using this system, we demonstrate both uniform mass transfer over the entire wound bed and patterned mass transfer in three spatially distinct regions. Finally, we discuss opportunities and challenges for the clinical application of this design of an AWD.

Alginates↗

PubMed2005

A microfluidic biomaterial.

We report on the incorporation of microfluidic structure within a high-water-content hydrogel [4% (w/v) calcium alginate]. We used the microfluidic network to control the chemical environment within the hydrogel and demonstrated higher rates of delivery and extraction of solutes than was achievable by diffusion alone.

Alginates↗

PubMed2002

Entropic recoil separation of long DNA molecules.

A novel technique that can rapidly separate long-strand polymers according to length is presented. The separation mechanism is mediated by a confinement-induced entropic force at the abrupt interface between regions of vastly different configuration entropy. To demonstrate this technique, DNA molecules were partially inserted into a dense array of nanopillars (an entropically unfavorable region) using a pulsed electric field and allowed to relax to their natural state by removal of the field. Molecules of dissimilar lengths (T2 and T7 coliphage DNA) were inserted into this region in such a way that shorter molecules were fully inserted in this region, while longer molecules remained partially across the interface. The longer T2 molecules were observed to recoil entirely out of the pillar array, leaving the shorter T7 molecules inserted, and effecting separation of the two species in a single step. To show how this method can be used for separation of unknown samples, the inserting electric field was pulsed for progressively longer times, allowing passage of progressively longer molecules and producing the equivalent of a conventional electropherogram. The effects limiting resolution in this device are discussed, and the expected separating power of a multistage device is reported. The extracted resolution and running separation time compare favorably with current conventional separation techniques.

Algorithms↗

PubMed2002

Continuous separation of biomolecules by the laterally asymmetric diffusion array with out-of-plane sample injection.

The laterally asymmetric diffusion array, a biomolecule sorting device, was used to continuously separate a mixture of T2 and T7 coliphage DNA molecules into its constituents. A two-dimensional array of obstacles (in the presence of an average flow v) can be used to rectify the Brownian motion of particles (in this case DNA molecules) so that they diffuse preferentially in one direction, and perpendicular to the direction of the applied field (in this case an electric field). This type of device had not yet been used for actual fractionation of biomolecules, due to difficulties in injection of the sample. Here we show that with a new injection strategy a well-defined, narrow and continuous stream of molecules can be injected into the separation channel, thus enabling this separation technique to be used in a working device. We expect this type of device could now be employed for separation of a variety of different biomolecules, ranging from long dsDNA to small proteins.

Bacteriophage T4↗