Ultrafast and Controlled Capturing, Loading, and Release of Extracellular Vesicles by a Portable Microstructured Electrochemical Fluidic Device.

Extracellular vesicles (EVs) are secreted by all living cells and are found in body fluids. They exert numerous physiological and pathological functions and serve as cargo shuttles. Due to their safety and inherent bioactivity, they have emerged as versatile therapeutic agents, biomarkers, and potential drug carriers. Despite the growing interest in EVs, current progress in this field is, in part, limited by relatively inefficient isolation techniques. Conventional methods are indeed slow, laborious, require specialized laboratory equipment, and may result in low yield and purity. This work describes an electrochemically controlled "all-in-one" device enabling capturing, loading, and releasing of EVs. The device is composed of a fluidic channel confined within antibody-coated microstructured electrodes. It rapidly isolates EVs with a high level of purity from various biofluids. As a proof of principle, the device is applied to isolate EVs from skin wounds of healthy and diabetic mice. Strikingly, it is found that EVs from healing wounds of diabetic mice are enriched in mitochondrial proteins compared to those of healthy mice. Additionally, the device improves the loading protocol of EVs with polyplexes, and may therefore find applications in nucleic acid delivery. Overall, the electrochemical device can greatly facilitate the development of EVs-based technologies.

Sulfonated Amphiphilic Poly(α)glutamate Amine-A Potential siRNA Nanocarrier for the Treatment of Both Chemo-Sensitive and Chemo-Resistant Glioblastoma Tumors.

Development of chemo-resistance is a major challenge in glioblastoma (GB) treatment. This phenomenon is often driven by increased activation of genes associated with DNA repair, such as the alkyl-removing enzyme O6-methylguanine-DNA methyltransferase (MGMT) in combination with overexpression of canonical genes related to cell proliferation and tumor progression, such as Polo-like kinase 1 (Plk1). Hereby, we attempt to sensitize resistant GB cells using our established amphiphilic poly(α)glutamate (APA): small interfering RNA (siRNA) polyplexes, targeting Plk1. Furthermore, we improved brain-targeting by decorating our nanocarrier with sulfonate groups. Our sulfonated nanocarrier showed superior selectivity towards P-selectin (SELP), a transmembrane glycoprotein overexpressed in GB and angiogenic brain endothelial cells. Self-assembled polyplexes of sulfonated APA and siPlk1 internalized into GB cells and into our unique 3-dimensional (3D) GB spheroids inducing specific gene silencing. Moreover, our RNAi nanotherapy efficiently reduced the cell viability of both chemo-sensitive and chemo-resistant GB cells. Our developed sulfonated amphiphilic poly(α)glutamate nanocarrier has the potential to target siRNA to GB brain tumors. Our findings may strengthen the therapeutic applications of siRNA for chemo-resistant GB tumors, or as a combination therapy for chemo-sensitive GB tumors.

Clinic-on-a-Needle Array toward Future Minimally Invasive Wearable Artificial Pancreas Applications.

In order to reduce medical facility overload due to the rise of the elderly population, modern lifestyle diseases, or pandemics, the medical industry is currently developing point-of-care and home medical device systems. Diabetes is an incurable and lifetime disease, accountable for a significant mortality and socio-economic public health burden. Thus, tight glucose control in diabetic patients, which can prevent the onset of its late complications, is of enormous importance. Despite recent advances, the current best achievable management of glucose control is still inadequate, due to several key limitations in the system components, mainly related to the reliability of sensing components, both temporally and chemically, and the integration of sensing and delivery components in a single wearable platform, which is yet to be achieved. Thus, advanced closed-loop artificial pancreas systems able to modulate insulin delivery according to the measured sensor glucose levels, independently of patient supervision, represent a key requirement of development efforts. Here, we demonstrate a minimally invasive, transdermal, multiplex, and versatile continuous metabolites monitoring system in the subcutaneous interstitial fluid space based on a chemically modified SiNW-FET nanosensor array on microneedle elements. Using this technology, ISF-borne metabolites require no extraction and are measured directly and continuously by the nanosensors. Due to their chemical sensing mechanism, the nanosensor response is only influenced by the specific metabolite of interest, and no response is observed in the presence of potential exogenous and endogenous interferents known to seriously affect the response of current electrochemical glucose detection approaches. The 2D architecture of this platform, using a single SOI substrate as a top-down multipurpose material, resulted in a standard fabricated chip with 3D functionality. After proving the ability of the system to act as a selective multimetabolites sensor, we have implemented our platform to reach our main goal for in vivo continuous glucose monitoring of healthy human subjects. Furthermore, minor adjustments to the fabrication technique allow the on-chip integration of microinjection needle elements, which can ideally be used as a drug delivery system. Preliminary experiments on a mice animal model successfully demonstrated the single-chip capability to both monitor glucose levels as well as deliver insulin. By that, we hope to provide in the future a cost-effective and reliable wearable personalized clinical tool for patients and a strong tool for research, which will be able to perform direct monitoring of clinical biomarkers in the ISF as well as synchronized transdermal drug delivery by this single-chip multifunctional platform.

Rapid Collection and Aptamer-Based Sensitive Electrochemical Detection of Soybean Rust Fungi Airborne Urediniospores.

Plants are the central source of food for humans around the world. Unfortunately, plants can be negatively affected by diverse kinds of diseases that are responsible for major economic losses worldwide. Thus, monitoring plant health and early detection of pathogens are essential to reduce disease spread and facilitate effective management practices. Various detection approaches are currently practiced. These methods mainly include visual inspection and laboratory tests. Nonetheless, these methods are labor-intensive, time-consuming, expensive, and inefficient in the early stages of infection. Thus, it is extremely important to detect diseases at the early stages of the epidemic. Here, we would like to present a fast, sensitive, and reliable electrochemical sensing platform for the detection of airborne soybean rust spores. The suspected airborne soybean rust spores are first collected and trapped inside a carbon 3D electrode matrix by high-capacity air-sampling means. Then, a specific biotinylated aptamer, suitable to target specific sites of soybean rust spores is applied. This aptamer agent binds to the surface of the collected spores on the electrode. Finally, spore-bound aptamer units are incubated with a streptavidin-alkaline phosphatase agent leading to the enzymatic formation of p-nitrophenol, which is characterized by its unique electrochemical properties. Our method allows for the rapid (ca. 2 min), selective, and sensitive collection and detection of soybean rust spores (down to the limit of 100-200 collected spores per cm2 of electrode area). This method could be further optimized for its sensitivity and applied to the future multiplex early detection of various airborne plant diseases.

Ultrafast high-capacity capture and release of uranium by a light-switchable nanotextured surface.

Nuclear power is growing in demand as a promising sustainable energy source, its most prevalent source being uranium salts. The resulting processing and transportation of uranium raise concerns regarding the environmental impact and risks for human health. Close proximity to uranium mines puts populations at higher risk for exposure due to elevated uranium concentrations. As the main form of uranium in aqueous solutions, uranyl (UO2 2+) has been the focus of many methods of uranium sieving; most fall short by being time-consuming or lacking a retrieval mechanism for the captured uranium. Here, we demonstrate the ultrafast and selective uranyl-capturing properties of aptamer-modified branched silicon nanopillar (BSiNP) arrays. Our nanostructured surfaces demonstrate an ultrahigh surface area modified with a uranyl-specific DNA aptamer, allowing for high uranyl-capturing capacity, reaching up to 550 mg g-1. Uranyl capture is followed by the activation of a covalently bonded photoacid, causing a light-triggerable, ultrafast release. This capture-and-release cycle results in the collection of over 70% of the uranium found in the original samples within less than one hour.

Direct whole blood analysis by the antigen-antibody chemically-delayed dissociation from nanosensors arrays.

A wide range of fields, starting from basic research in life sciences and up to medical applications, are highly interested in the investigation and detection of biomarkers in all their forms, including proteins. However, direct analytical detection of specific protein biomarkers from a physiological biosample is still extremely challenging due to the abundant variety and amount of its components. In this work, we apply the chemically-controlled antigen-dissociation detection approach on silicon nanowires-based field-effect transistor arrays, by creating a suitable 'chemical environment' which enabled the clear-cut splitting of the dissociation regime window into two sub-regimes, thus allowing the complete washing of the nonspecifically adsorbed salts and biomolecules, while significantly delaying the dissociation of specific surface-bounded antigen-antibody pairs. This was accomplished by the addition of the water-miscible organic reagent ethylene glycol, which radically alters the properties of the aqueous solvent, by means of dramatically reducing its interactions with the particular protein antigen, and thus allowing for the increase in the antigen-antibody interaction strength. This in turn, deeply reduces the solubility of the surface-bound protein molecules and increases their interaction with the specific receptor antibody units, which brings to a substantial delay in the antibody-antigen dissociation behavior. This phenomenon allows the clear-cut splitting of the dissociation regime window and the quantitative and accurate analysis of proteins in physiological samples. We demonstrated the direct and quantitative detection of protein biomarkers, down to concentrations in the fM range, from unprocessed whole blood minuscule samples of only a few microliters. This work is the first demonstration on the chemically-controlled dissociation kinetics of antibody-antigen pairs by the use of water-miscible organic solvent mixtures, and its application in the direct ultrasensitive detection of protein biomarkers from whole blood samples.

Direct Detection of Uranyl in Urine by Dissociation from Aptamer-Modified Nanosensor Arrays.

An ever-growing demand for uranium in various industries raises concern for human health of both occupationally exposed personnel and the general population. Toxicological effects related to uranium (natural, enriched, or depleted uranium) intake involve renal, pulmonary, neurological, skeletal, and hepatic damage. Absorbed uranium is filtered by the kidneys and excreted in the urine, thus making uranium detection in urine a primary indication for exposure and body burden assessment. Therefore, the detection of uranium contamination in bio-samples (urine, blood, saliva, etc.,) is of crucial importance in the field of occupational exposure and human health-related applications, as well as in nuclear forensics. However, the direct determination of uranium in bio-samples is challenging because of "ultra-low" concentrations of uranium, inherent matrix complexity, and sample diversity, which pose a great analytical challenge to existing detection methods. Here, we report on the direct, real-time, sensitive, and selective detection of uranyl ions in unprocessed and undiluted urine samples using a uranyl-binding aptamer-modified silicon nanowire-based field-effect transistor (SiNW-FET) biosensor, with a detection limit in the picomolar concentration range. The aptamer-modified SiNW-FET presented in this work enables the simple and sensitive detection of uranyl in urine samples. The experimental approach has a straight-forward implementation to other metals and toxic elements, given the availability of target-specific aptamers. Combining the high surface-to-volume ratio of SiNWs, the high affinity and selectivity of the uranyl-binding aptamer, and the distinctive sensing methodology gives rise to a practical platform, offering simple and straightforward sensing of uranyl levels in urine, suitable for field deployment and point-of-care applications.

Real-time monitoring of bacterial biofilms metabolic activity by a redox-reactive nanosensors array.

BACKGROUND: Bacterial biofilms are communities of surface-associated microorganisms living in cellular clusters or micro-colonies, encapsulated in a complex matrix composed of an extracellular polymeric substance, separated by open water channels that act as a circulatory system that enable better diffusion of nutrients and easier removal of metabolic waste products. The monitoring of biofilms can provide important information on fundamental biofilm-related processes. That information can shed light on the bacterial processes and enable scientists to find ways of preventing future bacterial infections. Various approaches in use for biofilm analysis are based on microscopic, spectrochemical, electrochemical, and piezoelectrical methods. All these methods provide significant progress in understanding the bio-process related to biofilm formation and eradication, nevertheless, the development of novel approaches for the real-time monitoring of biochemical, in particular metabolic activity, of bacterial species during the formation, life and eradication of biofilms is of great potential importance. RESULTS: Here, detection and monitoring of the metabolic activity of bacterial biofilms in high-ionic-strength solutions were enabled as a result of novel surface modification by an active redox system, composed of 9,10-dihydroxyanthracene/9,10-anthraquinone, on the oxide layer of the SiNW, yielding a chemically-gated FET array. With the use of enzymatic reactions of oxidases, metabolites can be converted to H2O2 and monitored by the nanosensors. Here, the successful detection of glucose metabolites in high-ionic-strength solutions, such as bacterial media, without pre-processing of small volume samples under different conditions and treatments, has been demonstrated. The biofilms were treated with antibiotics differing in their mechanisms of action and were compared to untreated biofilms. Further examination of biofilms under antibiotic treatment with SiNW-FET devices could shed light on the bioprocess that occurs within the biofilm. Moreover, finding proper treatment that eliminates the biofilm could be examined by the novel nanosensor as a monitoring tool. CONCLUSIONS: To summarize, the combination of redox-reactive SiNW-FET devices with micro-fluidic techniques enables the performance of rapid, automated, and real-time metabolite detection with the use of minimal sample size, noninvasively and label-free. This novel platform can be used as an extremely sensitive tool for detection and establishing medical solutions for bacterial-biofilm eradication and for finding a proper treatment to eliminate biofilm contaminations. Moreover, the sensing system can be used as a research tool for further understanding of the metabolic processes that occur within the bacterial biofilm population.

Redox-Reactive Field-Effect Transistor Nanodevices for the Direct Monitoring of Small Metabolites in Biofluids toward Implantable Nanosensors Arrays.

Chemically modified field-effect transistor (FET) nanodevices were shown to be a selective and extremely sensitive detection platform. In FET-based sensors, signal amplification and transduction is based on electrostatic gating of the nanometric semiconductor channel by analyte-receptor interactions, which measurably affect the transconductance of the device. However, chemically modified FETs must overcome several fundamental limitations before they can be effectively deployed as real-time sensors for bioevents occurring on their surface in complex biofluids. Here, we demonstrate the development of amperoFET devices for the real-time continuous monitoring of small molecular metabolites in biofluids. The surface of the nanowires is covalently modified with a redox reversible moiety, which is easily oxidized in the presence of H2O2. The reversible redox transformation of the surface-confined molecules is carried out by a hot electron injection mechanism, conducted simply by the modulation of the source-drain current through the nanoFET sensing device. By this approach, electrons may be injected by the nanowire element into the surface-confined redox moiety and thus maintain a whole-electrically actuated redox system in which the oxidation state is completely controlled by the current applied to the amperoFET system. The modulation of the source-drain current allows the control of the reduced versus oxidized redox moieties population on the nanowire surface, and this, in turn, is applied as the main sensing mechanism. At a given constant source-drain and gate voltage, the chemical perturbation exerted by the presence of chemical oxidants in the tested biofluid will lead to a measurable conductance change. Alteration in the concentration of the specific metabolite will chemically regulate the extent of perturbation applied to the redox system, which can be utilized for the quantification of the molecular metabolite of interest. These 'equilibrium'-type sensors are fully electrically operated and can be further used in implantable sensing applications.

Vapor Trace Collection and Direct Ultrasensitive Detection of Nitro-Explosives by 3D Microstructured Electrodes.

The development of a rapid, sensitive, and selective real-time detection method for explosives traces may have an enormous impact on civilian national security, military applications, and environmental monitoring. However, real-time sensing of explosives still possesses a huge analytical hurdle, rendering explosives detection an issue of burning immediacy and an enormous current challenge in terms of research and development. Even though several explosives detection methods have been established, these approaches are typically time-consuming, need relatively large equipment, demand sample preparation, require a skilled operator, and lack the capability to do high-throughput real-time detection, thus strongly constraining their mass deployment. Here, we demonstrate the use of amino-modified carbon microfiber (µCF) working electrodes for ultrasensitive, selective, and multiplex detection of nitro-based explosives. Furthermore, our sensing method works at high sampling rates by a single electrode in a single detection cycle. We hereby present the first demonstration of porous µCF electrodes used for the simultaneous collection/preconcentration of explosive molecular species through direct air sampling, followed by the electrochemical detection of the surface adsorbed electroactive species. Our chemically modified µCF electrodes allow straightforward vapor-phase detection and discrimination of multiple nitro-based explosives directly from collected air samples. Hence, our sensing approach has been shown highly effective in the ultratrace detection of nitro-based explosives, under real-world conditions.

Light-Controlled Selective Collection-and-Release of Biomolecules by an On-Chip Nanostructured Device.

The analysis of biosamples, e.g., blood, is a ubiquitous task of proteomics, genomics, and biosensing fields; yet, it still faces multiple challenges, one of the greatest being the selective separation and detection of target proteins from these complex biosamples. Here, we demonstrate the development of an on-chip light-triggered reusable nanostructured selective and quantitative protein separation and preconcentration platform for the direct analysis of complex biosamples. The on-chip selective separation of required protein analytes from raw biosamples is performed using antibody-photoacid-modified Si nanopillars vertical arrays (SiNPs) of ultralarge binding surface area and enormously high binding affinity, followed by the light-controlled rapid release of the tightly bound target proteins in a controlled liquid media. Two important experimental observations are presented: (1) the first demonstration on the control of biological reaction binding affinity by the nanostructuring of the capturing surface, leading to highly efficient protein collection capabilities, and (2) the light-triggered switching of the highly sticky binding surfaces into highly reflective nonbinding surfaces, leading to the rapid and quantitative release of the originally tightly bound protein species. Both of these two novel behaviors were theoretically and experimentally investigated. Importantly, this is the first demonstration of a three-dimensional (3D) SiNPs on-chip filter with ultralarge binding surface area and reversible light-controlled quantitative release of adsorbed biomolecules for direct purification of blood samples, able to selectively collect and separate specific low abundant proteins, while easily removing unwanted blood components (proteins, cells) and achieving desalting results, without the requirement of time-consuming centrifugation steps, the use of desalting membranes, or affinity columns.

Cellular Metabolomics by a Universal Redox-Reactive Nanosensors Array: From the Cell Level to Tumor-on-a-Chip Analysis.

Although biosensors based on nanowires-field effect transistor were proved extraordinarily efficient in fundamental applications, screening of charges due to the high-ionic strength of most physiological solutions imposes severe limitations in the design of smart, "real-time" sensors, as the biosample solution has to be previously desalted. This work describes the development of a novel nanowire biosensor that performs extracellular real-time multiplex sensing of small molecular metabolites, the true indicators of the body's chemistry machinery, without any preprocessing of the biosample. Unlike other nanoFET devices that follow direct binding of analytes to their surfaces, our nanodevice acts by sensing the oxidation state of redox-reactive chemical species bound to its surface. The device's surface array is chemically modified with a reversible redox molecular system that is sensitive to H2O2 down to 100 nM, coupled with a suite of corresponding oxidase enzymes that convert target metabolites to H2O2, enabling the direct prompt analysis of complex biosamples. This modality was successfully demonstrated for the real-time monitoring of cancer cell samples' metabolic activity and evaluating chemotherapeutic treatment options for cancer. This distinctive system displays ultrasensitive, selective, noninvasive, multiplex, real-time, label-free, and low-cost sensing of small molecular metabolites in ultrasmall volumes of complex biosamples, in the single-microliter scale, placing our technology at the forefront of this cutting-edge field.

Direct and Selective Electrochemical Vapor Trace Detection of Organic Peroxide Explosives via Surface Decoration.

The ability to detect traces of highly energetic explosive materials sensitively, selectively, accurately, and rapidly could be of enormous benefit to civilian national security, military applications, and environmental monitoring. Unfortunately, the detection of explosives still poses a largely unmet arduous analytical problem, making their detection an issue of burning immediacy and a massive current challenge in terms of research and development. Although numerous explosive detection approaches have been developed, these methods are usually time-consuming, require bulky equipment, tedious sample preparation, a trained operator, cannot be miniaturized, and lack the ability to perform automated real-time high-throughput analysis, strongly handicapping their mass deployment. Here, we present the first demonstration of the "direct" electrochemical approach for the sensitive, selective, and rapid vapor trace detection of TATP and HMTD, under ambient conditions, unaffected by the presence of oxygen and hydrogen peroxide species, down to concentrations lower than 10 ppb. The method is based on the use of Ag-nanoparticles-decorated carbon microfibers air-collecting electrodes (µCF), which allow for the selective direct detection of the organic peroxide explosives, through opening multiple redox routes, not existent in the undecorated carbon electrodes. Finally, we demonstrate the direct and rapid detection of TATP and HMTD explosive species from real-world air samples.

Molecular Weight-Dependent Activity of Aminated Poly(α)glutamates as siRNA Nanocarriers.

RNA interference (RNAi) can contribute immensely to the area of personalized medicine by its ability to target any gene of interest. Nevertheless, its clinical use is limited by lack of efficient delivery systems. Polymer therapeutics can address many of the challenges encountered by the systemic delivery of RNAi, but suffer from inherent drawbacks such as polydispersity and batch to batch heterogeneity. These characteristics may have far-reaching consequences when dealing with therapeutic applications, as both the activity and the toxicity may be dependent on the length of the polymer chain. To investigate the consequences of polymers' heterogeneity, we have synthesized two batches of aminated poly(α)glutamate polymers (PGAamine), differing in their degree of polymerization, but not in the monomer units or their conjugation. Isothermal titration calorimetry study was conducted to define the binding affinity of these polymers with siRNA. Molecular dynamics simulation revealed that Short PGAamine:siRNA polyplexes exposed a higher amount of amine moieties to the surroundings compared to Long PGAamine. This resulted in a higher zeta potential, leading to faster degradation and diminished gene silencing. Altogether, our study highlights the importance of an adequate physico-chemical characterization to elucidate the structure⁻function-activity relationship, for further development of tailor-designed RNAi delivery vehicles.

Multicolor Spectral-Specific Silicon Nanodetectors based on Molecularly Embedded Nanowires.

Silicon-based photodetectors cannot distinguish between different wavelengths. Therefore, these detectors relay on color-specific filters to achieve color separation. Color filters add complexity to color sensitive device fabrication, and hinder miniaturization of such devices. Here, we report an ultrasmall (as small as ∼20 nm by 300 nm), red-green-blue-violet (RGBV) filter-free spectrally gated field effect transistor (SGFET) detectors. These photodetectors are based on organic-silicon nanowire hybrid FET devices, capable of detecting specific visible wavelength spectrum with full width at half-maxima (fwhm) under 100 nm. Each SGFET is controlled by a distinctive RGBV spectral range, according to its specific organic fluorophore functionalization. The spectral-specific RGBV detection is accomplished via covalent attachment of different fluorophores. The fluorophore molecules inject electrons into the nanowire structure as a result of light absorption at the appropriate RGBV spectral range. These photoinduced electrons modify the occupancies of the oxide's surface states, shifting the device threshold voltage, thus changing its conductivity, and functioning as a negative stress bias in a p-type SiNW FETs. A positive biasing can be achieved via UV light-induced ionization, which leads to detrapping and translocation of electrons at the oxide layer. Furthermore, a novel theoretical model on the mechanism of action of these devices was developed. Also, we show that suspended SGFETs can function as nonvolatile memory elements, which unlike fast-relaxing on-surface SGFETs, can store discrete "on" (RGBV illumination) and "off" (UV illumination) states for several days at ambient conditions. We also demonstrate a unique single-nanowire multicolor photodetector, enabling in principle a broad spectral detection over a single silicon nanowire element. These highly compact, spectral-controlled nanodevices have the potential to serve in various future novel optoelectric applications.

Antigen-Dissociation from Antibody-Modified Nanotransistor Sensor Arrays as a Direct Biomarker Detection Method in Unprocessed Biosamples.

The detection of biomolecules is critical for a wide spectrum of applications in life sciences and medical diagnosis. Nonetheless, biosamples are highly complex solutions, which contain an enormous variety of biomolecules, cells, and chemical species. Consequently, the intrinsic chemical complexity of biosamples results in a significant analytical background noise and poses an immense challenge to any analytical measurement, especially when applied without prior efficient separation and purification steps. Here, we demonstrate the application of antigen-dissociation regime, from antibody-modified Si-nanowire sensors, as a simple and effective direct sensing mechanism of biomarkers of interest in complex biosamples, such as serum and untreated blood, which does not require ex situ time-consuming biosample manipulation steps, such as centrifugation, filtering, preconcentration, and desalting, thus overcoming the detrimental Debye screening limitation of nanowire-based biosensors. We found that two key parameters control the capability to perform quantitative biomarkers analysis in biosamples: (i) the affinity strength (koff rate) of the antibody-antigen recognition pair, which dictates the time length of the high-affinity slow dissociation subregime, and (ii) the "flow rate" applied during the solution exchange dissociation step, which controls the time width of the low-affinity fast-dissociation subregime. Undoubtedly, this is the simplest and most convenient approach for the SiNW FET-based detection of antigens in complex untreated biosamples. The lack of ex situ biosample manipulation time-consuming processes enhances the portability of the sensing platform and reduces to minimum the required volume of tested sample, as it allows the direct detection of untreated biosamples (5-10 µL blood or serum), while readily reducing the detection cycle duration to less than 5 min, factors of great importance in near-future point-of-care medical applications. We believe this is the first ever reported demonstration on the real-time, direct label-free sensing of biomarkers from untreated blood samples, using SiNW-based FET devices, while not compromising the ultrasensitive sensing capabilities inherent to these devices.

Structure-Function Correlation of Aminated Poly(α)glutamate as siRNA Nanocarriers.

It has been two decades since cationic polymers were introduced to the world of oligonucleotides delivery. However, the optimal physicochemical properties to make them a successful delivery vehicle are yet unknown. An ideal system became particularly interesting and necessary with the introduction of RNA interference as a promising therapeutic approach. Such nanocarrier should overcome challenges such as low plasma stability, poor cellular internalization and endosomal escape to induce gene silencing. To that end, we synthesized a library of biodegradable aminated poly(α)glutamate varied by amine moieties. In an attempt to elucidate the structure-function relationship, our polyplexes were physicochemically characterized and their silencing activity and cytotoxicity were evaluated. We found several structures that demonstrated improved cellular internalization. These candidates silenced gene expression to less than 50% of their initial levels, while being safe to cells and mice. Based on our research, an improved and promising tailor-designed siRNA delivery platform can be developed.

Supersensitive fingerprinting of explosives by chemically modified nanosensors arrays.

The capability to detect traces of explosives sensitively, selectively and rapidly could be of great benefit for applications relating to civilian national security and military needs. Here, we show that, when chemically modified in a multiplexed mode, nanoelectrical devices arrays enable the supersensitive discriminative detection of explosive species. The fingerprinting of explosives is achieved by pattern recognizing the inherent kinetics, and thermodynamics, of interaction between the chemically modified nanosensors array and the molecular analytes under test. This platform allows for the rapid detection of explosives, from air collected samples, down to the parts-per-quadrillion concentration range, and represents the first nanotechnology-inspired demonstration on the selective supersensitive detection of explosives, including the nitro- and peroxide-derivatives, on a single electronic platform. Furthermore, the ultrahigh sensitivity displayed by our platform may allow the remote detection of various explosives, a task unachieved by existing detection technologies.

Si nanowires forest-based on-chip biomolecular filtering, separation and preconcentration devices: nanowires do it all.

The development of efficient biomolecular separation and purification techniques is of critical importance in modern genomics, proteomics, and biosensing areas, primarily due to the fact that most biosamples are mixtures of high diversity and complexity. Most of existent techniques lack the capability to rapidly and selectively separate and concentrate specific target proteins from a complex biosample, and are difficult to integrate with lab-on-a-chip sensing devices. Here, we demonstrate the development of an on-chip all-SiNW filtering, selective separation, desalting, and preconcentration platform for the direct analysis of whole blood and other complex biosamples. The separation of required protein analytes from raw biosamples is first performed using a antibody-modified roughness-controlled SiNWs (silicon nanowires) forest of ultralarge binding surface area, followed by the release of target proteins in a controlled liquid media, and their subsequent detection by supersensitive SiNW-based FETs arrays fabricated on the same chip platform. Importantly, this is the first demonstration of an all-NWs device for the whole direct analysis of blood samples on a single chip, able to selectively collect and separate specific low abundant proteins, while easily removing unwanted blood components (proteins, cells) and achieving desalting effects, without the requirement of time-consuming centrifugation steps, the use of desalting or affinity columns. Futhermore, we have demonstrated the use of our nanowire forest-based separation device, integrated in a single platform with downstream SiNW-based sensors arrays, for the real-time ultrasensitive detection of protein biomarkers directly from blood samples. The whole ultrasensitive protein label-free analysis process can be practically performed in less than 10 min.