Remote electronic control of DNA hybridization through inductive coupling to an attached metal nanocrystal antenna

Nanorobot for Brain Aneurysm

In this paper we present how nanoelectronics should advance medicine, providing details on the teleoperated techniques and equipment design methodology necessary for the effective development of nanorobots. The platform architecture describes how to use a nanorobot for intracranial prognosis, and shows how it should be integrated for medical instrumentation. Furthermore, the current study establishes proteomics, nanobioelectronics, and electromagnetics as the basis to advance medical nanorobotics. To illustrate the proposed approach, the nanorobots must search for protein overexpression signals in order to recognize initial stages of aneurysm. An advanced nanomechatromics simulator, using a three-dimensional task-based environment, is implemented to provide an effective tool for device prototyping and medical instrumentation analysis. Thus, based on clinical data and nanobioelectronics, the proposed model offers details about how a nanorobot should help with the early detection of cerebral aneurysm.

Remote optical switch for localized and selective control of gene interference

Near infrared-absorbing gold nanoplasmonic particles (GNPs) are used as optical switches of gene interference and are remotely controlled using light. We have tuned optical switches to a wavelength where cellular photodamage is minimized. Optical switches are functionalized with double-stranded oligonucleotides. At desired times and at specific intracellular locations, remote optical excitation is used to liberate gene-interfering oligonucleotides. We demonstrate a novel gene-interfering technique offering spatial and temporal control, which is otherwise impossible using conventional gene-interfering techniques.

The effect of linker length on binding affinity of a photoswitchable molecular glue for DNA

Molecular glue for DNA is a small synthetic ligand that adheres two single-stranded DNAs to produce a double-stranded DNA. We previously devised a photoswitchable molecular glue (PMG) that uses external light stimuli to reversibly control DNA hybridization. To optimize the structure of PMG, we synthesized a series of PMGs and evaluated the effect of changing the methylene linker length on the binding affinity and photoresponse. From the comprehensive T(m) and CSI-TOF-MS measurements, a PMG possessing a three-methylene linker with carbamate linkage produced maximum binding affinity and photoswitching ability. These results indicate that a small difference in the linker can significantly affect PMG function. These findings are useful for designing new photoswitchable DNA-binding ligands.

Protein-templated semiconductor nanoparticle chains

Cadmium sulfide and lead sulfide semiconducting nanoparticle chains have been fabricated for the first time by exploiting a general property of proteins, amyloidogenicity. The diameter of the CdS and PbS nanowires was tuned in the range of ∼50 to ∼350 nm by changing the process parameters. The nanoparticle chains were characterized by field emission scanning electron microscopy, UV-visible spectroscopy, transmission electron microscopy, electron energy loss spectroscopy and high-resolution transmission electron microscopy.

Gel electrophoresis of gold-DNA nanoconjugates

Gold-DNA conjugates were investigated in detail by a comprehensive gel electrophoresis study based on 1200 gels. A controlled number of single-stranded DNA of different length was attached specifically via thiol-Au bonds to phosphine-stabilized colloidal gold nanoparticles. Alternatively, the surface of the gold particles was saturated with single stranded DNA of different length either specifically via thiol-Au bonds or by nonspecific adsorption. From the experimentally determined electrophoretic mobilities, estimates for the effective diameters of the gold-DNA conjugates were derived by applying two different data treatment approaches. The first method is based on making a calibration curve for the relation between effective diameters and mobilities with gold nanoparticles of known diameter. The second method is based on Ferguson analysis which uses gold nanoparticles of known diameter as reference database. Our study shows that effective diameters derived from gel electrophoresis measurements are affected with a high error bar as the determined values strongly depend on the method of evaluation, though relative changes in size upon binding of molecules can be detected with high precision. Furthermore, in this study, the specific attachment of DNA via gold-thiol bonds to Au nanoparticles is compared to nonspecific adsorption of DNA. Also, the maximum number of DNA molecules that can be bound per particle was determined.

Nanorobot Hardware Architecture for Medical Defense

This work presents a new approach with details on the integrated platform and hardware architecture for nanorobots application in epidemic control, which should enable real time in vivo prognosis of biohazard infection. The recent developments in the field of nanoelectronics, with transducers progressively shrinking down to smaller sizes through nanotechnology and carbon nanotubes, are expected to result in innovative biomedical instrumentation possibilities, with new therapies and efficient diagnosis methodologies. The use of integrated systems, smart biosensors, and programmable nanodevices are advancing nanoelectronics, enabling the progressive research and development of molecular machines. It should provide high precision pervasive biomedical monitoring with real time data transmission. The use of nanobioelectronics as embedded systems is the natural pathway towards manufacturing methodology to achieve nanorobot applications out of laboratories sooner as possible. To demonstrate the practical application of medical nanorobotics, a 3D simulation based on clinical data addresses how to integrate communication with nanorobots using RFID, mobile phones, and satellites, applied to long distance ubiquitous surveillance and health monitoring for troops in conflict zones. Therefore, the current model can also be used to prevent and save a population against the case of some targeted epidemic disease.

Neurosurgery in the realm of 10(-9), part 1: stardust and nanotechnology in neuroscience

Nanotechnology as a science has evolved from notions and speculation to emerge as a prominent combination of science and engineering that stands to impact innumerable aspects of technology. Medicine in general and neurosurgery in particular will benefit greatly in terms of improved diagnostic and therapeutic capabilities. The recent explosion in nanotechnology products, including diverse applications such as beauty products and medical contrast agents, has been accompanied by an ever increasing volume of literature. Recent articles from our institution provided an historical and scientific background of nanotechnology, with a purposeful focus on nanomedicine. Future applications of nanotechnology to neuroscience and neurosurgery were briefly addressed. The present article is the first of two that will further this discussion by providing specific details of current nanotechnology applications and research related to neuroscience and clinical neurosurgery. This article also provides relevant perspective in scale, history, economics, and toxicology. Topics of specific importance to developments or advances of technologies used by neuroscientists and neurosurgeons are presented. In addition, advances in the field of microelectromechanical systems technology are discussed. Although larger than nanoscale, microelectromechanical systems technologies will play an important role in the future of medicine and neurosurgery. The second article will discuss current nanotechnologies that are being, or will be in the near future, incorporated into the armamentarium of the neurosurgeon. The goal of these articles is to keep the neuroscience community abreast of current developments in nanotechnology, nanomedicine, and, in particular, nanoneurosurgery, and to present possibilities for future applications of nanotechnology. As applications of nanotechnology permeate all forms of scientific and medical research, clinical applications will continue to emerge. Physicians of the present and future must take an active role in shaping the design and research of nanotechnologies to ensure maximal clinical relevance and patient benefit.

Gold nanostoves for microsecond DNA melting analysis

In traditional DNA melting assays, the temperature of the DNA-containing solution is slowly ramped up. In contrast, we use 300 ns laser pulses to rapidly heat DNA bound gold nanoparticle aggregates. We show that double-stranded DNA melts on a microsecond time scale that leads to a disintegration of the gold nanoparticle aggregates on a millisecond time scale. A perfectly matching and a point-mutated DNA sequence can be clearly distinguished in less than one millisecond even in a 1:1 mixture of both targets.

3D lithographically fabricated nanoliter containers for drug delivery

Lithographic patterning offers the possibility for precise structuring of drug delivery devices. The fabrication process can also facilitate the incorporation of advanced functionality for imaging, sensing, telemetry and actuation. However, a major limitation of present day lithographic fabrication is the inherent two-dimensionality of the patterning process. We review a new approach to construct three dimensional (3D) patterned containers by lithographically patterning two dimensional (2D) templates with liquefiable hinges that spontaneously fold upon heating into hollow polyhedral containers. The containers have finite encapsulation volumes, can be made small enough to pass through a hypodermic needle, and the 3D profile of the containers facilitates enhanced diffusion with the surrounding medium as compared to reservoir systems fabricated in planar substrates. We compare the features of the containers to those of present day drug delivery systems. These features include ease of manufacture, versatility in size and shape, monodisperse porosity, ability for spatial manipulation and remote triggering to release drugs on-demand, the incorporation of electronic modules, cell encapsulation, biocompatibility and stability. We also review possible applications in drug delivery and cell encapsulation therapy (CET). The results summarized in this review suggest a new strategy to enable construction of "smart", three dimensional drug delivery systems using lithography.

A label-free biosensor based on gold nanoshell monolayers for monitoring biomolecular interactions in diluted whole blood

Gold nanoshells (GNSs) were self-assembled on the surface of transparent glasses modified with 3-aminopropyltrimethoxysilane (APTES) to form GNS self-assembled monolayers (SAMs). Because the localized surface plasmon resonance (LSPR) of GNSs can be controlled in the near-infrared (NIR) region of the spectrum, where the optical transmission through tissue and whole blood is optimal, GNSs would be used as an effective signal transduction in whole blood. Accordingly, after modified with cystamine and biotin-NHS (N-hydroxy succinimide), GNS SAMs were used as a novel optical biosensor for real-time detection of streptavidin-biotin interactions in diluted human whole blood within short assay time, without any sample purification/separation. An UV-vis-NIR spectrophotometer was used to monitor the absorbance changes at 730 nm as a function of time for different concentrations of streptavidin in 20% whole blood, and the results showed that the biosensor displayed low detection limit of approximately 3 microg/mL and wide dynamic range of approximately 3-50 microg/mL. This approach provides an opportunity to construct LSPR biosensor for protein sensing and cellular analysis in diluted whole blood.

Local heating of discrete droplets using magnetic porous silicon-based photonic crystals

This paper describes a method for local heating of discrete microliter-scale liquid droplets. The droplets are covered with magnetic porous Si microparticles, and heating is achieved by application of an external alternating electromagnetic field. The magnetic porous Si microparticles consist of two layers. The top layer contains a photonic code and it is hydrophobic, with surface-grafted dodecyl moieties. The bottom layer consists of a hydrophilic silicon oxide host layer that is infused with Fe3O4 nanoparticles. The amphiphilic microparticles spontaneously align at the interface of a water droplet immersed in mineral oil, allowing manipulation of the droplets by application of a magnetic field. Application of an oscillating magnetic field (338 kHz, 18 A rms current in a coil surrounding the experiment) generates heat in the superparamagnetic particles that can raise the temperature of the enclosed water droplet to >80 degrees C within 5 min. A simple microfluidics application is demonstrated: combining complementary DNA strands contained in separate droplets and then thermally inducing dehybridization of the conjugate. The complementary oligonucleotides were conjugated with the cyanine dye fluorophores Cy3 and Cy5 to quantify the melting/rebinding reaction by fluorescence resonance energy transfer (FRET). The magnetic porous Si microparticles were prepared as photonic crystals, containing spectral codes that allowed the identification of the droplets by reflectivity spectroscopy. The technique demonstrates the feasibility of tagging, manipulating, and heating small volumes of liquids without the use of conventional microfluidic channel and heating systems.

Microwave-accelerated metal-enhanced fluorescence: application to detection of genomic and exosporium anthrax DNA in <30 seconds

We describe the ultra-fast and sensitive detection of the gene encoding the protective antigen of Bacillus anthracis the causative agent of anthrax. Our approach employs a highly novel platform technology, Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF), which combines the use of Metal-Enhanced Fluorescence to enhance assay sensitivity and focused microwave heating to spatially and kinetically accelerate DNA hybridization. Genomic and exosporium target DNA of Bacillus anthracis spores was detected within a minute in the nanograms per microliter concentration range using low-power focused microwave heating. The MAMEF technology was able to distinguish between B. anthracis and B. cereus, a non-virulent close relative. We believe that this study has set the stage and indeed provides an opportunity for the ultra-fast and specific detection of B. anthracis spores with minimal pre-processing steps using a relatively simple but cost-effective technology that could minimize casualties in the event of another anthrax attack.

Fluorescence microscopy in a microwave cavity

Optical microscopy is a well-established technique that has wide ranging applications for imaging molecular dynamics of biological systems. Typically, these applications rely on external temperature controllers to maintain or change reactions rates of these biological systems. With increasing interest in applying low power microwaves to drive biological and chemical reactions, we have combined optical and microwave based technologies and developed a fluorescence microscope in a microwave cavity. With this instrument, we have found a means to optically image biological systems inside microwave cavities during the application of microwave pulses.

Biomedical nanotechnology for cancer

Nanotechnology may hold the key to controlling many devastating diseases. In the fight against the pain, suffering, and death due to cancer, nanotechnology will allow earlier diagnosis and even prevention of malignancy at premalignant stages, in addition to providing multimodality treatment not possible with current conventional techniques. This review discusses nanotechnology already used in diagnostic and therapeutic applications for cancer. Also addressed are theoretic and evolving uses of nanotechnology, including multifunctional nanoparticles for imaging and therapy, nanochannel implants for controlled release of drugs, nanoscale devices for evaluation of proteomics and genomics, and diagnostic techniques that take advantage of physical changes in diseased tissue.

Rise of the nanomachine: the evolution of a revolution in medicine

Although the current array of nanomachines mostly comprises simple devices (at least from a mechanical viewpoint), the underlying physical and chemical interactions that play key roles in the ‘assembly’ of these machines have required decades of research to ascertain a fundamental understanding of how such processes can be manipulated at the nanoscale. In this review, we wish to convey a realistic picture of the current developments in the design and implementation of nanomachines, with an emphasis on how these developments are leading to practical applications in medicine, including a sense of how such simple devices are rapidly becoming the building blocks for assembling the nanorobots of tomorrow.

Tunable non-equilibrium gating of flexible DNA nanochannels in response to transport flux

Biological nanochannels made from proteins play a central role in cellular signalling. The rapid emergence of DNA nanotechnology in recent years has opened up the possibility of making similar nanochannels from DNA. Building on previous work on switchable DNA nanocompartment, we have constructed complex DNA nanosystems to investigate the gating behaviour of these nanochannels. Here we show that DNA nanochannels can be gated by stress exerted by permeating solute particles at non-equilibrium states due to the high flexibility of the nanochannels. This novel gating mechanism results in tunable ratchet-like transport of solute particles through the nanochannels. A simple model that couples non-equilibrium channel gating with transport flux can quantitatively explain a number of the phenomena we observe. With only one set of model parameters, we can reproduce diverse gating behaviours, modulated by an inherent gating threshold. This work could lead to the development of new devices based on DNA nanochannels.

Single molecule fluorescence spectroscopy of pH sensitive oligonucleotide switches

Several authors demonstrated that an oligonucleotide based pH-sensitive construct can act as a switch between an open and a closed state by changing the pH. To validate this process, specially designed fluorescence dye-quencher substituted oligonucleotide constructs were developed to probe the switching between these two states. This paper reports on bulk and single molecule fluorescence investigations of a duplex-triplex pH sensitive oligonucleotide switch. On the bulk level, only a partial quenching of the fluorescence is observed, similarly to what is observed for other published switches and is supposed to be due to intermolecular interactions between oligonucleotide strands. On the single molecule level, each DNA-based nanometric construct shows a complete switching. These observations suggest the tendency of the DNA construct to associate at high concentration.

A parallel approach for subwavelength molecular surgery using gene-specific positioned metal nanoparticles as laser light antennas

An optical technique for the parallel manipulation of nanoscale structures with molecular resolution is presented. Bioconjugated metal nanoparticles are thereby positioned at the location of interest, such as, e.g., certain DNA sequences along metaphase chromosomes, prior to pulsed laser light irradiation of the whole sample. The nanoparticles are designed to absorb the introduced energy highly efficiently, in that way acting as nanoantenna. As result of the interaction, structural changes of the sample with subwavelength dimensions and nanoscale precision are observed at the location of the particles. The process leading to the nanolocalized destruction is caused by particle ablation as well as thermal damage of the surrounding material.

Microwave-accelerated ultrafast nanoparticle aggregation assays using gold colloids

In this paper, the proof of principle of microwave-accelerated aggregation assay technology, which shortens the solution-based aggregation assays' run time to seconds (>100-fold increase in kinetics) with microwave heating, was demonstrated using a model aggregation assay based on the well-known interactions of biotin and avidin. Biotinylated gold colloids were aggregated in solution with the addition of streptavidin, which takes 20 min at room temperature to reach >90% completion and only 10 s with microwave heating. The initial velocity (after 1-s microwave heating) of the biotinylated gold colloids reaches up to 10.5 m/s, which gives rise to greater sampling of the total volume but not a large increase in bulk temperature. The room-temperature, steady-state velocity of the colloids was <0.5 microm/s. In control experiments, where streptavidin preincubated with d-biotin in solution is added to biotinylated gold colloids and microwave heated, gold colloids did not aggregate, demonstrating that nonspecific interactions between biotinylated gold colloids and streptavidin were negligible.

Efficient manipulation of nanoparticle-bound DNA via restriction endonuclease

As a programmable biopolymer, DNA has shown great potential in the fabrication and construction of nanometer-scale assemblies and devices. In this report, we described a strategy for efficient manipulation of gold nanoparticle-bound DNA using restriction endonuclease. The digestion efficiency of this restriction enzyme was studied by varying the surface coverage of stabilizer, the size of nanoparticles, as well as the distance between the nanoparticle surface and the enzyme-cutting site of particle-bound DNA. We found that the surface coverage of stabilizer is crucial for achieving high digestion efficiency. In addition, this stabilizer surface coverage can be tailored by varying the ion strength of the system. Based on the results of polyacrylamide gel electrophoresis and fluorescent study, a high digestion efficiency of 90+% for particle-bound DNA was achieved for the first time. This restriction enzyme manipulation can be considered as an additional level of control of the particle-bound DNA and is expected to be applied to manipulate more complicated nanostructures assembled by DNA.

Colorimetric multiplexed immunoassay using specific aggregation of antigenic peptide-modified luminous nanoparticles

A rapid immunoassay capable of detecting specific antibodies in one-step procedure is described. Antigenic peptides with cationic (KKKKC) or anionic (DDDDC) pentamer tail were immobilized on luminous nanospheres of 40 nm diameter (Ø) through cystamine and bifunctional linker molecules under various conditions. The numbers of each peptide anchored to a sphere were 5.0 x 10(2) and 0.8-3.8 x 10(3), respectively. A mixture of the antigenic peptides of FAK and c-Myc was immobilized to the spheres with red emission, while that of c-Myc and alpha-catenin was likewise to green spheres. Multiplexed immunoassay was easily achieved by adding the antibodies to a mixed dispersed solution of these spheres under appropriate conditions. Anti-FAK and anti-alpha-catenin antibodies formed aggregates with red and green emissions, respectively. On the other hand, the anti-c-Myc antibody formed aggregates emitting a yellow light. This system enabled us to differentiate three antibodies in one vessel from the definite differences in aggregate color.

Nanosecond responses of proteins to ultra-high temperature pulses

Observations of fast unfolding events in proteins are typically restricted to <100 degrees C. We use a novel apparatus to heat and cool enzymes within tens of nanoseconds to temperatures well in excess of the boiling point. The nanosecond temperature spikes are too fast to allow water to boil but can affect protein function. Spikes of 174 degrees C for catalase and approximately 290 degrees C for horseradish peroxidase are required to produce irreversible loss of enzyme activity. Similar temperature spikes have no effect when restricted to 100 degrees C or below. These results indicate that the "speed limit" for the thermal unfolding of large proteins is shorter than 10(-8) s. The unfolding rate at high temperature is consistent with extrapolation of low temperature rates over 12 orders of magnitude using the Arrhenius relation.

Profluorescent protein fragments for fast bimolecular fluorescence complementation in vitro

Here, we present a protocol for isolating the large N-terminal fragment of enhanced green fluorescent protein (EGFP) with a preformed chromophore. By itself, the chromophore-containing EGFP fragment exhibits very weak fluorescence, but it rapidly becomes brightly fluorescent upon complementation with the corresponding small, C-terminal EGFP fragment. Each EGFP fragment is cloned and overexpressed in E. coli as a fusion with self-splitting intein. After solubilizing and refolding these fusions from inclusion bodies, both EGFP fragments are cleaved from intein and purified using chitin columns. When these EGFP fragments are linked with the two complementary oligonucleotides and combined in equimolar amounts, fluorescence develops within a few minutes. The isolation of profluorescent protein fragments from recombinant E. coli cells requires approximately 3 d, and their conjugation to oligonucleotides requires 1-4 h.

Evidence for a specific microwave radiation effect on the green fluorescent protein

We have compared the effect of microwave irradiation and of conventional heating on the fluorescence of solution-based green fluorescent protein. A specialized near-field 8.5 GHz microwave applicator operating at 250 mW input microwave power was used. The solution temperature, the intensity, and the spectrum of the green fluorescent protein fluorescence 1), under microwave irradiation and 2), under conventional heating, were measured. In both cases the fluorescence intensity decreases and the spectrum becomes red-shifted. Although the microwave irradiation heats the solution, the microwave-induced changes in fluorescence cannot be explained by heating alone. Several possible scenarios are discussed.

Distance-dependent fluorescence quenching on gold nanoparticles ensheathed with layer-by-layer assembled polyelectrolytes

We report on the preparation, characterization, and photophysical study of new fluorescent core/shell nanoparticles fabricated by electrostatic layer-by-layer assembly. On the basis of gold cores with a diameter of 13 nm, these nanocolloids possess different fluorescently labeled polymer corona layers at various distances from the surface of the core metal using nonfluorescent polyelectrolytes as spacer layers. UV-visible spectroscopy and transmission electron microscopy confirm that the particle suspensions of fluorescently labeled core/shell nanoparticles are stable at all stages of their construction. Photophysical investigations reveal strongly distance-dependent fluorescence quenching in these particle systems. The contribution of the metal core to this quenching can be assesed precisely after the gentle dissolution of the gold cores by potassium cyanide. The photophysical measurements reveal clearly that the gold nanoparticles decrease the transition probability for radiative transitions.