Biological Devices Research Articles

Nanoelectromechanics of Inorganic and Biological Systems: From Structural Imaging to Local Functionalities

Abstract Coupling between electrical and mechanical phenomena is extremely common in inorganic materials, and nearly ubiquitous in biological systems, underpinning phenomena and devices ranging from SONAR to cardiac activity and hearing. This paper briefly summarizes the Scanning Probe Microscopy (SPM) approach, referred to as Piezoresponse Force Microscopy (PFM), for probing electromechanical coupling on the nanometer scales, and delineates some existing and emerging applications to probe local structure and functionality in inorganic ferroelectrics, calcified and connective tissues, and complex biosystems based on electromechanical detection.

Long-term performance of the Hancock bioprosthetic conduit for aortic root replacement

Objectives: The aim of this study was to examine the long-term clinical results and prosthesis durability after aortic root replacement with the bioprosthetic porcine Hancock conduit. Methods: From 1975 to 2004, 81 patients (mean age 58.1 years, range 14 to 82) underwent aortic root replacement with the Hancock conduit for aortic dissection (n=22, 27.2%), ascending aortic aneurysm (n=57, 70.4%), or ascending aortic calcification (n=2, 2.4%). 24 (29.6%) of the patients underwent emergency operation, 12 (14.8%) had marfan syndrome, 8 (9.9%) had previous cardiac surgery, and concomitant procedures were performed in 26 (32.1%). Follow-up was 97.5% complete with a cumulative follow-up of 403.1 patient years. Actuarial event-free rates are given as mean±standard error. Valve related complications were classified according to the guidelines for reporting morbidity and mortality after cardiac valvular operations. Results: There were 7(8.6%) operative and 4 (4.94%) perioperative deaths, being related to poor preoperative clinical conditions. Actuarial survival rates at 5/10/15 years, excluding operative deaths, were 77.1%±5.3%, 53.8%±7.5% and 36.9%±8.2%. The freedom from aortic valve reoperation at 5/10/15 years was 98.4%±1.6%, 64.3%±10.2% and 36.2%±12.1%. The actuarial freedom at 5/10/15 years from structural valve deterioration was 88.1%±4.7%, 49.9%±9.6% and 10.5%±8.9%, from non structural valve dysfunction 100% for all, from thrombembolic events 87.4%±4.6%, 75.1%±9.5% and 75.1%±9.5% and from major bleeding events 90.2%±3.9%, 75.4%±8.1% and 44.7%±19.6%. Conclusions: In a cohort of high risk patients we demonstrated good mid-term clinical outcome after aortic root replacement with the bioprosthetic Hancock conduit. However, long-term durability of the prosthesis seems less than expected for a biological device.

Controlled Electrophoretic Deposition of Uniquely Nanostructured Star Polymer Films

The controlled electrophoretic deposition of polystyrene/divinylbenzene (PS/DVB) star polymer films from a colloidal suspension is reported. Liquid suspensions, containing the PS/DVB star polymer, were prepared by injecting a dichloromethane (DCM) solution of the star polymer into a stratified liquid combination of hexane and DCM. A variety of hexane/DCM volume ratios were examined to identify the optimal solution conditions for electrophoretic deposition; thin films were produced from both unmixed and well-mixed hexane/DCM suspensions. Unmixed suspensions yielded spatially separated thin films, deposited in a controlled fashion, that were dependent on the polarity of the corresponding electrode. Films on the positive electrode differed in thickness, microstructure, and appearance from those formed on the negative electrode. In contrast, films produced from well-mixed hexane/DCM suspensions deposited uniformly across only the negative electrode. Atomic force microscopy studies revealed nanostructured surface morphologies that were unique to each of these films. Additionally, these microscopy studies shed light on the possible conformations of star polymers adsorbed on a surface. By controlling the composition and the mixing state of the solution and by controlling the bias of electrodes, we achieved controlled deposition of star polymer films with a specific nanostructure. These nanostructured films may have broad use in optical and biological device applications.

Computational design of digital and memory biological devices

The use of combinatorial optimization techniques with computational design allows the development of automated methods to design biological systems. Automatic design integrates design principles in an unsupervised algorithm to sample a larger region of the biological network space, at the topology and parameter levels. The design of novel synthetic transcriptional networks with targeted behaviors will be key to understand the design principles underlying biological networks. In this work, we evolve transcriptional networks towards a targeted dynamics, by using a library of promoters and coding sequences, to design a complex biological memory device. The designed sequential transcription network implements a JK-Latch, which is fully predictable and richer than other memory devices. Furthermore, we present designs of transcriptional devices behaving as logic gates, and we show how to create digital behavior from analog promoters. Our procedure allows us to propose a scenario for the evolution of multi-functional genetic networks. In addition, we discuss the decomposability of regulatory networks in terms of genetic modules to develop a given cellular function. Summary. We show how to use an automated procedure to design logic and sequential transcription circuits. This methodology will allow advancing the rational design of biological devices to more complex systems, and we propose the first design of a biological JK-latch memory device.Electronic supplementary materialThe online version of this article (doi:10.1007/s11693-008-9017-0) contains supplementary material, which is available to authorized users.

Models for synthetic biology

Synthetic biological engineering is emerging from biology as a distinct discipline based on quantification. The technologies propelling synthetic biology are not new, nor is the concept of designing novel biological molecules. What is new is the emphasis on system behavior.The objective is the design and construction of new biological devices and systems to deliver useful applications. Numerous synthetic gene circuits have been created in the past decade, including bistable switches, oscillators, and logic gates, and possible applications abound, including biofuels, detectors for biochemical and chemical weapons, disease diagnosis, and gene therapies.More than fifty years after the discovery of the molecular structure of DNA, molecular biology is mature enough for real quantification that is useful for biological engineering applications, similar to the revolution in modeling in chemistry in the 1950s. With the excitement that synthetic biology is generating, the engineering and biological science communities appear remarkably willing to cross disciplinary boundaries toward a common goal.

Recent advances in application of acoustic, acousto‐optic and photoacoustic methods in biology and medicine

Abstract Various types of acoustic wave devices based on surface acoustic, acousto‐optic and photoacoustic effects are increasingly used for many biomedical applications. This paper reviews the basic physical phenomena of the acoustic wave propagation and photoacoustic and acousto‐optic interactions, which determine their sensing capabilities, and discusses recent applications of these devices in biology and medicine. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Engineering of Artificial Plant Cytochrome P450 Enzymes for Synthesis of Isoflavones by Escherichia coli

Engineered microbes are becoming increasingly important as recombinant production platforms. However, the nonfunctionality of membrane-bound cytochrome P450 enzymes precludes the use of industrially relevant prokaryotes such as Escherichia coli for high-level in vivo synthesis of many functional plant-derived compounds. We describe the design of a series of artificial isoflavone synthases that allowed the robust production of plant estrogen pharmaceuticals by E. coli. Through this methodology, a plant P450 construct was assembled to mimic the architecture of a self-sufficient bacterial P450 and contained tailor-made membrane recognition signals. The specific in vivo production catalyzed by one identified chimera was up to 20-fold higher than that achieved by the native enzyme expressed in a eukaryotic host and up to 10-fold higher than production by plants. This novel biological device is a strategy for the utilization of laboratory bacteria to robustly manufacture high-value plant P450 products.

Three-Dimensional Si/Ge Quantum Dot Crystals

Modern nanotechnology offers routes to create new artificial materials, widening the functionality of devices in physics, chemistry, and biology. Templated self-organization has been recognized as a possible route to achieve exact positioning of quantum dots to create quantum dot arrays, molecules, and crystals. Here we employ extreme ultraviolet interference lithography (EUV-IL) at a wavelength of lambda = 13.5 nm for fast, large-area exposure of templates with perfect periodicity. Si(001) substrates have been patterned with two-dimensional hole arrays using EUV-IL and reactive ion etching. On these substrates, three-dimensionally ordered SiGe quantum dot crystals with the so far smallest quantum dot sizes and periods both in lateral and vertical directions have been grown by molecular beam epitaxy. X-ray diffractometry from a sample volume corresponding to about 3.6 x 10(7) dots and atomic force microscopy (AFM) reveal an up to now unmatched structural perfection of the quantum dot crystal and a narrow quantum dot size distribution. Intense interband photoluminescence has been observed up to room temperature, indicating a low defect density in the three-dimensional (3D) SiGe quantum dot crystals. Using the Ge concentration and dot shapes determined by X-ray and AFM measurements as input parameters for 3D band structure calculations, an excellent quantitative agreement between measured and calculated PL energies is obtained. The calculations show that the band structure of the 3D ordered quantum dot crystal is significantly modified by the artificial periodicity. A calculation of the variation of the eigenenergies based on the statistical variation in the dot dimensions as determined experimentally (+/-10% in linear dimensions) shows that the calculated electronic coupling between neighboring dots is not destroyed due to the quantum dot size variations. Thus, not only from a structural point of view but also with respect to the band structure, the 3D ordered quantum dots can be regarded as artificial crystal.

Development of a Biological Ventricular Assist Device

Engineered heart tissue (EHT) can be generated from cardiomyocytes and extracellular matrix proteins and used to repair local heart muscle defects in vivo. Here, we hypothesized that pouch-like heart muscle constructs can be generated by using a novel EHT-casting technology and applied as heart-embracing cardiac grafts in vivo. Pouch-like EHTs (inner/outer diameter: 10/12 mm) can be generated mainly from neonatal rat heart cells, collagen type I, and serum containing culture medium. They contain a dense network of connexin 43 interconnected cardiomyocytes and an endo-/epicardial surface lining composed of prolylhydroxylase positive cells. Pouch-like EHTs beat spontaneously and show contractile properties of native heart muscle including positive inotropic responses to calcium and isoprenaline. First implantation studies indicate that pouch-like EHTs can be slipped over uninjured adult rat hearts to completely cover the left and right ventricles. Fourteen days after implantation, EHT-grafts stably covered the epicardial surface of the respective hearts. Engrafted EHTs were composed of matrix and differentiated cardiac muscle as well as newly formed vessels which were partly donor-derived. Pouch-like EHTs can be generated with structural and functional properties of native myocardium. Implantation studies demonstrated their applicability as cardiac muscle grafts, setting the stage for an evaluation of EHT-pouches as biological ventricular assist devices in vivo.

Self-formation of sub-60-nm half-pitch gratings with large areas through fracturing

Periodic micro- and nanostructures (gratings) have many significant applications in electronic, optical, magnetic, chemical and biological devices and materials. Traditional methods for fabricating gratings by writing with electrons, ions or a mechanical tip are limited to very small areas and suffer from extremely low throughput. Interference lithography can achieve relatively large fabrication areas, but has a low yield for small-period gratings. Photolithography, nanoimprint lithography, soft lithography and lithographically induced self-construction all require a prefabricated mask, and although electrohydrodynamic instabilities can self-produce periodic dots without a mask, gratings remain challenging. Here, we report a new low-cost maskless method to self-generate nano- and microgratings from an initially featureless polymer thin film sandwiched between two relatively rigid flat plates. By simply prising apart the plates, the film fractures into two complementary sets of nonsymmetrical gratings, one on each plate, of the same period. The grating period is always four times the thickness of the glassy film, regardless of its molecular weight and chemical composition. Periods from 120 nm to 200 microm have been demonstrated across areas as large as two square centimetres.

Growth of Carbon, Boron Nitride and ZnO Nanotubes for Biosensors

Nanotubes have significant portions of their atoms located at the surfaces and represent the future of biological devices. With such small dimensions, sensitivities and applications previously impossible are being made real. Not all nanomaterials are currently at the same level of proficiency, however. Carbon nanotubes are a mature, easily grown and controlled nanostructure, but boron nitride and zinc oxide are still coming into their own. Yet progress in all three species of nanotubes is making applications easier than before.

Method for determining the optimum time for preventative substitution of replaceable components of ecological and biological technology

A theoretically substantiated method is proposed for determining the period of performing preventative maintenance work connected with replacing failed assemblies (units) of biological protection devices. The calculation method is illustrated by a specific example of its application in practice and it makes it possible to prolong the duration of safe operation of devices and correspondingly to provide their operational reliability.

Awareness-level information for veterinarians on weapons of mass destruction and preservation of evidence

JAVMA, Vol 230, No. 12, June 15, 2007 W of mass destruction may be defined as chemical, biological, radiologic, nuclear, explosive, or incendiary devices intended to cause widespread injury or death. Injuries and illnesses resulting from weapons of mass destruction may be overt, subclinical, or delayed. Because veterinarians may find themselves responding to emergency incidents, they should be aware of the agents that may cause mass casualties. Importantly, if such agents have been used intentionally, then the incident is a crime scene, and responders should be aware of the need to secure the scene and preserve evidence. If the incident was intended to intimidate or coerce for social or political reasons, then it is classified as an act of terrorism, and federal regulations and authorities have jurisdiction. Specifically, animal enterprise terrorism has been defined as a crime that causes physical disruption to the functioning of an animal enterprise or economic damages exceeding $10,000 to that enterprise. There is little published information on the effects of most weapons of mass destruction in animals, although some information has been published on possible dangers for search-and-rescue dogs working in postdisaster environments. Nevertheless, veterinarians may obtain some useful comparative information from published reports of the effects of weapons of mass destruction on humans and their treatment. Because of the potential for veterinarians to be involved in the response to an incident involving weapons of mass destruction, they should have at least some awarenesslevel information of the various agents that might be used. Similarly, although law enforcement personnel are responsible for securing crime scenes, gathering and preserving evidence, and maintaining a documented chain of custody for such evidence, veterinarians should have at least some rudimentary knowledge of the principles and practices of evidence preservation because they may be involved in rendering aid at the site of a disaster or treating victims at the site or elsewhere.

The iGEM competition: building with biology

Can simple biological systems be built from standard, interchangeable parts and operated in living cells? Or is biology simply too complicated to be engineered in this way? The international Genetically Engineered Machine Competition (iGEM) is an open design challenge for student teams that addresses this difficult question. Using a library of standardised parts known as BioBricks, groups of undergraduates from around the world spend their summer designing and assembling biological devices, to build genetic machines.

Fabrication of microchannel containing nanopillar arrays using micromachined AAO (anodic aluminum oxide) mold

In this paper, we present a novel low cost fabrication method of a microchannel containing nanopillar arrays based on the soft lithographical replication of PDMS (polydimethylsiloxane) using a micromachined AAO (anodic aluminum oxide) master mold without any photolithographic processes. The micromachined AAO master mold was fabricated by combining the two-step anodization, micro-end-milling and the subsequent electropolishing processes, thereby having a nanoporous alumina layer on top of the micro-end-milled microchannel positive relief. Large numbers of the same microchannel with nanopillar arrays were finally realized by the PDMS replica molding from the micromachined AAO mold. The microchannel with nanopillar arrays fabricated in this study could be applied to various integrated biological, chemical or optical devices.

Characterization of a Micro Capillary Zone Electrophoresis System With Integrated Amorphous Silicon Based Optical Detectors

AbstractApplication specific Lab-on-Microchips (ALMs) making use of the combination of complex microfluidic networks with microelectronic circuits and micro optical components allow the realization of miniaturized application specific biological and chemical processing and analysis devices. Fluorescence sensing is one of the most widely used detection technologies, e.g. for DNA fluorescence labelling in Micro Capillary Electrophoresis (µCE) due to its superior sensitivity and specificity. Unfortunately, commercially available fluorescence sensing systems are physically very large, non portable, expensive and constrain the analysis in portable diagnostic and medical care. Integrated semiconductor optoelectronic devices can provide a portable, parallel and inexpensive solution for on chip fluorescence sensing.Most µCE applications working in the spectral range of visible light. For the integration of optical detection components a photon energy range of 1.6 eV - 3.1 eV is of interest. The a-Si:H technology accomplished due to the low dark current and high absorption coefficient against to crystalline silicon the requirements in that spectral range. In this paper we combine a:Si-H photo sensors with a fluidic micro system to detect the fluorescence of a rhodamine analyte mixture. The analyte mixture was excited by light with a wavelength in the range of λEx = 450 - 490 nm. The a-Si:H detector reveals a low dark current density on the order of 10-10 A/cm2 and a sufficient dynamic range of ∼100 dB under illumination of ∼1000 lx as a function of bias voltage. The measurement shows that the movement of the rhodamine plug in the microchannel causes a significant rise in the pin-diode photo current, which correlates to the evaluated signal of a microscope image detector. The photo current difference for excitation and additional fluorescence amounts to 2.4 µA.

Will the Post 9/11 World Be a Post-Tort World?

This essay looks at the impact of 9/11 on provisions for civil recourse by victims of harm. The short answer to the title question is: NO. But tort law will continue to be eroded by attrition, by lopping off remedies - especially by limiting damages and expanding immunities - unless we are able to grab hold of the public's conscience and consciousness to bring home the point that liability in tort is not some form of punishment, erratically inflicted. We discuss and analyze the legislative responses that followed: * the September 11 Victims Compensation Fund * establishment of the World Trade Center Captive Insurance Company to provide defense and excess liability insurance of $1 billion to the City of New York and its contractors. * the smallpox vaccination campaign and the liability limitations and modest compensation scheme of the Smallpox Emergency Personnel Protection Act of 2003. * the adoption of the government contractor defense for suppliers of qualified anti-terrorism technology to the newly created Department of Homeland Security in the SAFETY Act of 2004. * the BioShield Act of 2004 which established a strategic national stockpile of drugs, vaccines and other biological products, medical devices, and other supplies for use in the event of bioterrorist attack or public health emergency. * The Public Readiness and Emergency Preparedness Act of 2005,(PREPA) which declares targeted liability protections for pandemic and epidemic products and security countermeasures. * S. 2291, a bill introduced in 2006 by the Democratic leadership, would repeal the PREPA and create a defense in a narrow class of medical products for which use is permitted without completing the usual regulatory vetting, due to their importance in a threatened emergency. We discuss the ATSSSA, reviewing the strengths and weaknesses of the tort claims of those who were injured and died on 9/11. Next reviewed are the WTC respiratory injury occupational disease tort claims, their necessity and justice, examining their vulnerability in light of the immunity and lack of duty defenses raised. The claims affirm the importance and vigor of the tort remedy. The other post 9/11 liability-limiting legislative measures are discussed. They provide broad protection for many classes of actors and sellers, including administrators and producers of vaccines. A survey of the historic experience with the Swine Flu vaccine campaign of 1976 shows the centrality of familiar tort liability principles of responsibility. In the Swine Flu vaccination the government stood in the shoes of vaccine manufacturers. The United States admitted strict liability in tort for some vaccine complications (such as confirmed paralytic Guillain Barre Syndrome), and fought others. And under the Federal Tort Claims Act the United States defended its own hard sell of the Swine Flu vaccine. Liability was imposed on the United States itself for the Centers for Disease Control's failure to adequately inform citizens of vaccine risks. The British Hepatitis C-contaminated blood cases are discussed as another important instance of government agency liability. There the National Blood Authority was held accountable as collector and distributor of blood products for its tardy implementation of an effective test for viral contamination. First presented as the 2006 Raynes McCarty Distinguished Health Law Lecture, Widener Law School, October 11, 2006

Biomimetic mushroom-shaped fibrillar adhesive microstructure

To improve the adhesive properties of artificial fibrillar contact structures, the attachment systems of beetles from the family Chrysomelidae were chosen to serve as a model. Biomimetic mushroom-shaped fibrillar adhesive microstructure inspired by these systems was characterized using a variety of measurement techniques and compared with a control flat surface made of the same material. Results revealed that pull-off force and peel strength of the structured specimens are more than twice those of the flat specimens. In contrast to the control system, the structured one is found to be very tolerant to contamination and able to recover its adhesive properties after being washed in a soap solution. Based on the combination of several geometrical principles found in biological attachment devices, the presented microstructure exhibits a considerable step towards the development of an industrial dry adhesive.

Biological and Bioinspired Attachment Devices

Chemie Ingenieur TechnikVolume 78, Issue 9 p. 1435-1436 VortragFree Access Biological and Bioinspired Attachment Devices S. Gorb Dr., S. Gorb Dr. s.gorb@mf.mpg.de Evolutionary Biomaterials Group, Max Planck Institute for Metals Research, Heisenbergstraße 3, D-70569 StuttgartSearch for more papers by this author S. Gorb Dr., S. Gorb Dr. s.gorb@mf.mpg.de Evolutionary Biomaterials Group, Max Planck Institute for Metals Research, Heisenbergstraße 3, D-70569 StuttgartSearch for more papers by this author First published: 06 September 2006 https://doi.org/10.1002/cite.200650351AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume78, Issue9Special Issue: GVC/DECHEMA-Jahrestagungen 2006 mit 24. DECHEMA-Jahrestagung der BiotechnologenSeptember, 2006Pages 1435-1436 RelatedInformation

Piezoelectric ink jet processing of materials for medicaland biological applications

Many advanced medical and biological devices require microscale patterning of cells, proteins, and other biological materials. This article describes the use of piezoelectric ink jet processing in the fabrication of biosensors, cell-based assays, and other microscale medical devices. A microelectromechanical system-based piezoelectric transducer was used to develop uniform fluid flow through nozzles and to prepare well-defined microscale patterns of proteins, monofunctional acrylate ester, sinapinic acid, deoxyribonucleic acid (DNA), and DNA scaffolds on relevant substrates. Our results demonstrate that piezoelectric ink jet deposition is a powerful non-contact, non-destructive additive process for developing biosensors, cell culture systems, and other devices for medical and biological applications.