Enhanced Internalization of Indian Ayurvedic Swarna Bhasma (Gold Nanopowder) for Effective Interaction with Human Cells

In the ancient traditional Indian Ayurvedic system of natural healing, gold nanoparticles (Swarna Bhasma, gold ash) have been used for its therapeutic benefits as far back as 2500 B.C. Ayurvedic medicinal preparations are complex mixtures that include many plant-derived products and metals. Bhasmas date as far back as the 8th century and are made by samskaras (processings), such as shodhana (purification and potentiation), jarana (roasting), and marana (incineration, trituration) in the presence of plant products, including juices and concoctions. Previous studies characterized the physical properties of gold ash, and the mechanisms of its entry into human cells, but only preliminary data exist on its toxicity. Before using nanoparticles for therapeutic application, it is extremely important to study their toxicity and cellular internalization. In the present study, various imaging techniques were used to investigate Swarna Bhasma's (gold nanopowder) toxicity in both cancerous and noncancerous cells (HeLa and HFF-1) and to characterize its spectral properties. The results showed that gold ash particles had no impact on the cellular viability of both HeLa and HFF-1 cells, even at high concentrations or long incubation times. Moreover, it was found that the internalization level of Swarna Bhasma to cells may be improved by mechanical breaking of the large aggregates into smaller agglomerates. Hyperspectral images revealed that after breaking, the small agglomerates have different spectral properties in cells, compared to the original aggregates, suggesting that size of particles is instrumental for the subcellular interaction with human cells.

Flow force augmented 3D suspended polymeric microfluidic (SPMF3 ) platform

Detection and study of bioelements using microfluidic systems has been of great interest in the biodiagnostics field. Microcantilevers are the most used systems in biodetection due to their implementation simplicity which have been used for a wide variety of applications ranging from cellular to molecular diagnosis. However, increasing further the sensitivity of the microcantilever systems have a great effect on the cantilever based sensing for chemical and bio applications. In order to improve further the performance of microcantilevers, a flow force augmented 3D suspended microchannel is proposed using which microparticles can be conveyed through a microchannel inside the microcantilever to the detection area. This innovative microchannel design addresses the low sensitivity issue by increasing its sensitivity up to 5 times than the earlier reported similar microsystems. Moreover, fabricating this microsystem out of Polydimethylsiloxane (PDMS) would eliminate external exciter dependency in many detection applications such as biodiagnostics. In this study, the designed microsystem has been analyzed theoretically, simulated and tested. Moreover, the microsystem has been fabricated and tested under different conditions, the results of which have been compared with simulation results. Finally, its innovative fabrication process and issues are reported and discussed.

Nano-Bio Interactions of Extracellular Vesicles with Gold Nanoislands for Early Cancer Diagnosis

Extracellular vesicles or exosomes are membrane encapsulated biological nanometric particles secreted virtually by all types of cells throughout the animal kingdom. They carry a cargo of active molecules to proximal and distal cells of the body as mechanism of physiological communication, to maintain natural homeostasis as well as pathological responses. Exosomes carry a tremendous potential for liquid biopsy and therapeutic applications. Thus, there is a global demand for simple and robust exosome isolation methods amenable to point-of-care diagnosis and quality control of therapeutic exosome manufacturing. This can be achieved by molecular profiling of the exosomes for use with specific sets of molecular-markers for diagnosis and quality control. Liquid biopsy is undoubtedly the most promising diagnosis process to advance "personalized medicine." Currently, liquid biopsy is based on circulating cancer cells, cell free-DNA, or exosomes. Exosomes potentially provide promise for early-stage diagnostic possibility; in order to facilitate superior diagnosis and isolation of exosomes, a novel platform is developed to detect and capture them, based on localized surface plasmon resonance (LSPR) of gold nanoislands, through strong affinity between exosomes and peptide called Venceremin or Vn96. Physical modeling, based on the characteristics of the gold nanoislands and the bioentities involved in the sensing, is also developed to determine the detection capability of the platform, which is optimized experimentally at each stage. Preliminary results and modeling present a relationship between the plasmonic shift and the concentration of exosomes and, essentially, indicate possibilities for label-free early diagnosis.

Hybrid piezoresistive-optical tactile sensor for simultaneous measurement of tissue stiffness and detection of tissue discontinuity in robot-assisted minimally invasive surgery

To compensate for the lack of touch during minimally invasive and robotic surgeries, tactile sensors are integrated with surgical instruments. Surgical tools with tactile sensors have been used mainly for distinguishing among different tissues and detecting malignant tissues or tumors. Studies have revealed that malignant tissue is most likely stiffer than normal. This would lead to the formation of a sharp discontinuity in tissue mechanical properties. A hybrid piezoresistive-optical-fiber sensor is proposed. This sensor is investigated for its capabilities in tissue distinction and detection of a sharp discontinuity. The dynamic interaction of the sensor and tissue is studied using finite element method. The tissue is modeled as a two-term Mooney–Rivlin hyperelastic material. For experimental verification, the sensor was microfabricated and tested under the same conditions as of the simulations. The simulation and experimental results are in a fair agreement. The sensor exhibits an acceptable linearity, repeatability, and sensitivity in characterizing the stiffness of different tissue phantoms. Also, it is capable of locating the position of a sharp discontinuity in the tissue. Due to the simplicity of its sensing principle, the proposed hybrid sensor could also be used for industrial applications.

A brief review on microfluidic platforms for hormones detection

Lab-on-chip technology is attracting great interest due to its potential as miniaturized devices that can automate and integrate many sample-handling steps, minimize consumption of reagent and samples, have short processing time and enable multiplexed analysis. Microfluidic devices have demonstrated their potential for a broad range of applications in life sciences, including point-of-care diagnostics and personalized medicine, based on the routine diagnosis of levels of hormones, cancer markers, and various metabolic products in blood, serum, etc. Microfluidics offers an adaptable platform that can facilitate cell culture as well as monitor their activity and control the cellular environment. Signaling molecules released from cells such as neurotransmitters and hormones are important in assessing the health of cells and the effect of drugs on their functions. In this review, we provide an insight into the state-of-art applications of microfluidics for monitoring of hormones released by cells. In our works, we have demonstrated efficient detection methods for bovine growth hormones using nano and microphotonics integrated microfluidics devices. The bovine growth hormone can be used as a growth promoter in dairy farming to enhance the milk and meat production. In the recent years, a few attempts have been reported on developing very sensitive, fast and low-cost methods of detection of bovine growth hormone using micro devices. This paper reviews the current state-of-art of detection and analysis of hormone using integrated optical micro and nanofluidics systems. In addition, the paper also focuses on various lab-on-a-chip technologies reported recently, and their benefits for screening growth hormones in milk.

Technical note: A portable on-chip assay system for absorbance and plasmonic detection of protein hormone in milk

This paper reports a portable device and method to extract and detect protein hormone in milk samples. Recombinant protein hormone spiked into milk samples was extracted by solid-phase extraction, and detection was carried out using the plasmonic property of gold nanoislands deposited on a glass substrate. Trace levels of hormone spiked in milk were analyzed by their optical absorbance property using a microfluidic chip. We built a portable assay system using disposable lab-on-chip devices. The proposed method is able to detect spiked recombinant protein hormone in milk at concentrations as low as 5ng/mL.

Dynamic, high precision targeting of growth modulating agents is able to trigger pollen tube growth reorientation

The pollen tube is the most rapidly growing cell in the plant kingdom and has the function to deliver the sperm cells for fertilization. The growing tip region of the cell behaves in a chemotropic manner to respond to the guidance cues emitted by the pistil and the female gametophyte, but how it perceives and responds to these directional triggers is virtually unknown. Quantitative assessment of chemotropic behavior can greatly be enhanced by the administration of pharmacological or other biologically active agents at subcellular precision, which is a technical challenge when the target area moves as it grows. We developed a laminar flow based microfluidic device that allows for continuous administration of two different solutions with a movable interface that permits the dynamic targeting of the growing pollen tube apex over prolonged periods of time. Asymmetric administration of calcium revealed that rather than following the highest calcium concentration as would be expected with simple chemotropic behavior, the pollen tube of Camellia targets an optimal concentration suggesting the presence of two superimposed mechanisms. Subcellular application of pectin methyl esterase (PME), an enzyme that modifies the growth behavior by rigidifying the pollen tube cell wall, caused the tube to turn away from the agent - providing important evidence for a previously proposed conceptual model of the growth mechanism.

Lab-on-a-chip for studying growing pollen tubes

A major limitation in the study of pollen tube growth has been the difficulty in providing an in vitro testing microenvironment that physically resembles the in vivo conditions. Here we describe the development of a lab-on-a-chip (LOC) for the manipulation and experimental testing of individual pollen tubes. The design was specifically tailored to pollen tubes from Camellia japonica, but it can be easily adapted for any other species. The platform is fabricated from polydimethylsiloxane (PDMS) using a silicon/SU-8 mold and makes use of microfluidics to distribute pollen grains to serially arranged microchannels. The tubes are guided into these channels where they can be tested individually. The microfluidic platform allows for specific testing of a variety of growth behavioral features as demonstrated with a simple mechanical obstacle test, and it permits the straightforward integration of further single-cell test assays.

Applications of microfluidics for studying growth mechanisms of tip growing pollen tubes

Pollen tube, the fastest tip growing plant cell, plays essential role in life cycle of flowering plants. It is extremely sensitive to external cues and this makes it as a suitable cellular model for characterizing the cell response to the influence of various signals involved in cellular growth metabolism. For in-vitro study of pollen tube growth, it is essential to provide an environment the mimics the internal microenvironment of pollen tube in flower. In this context, microfluidic platforms take advantage of miniaturization for handling small volume of liquids, providing a closed environment for in-vitro single cell analysis, and characterization of cell response to external cues. These platforms have shown their ability for high-throughput cellular analysis with increased accuracy of experiments, and reduced cost and experimental times. Here, we review the recent applications of microfluidic devices for investigating several aspects of biology of pollen tube elongation.

Rapid microwave-induced synthesis of gold-polydimethylsiloxane nanocomposites for biosensing of proteins

In this paper a novel in-situ microwave-induced synthesis of the gold-polydimethylsiloxane nanocomposite is presented. Microwave-induced synthesis has the advantages of a very short reaction time, small particle size and narrow size distribution of the particles. The ethanol solution of gold chloroauric acid is used as the precursor solution. The mechanism of formation and growth of nanoparticles are discussed in detail. UV/Vis spectroscopy and SEM imaging were used to characterize the optical properties and the size distribution of the particles. To improve the sensing properties of the nanocomposite, an annealing process were used. The results show that the annealed samples have the high sensitivity of 102 nm/RIU toward the surrounding medium which makes the nanocomposite suitable for biosensing applications. In addition, the elasticity of the platform in the presence of gold nanoparticles was found to be enhanced up to 20%. Finally, the immunosensing of the bovine growth hormone was performed by using the localized surface plasmon resonance (LSPR) band of gold nanoparticles. The results demonstrate suitability of the nanocomposite platform for biosensing applications. The results are highly relevant for microfluidic-based biosensors.

Quantification of the Young's modulus of the primary plant cell wall using Bending-Lab-On-Chip (BLOC)

Biomechanical and mathematical modeling of plant developmental processes requires quantitative information about the structural and mechanical properties of living cells, tissues and cellular components. A crucial mechanical property of plant cells is the mechanical stiffness or Young's modulus of its cell wall. Measuring this property in situ at single cell wall level is technically challenging. Here, a bending test is implemented in a chip, called Bending-Lab-On-a-Chip (BLOC), to quantify this biomechanical property for a widely investigated cellular model system, the pollen tube. Pollen along with culture medium is introduced into a microfluidic chip and the growing pollen tube is exposed to a bending force created through fluid loading. The flexural rigidity of the pollen tube and the Young's modulus of the cell wall are estimated through finite element modeling of the observed fluid-structure interaction. An average value of 350 MPa was experimentally estimated for the Young's modulus in longitudinal direction of the cell wall of Camellia pollen tubes. This value is in agreement with the result of an independent method based on cellular shrinkage after plasmolysis and with the mechanical properties of in vitro reconstituted cellulose-callose material.

Quantification of cellular penetrative forces using lab-on-a-chip technology and finite element modeling

Tip-growing cells have the unique property of invading living tissues and abiotic growth matrices. To do so, they exert significant penetrative forces. In plant and fungal cells, these forces are generated by the hydrostatic turgor pressure. Using the TipChip, a microfluidic lab-on-a-chip device developed for tip-growing cells, we tested the ability to exert penetrative forces generated in pollen tubes, the fastest-growing plant cells. The tubes were guided to grow through microscopic gaps made of elastic polydimethylsiloxane material. Based on the deformation of the gaps, the force exerted by the elongating tubes to permit passage was determined using finite element methods. The data revealed that increasing mechanical impedance was met by the pollen tubes through modulation of the cell wall compliance and, thus, a change in the force acting on the obstacle. Tubes that successfully passed a narrow gap frequently burst, raising questions about the sperm discharge mechanism in the flowering plants.

Detection of recombinant growth hormone by evanescent cascaded waveguide coupler on silica-on-silicon

An evanescent wave based biosensor is developed on the silica-on-silicon (SOS) with a cascaded waveguide coupler for the detection of recombinant growth hormone. So far, U -bends and tapered waveguides are demonstrated for increasing the penetration depth and enhancing sensitivity of the evanescent wave sensor. In this work, a monolithically integrated sensor platform containing a cascaded waveguide coupler with optical power splitters and combiners designed with S -bends and tapper waveguides is demonstrated for an enhanced detection of recombinant growth hormone. In the cascaded waveguide coupler, a large surface area to bind the antibody with increased penetration depth of evanescent wave to excite the tagged-rbST is obtained by splitting the waveguide into multiple paths using Y splitters designed with s -bends and subsequently combining them back to a single waveguide through tapered waveguide and combiners. Hence a highly sensitive fluoroimmunoassay sensor is realized. Using the 2D FDTD (Finite-difference time-domain method) simulation of waveguide with a point source in Rsoft FullWAVE, the fluorescence coupling efficiency of straight and bend section of waveguide is analyzed. The sensor is demonstrated for the detection of fluorescently-tagged recombinant growth hormone with the detection limit as low as 25 ng/ml.

TipChip: a modular, MEMS-based platform for experimentation and phenotyping of tip-growing cells

Large-scale phenotyping of tip-growing cells such as pollen tubes has hitherto been limited to very crude parameters such as germination percentage and velocity of growth. To enable efficient and high-throughput execution of more sophisticated assays, an experimental platform, the TipChip, was developed based on microfluidic and microelectromechanical systems (MEMS) technology. The device allows positioning of pollen grains or fungal spores at the entrances of serially arranged microchannels equipped with microscopic experimental set-ups. The tip-growing cells (pollen tubes, filamentous yeast or fungal hyphae) may be exposed to chemical gradients, microstructural features, integrated biosensors or directional triggers within the modular microchannels. The device is compatible with Nomarski optics and fluorescence microscopy. Using this platform, we were able to answer several outstanding questions on pollen tube growth. We established that, unlike root hairs and fungal hyphae, pollen tubes do not have a directional memory. Furthermore, pollen tubes were found to be able to elongate in air, raising the question of how and where water is taken up by the cell. The platform opens new avenues for more efficient experimentation and large-scale phenotyping of tip-growing cells under precisely controlled, reproducible conditions.

High Sensitive Force Sensing Based on the Optical Fiber Coupling Loss

In the present paper, an innovative miniaturized optical force sensor is introduced for use in medical devices such as minimally invasive robotic-surgery instruments. The sensing principle of the sensor relies on light transmission in optical fibers. Although the sensor is designed for use in surgical systems, it can be used in various other applications due to its novel features. The novelty of the sensor lies in offering four features in a single miniaturized package using a simple optical-based sensing principle. These four features are the high accuracy/resolution, the magnetic resonance compatibility, the electrical passivity, and the absence of drift in the measurement of continuous static force. The proposed sensor was micromachined using microsystems technology and tested. The sensor measures 18 mm, 4 mm, and 1 mm in length, width, and thickness, respectively. The sensor was calibrated and its performance under both static and dynamic loading conditions was investigated. The experimental test results demonstrate a 0.00–2.00 N force range with an rms error of approximately 2% of the force range. Its resolution is 0.02 N. The characteristics of the sensor such as its size, its measurement range, and its sensitivity are also easily tunable.

Integration of gold nanoparticles in PDMS microfluidics for lab-on-a-chip plasmonic biosensing of growth hormones

Gold nanoparticles were synthesized in a poly(dimethylsiloxane) (PDMS) microfluidic chip by using an in-situ method, on the basis of reductive properties of the cross-linking agent of PDMS. The proposed integrated device was further used as a sensitive and low-cost LSPR-based biosensor for the detection of polypeptides. Synthesis of nanoparticles in the microfluidic environment resulted in improvement of size distribution with only 8% variation, compared with the macro-environment that yields about 67% variation in size. The chemical kinetics of the in-situ reaction in the microfluidic environment was studied in detail and compared with the reaction carried out at the macro-scale. The effect of temperature and gold precursor concentration on the kinetics of the reaction was investigated and the apparent activation energy was estimated to be Ea*=30 kJ/mol. The sensitivity test revealed that the proposed sensor has a high sensitivity of 74 nm/RIU to the surrounding medium. The sensing of bovine growth hormone also known as bovine somatotropin (bST) shows that the proposed biosensor can reach a detection limit of as low as 3.7 ng/ml (185 pM). The results demonstrate the successful integration of microfluidics and nanoparticles which provides a potential alternative for protein detection in clinical diagnostics.