Lowfrequency Sonophoresis

Low-frequency sonophoresis has been a topic of extensive research only in the last 10 years. Tachibana et al. 60-62 reported that application of low-frequency ultrasound (48 kHz) enhanced transdermal transport of lidocaine and insulin across hairless rat skin in vivo. They found that the blood glucose level of a hairless rat immersed in a beaker filled with insulin solution (20 U ml) and placed in an ultrasound bath (48 kHz, 5000 Pa) decreased by 50 in 240 minutes 62 . They also showed that...

Matrix Materials Inside The Biocapsule

Oxygen is known to be a critical factor that influences insulin secretion by islets. The diffusional limitations imposed by a biocapsule construct can potentially make it a hy-poxic environment for the cells. In the attempt to partially overcome this constraint, cells were seeded in various extracellular matrix materials within the biocapsule. Their behavior was compared with free cells, which form aggregates. We showed that the addition of a matrix, particularly alginate or collagen, within...

Biocompatibility Of Nanoporous Membranes And Biocapsular Environment

Early studies showed that silicon microdevices were biocompatible in vitro and in vivo 55 . For these microimplants, there appeared to be no changes in the mechanical properties of the implants and no corrosion was observed. The filtration channels appeared clear and free from any obstructions. No gross abnormalities of color or consistency were observed in the tissue surrounding the implant. No necrosis, calcification, tumorgenesis, or infection was observed at any of the implant sites,...

Microscale Phenomena

The ability of microtechnologies to create structures and patterns on micron and smaller length scales provides a powerful means to manipulate cells and their microenvironments. Miniaturized bioanalytical systems can handle small reagent volumes with shorter reaction times and control biochemical composition and topology of substrates at a cellu-lar subcellular level. Since length scale is a fundamental quantity that dictates the type of forces governing physical phenomena, however, successful...

Potential Uses Of Nanotechnology In Pulmonary Diseases

It is truly impossible for us to conceive or predict how all of the achievements in science may eventually channel into advances in medicine. It is, though, a useful pleasure to make the attempt. We can anticipate that particular tasks will continue to need to be accomplished. We will frame this discussion using those basic medical tasks. These immutable tasks are 1) diagnosis and 2) therapeutics or management of disease. Therapeutics may be divided further into the administration of...

Info

The figure demonstrates the effect of introducing heterotypic cell-cell contacts on hepatocyte differentiation in vitro. Red color indicates the synthesis of albumin, a marker for hepatocyte differentiation. A and B respectively are micropatterned hepatocytes cultured in isolation or in co-culture with fibroblasts. C and D show cultures under the same conditions after six days. Note the greater loss of albumin from isolated hepatocytes C compared to co-cultures D. E shows a...

Siliconbased Porous Materials

A recent approach in the development of controllable reservoir-based drug delivery systems involves the use of more rigid inorganic porous solids as substrate materials for the preparation of functionalized organic inorganic nanostructured drug carriers 11 . In particular, nanostructured materials based on Si are very promising platforms for pharmaceutical applications. Porous silica 12,13 and porous Si 14 are good examples of this class. Their more complex architectural and chemical structures...

History Of Neurosurgery

The art of neurosurgery dates back to the Neolithic time (late stone age) with evidence of brain surgery found in the unearthed remains from this era 4,15,21,27, 32 . Many ancient FIGURE 6.1. Schematic illustration of the central nervous system. Neurosurgery refers to the operative and subsequent non-operative care of disorders that affect the central, peripheral and autonomic nervous system as well as the management of pain. Neurosurgeons also treat disorders of the vascular and skeletal...

Introduction

The Science of Miniaturization (MEMS and BioMEMS) Micro-Electro-Mechanical Systems technology, commonly known with the acronym MEMS, refers to the fabrication of devices with dimensions on the micrometer scale. For comparison, a human hair is about 80 im in diameter. The most essential elements of MEMS consist of miniaturized, highly precise, and repeatable structures that can be stationary or moving. These structures are created via fabrication processes and equipment developed for the...

Biocompatibility Of Nanoporous Implants

The material-tissue interaction that results from the device implantation is one of the major obstacles in developing viable, long-term implantable drug delivery systems. Membrane biofouling is a process that starts immediately upon contact of a device with the body when cells, proteins and other biological components adhere to the surface, and in some cases, impregnate the pores of the material 72 . Not only does biofouling of the membrane impede drug diffusion (i.e. release) from the implant...

Porous Silicon

The attraction of placing active electronic circuit components into in-vivo drug delivery materials led to the exploration of elemental silicon as a biomaterial. In particular a porous form of Si produced by an electrochemical corrosion reaction has been of interest. Since the pioneering work of Canham and others in the late 90's demonstrating the biocompatibility and biodegradability of porous Si in vitro and in vivo 25-35 , this material has been under intensive investigation for controlled...

Surface Chemistry

Techniques used to associate proteins and polymers include covalent linkage and passive adsorption. Although covalent linkage is often more stable than simple adsorption, it is possible that the stability and function of the conjugates may be impaired. Covalent linkage requires the presence of functional groups on the surface of the substrate. Protein-carrier conjugates have been prepared through activation of hydroxyl, carboxyl, and amino groups FIGURE 14.7. Scanning electron micrograph of a...

Huvec Cell Culture

Schematic of a potential multi-phenotypic biosensor. Six different cell lines are isolated in hydrogel arrays in six different microfluidic channels. Several cellular assays can be performed using one array. Multi-phenotypic arrays offer the advantage of providing more information about cellular responses than existing arrays and lend themselves to miniaturization, which could lead to high degrees of multiplexing. Multi-phenotypic cell based biosensors show promise in the area of...