Phase shift ring down measurement approach (PS-CRDS) is used to develop a real time biosensor which can simultaneously track the quality factor Q and the resonant wavelength λ_r of microcavities as a function of the biodetection event. We have developed a mathematical model to predict the binding event with high accuracy by utilizing the information from these two physical parameters (Q and λ_r). Experiments are also conducted to validate the model. Hence, PS-CRDS biosensor in conjunction with the estimation model, will pave the way for highly sensitive measurements of biological entities/processes ranging from micron to nano scale.

We integrated 441 photonic crystal nanolasers and applied it to label-free live cell imaging. Since the mechanical strength of the nanolaser array was improved by bonding on a glass substrate, the imaging area was expanded from previous 25 × 25 μm² to 100 × 100 μm². We successfully acquired cell images, which should reflect the intracellular and/or the attachment conditions. By continuously mapping the wavelengths of all nanolasers, we successfully observed the time-dependent images displaying the cell behaviors. Reagents were injected to stimulate the cells, and the observation was continued until the cell reaction was saturated. The results show the reasonable behaviors against the reagents.

Noble metal nanoparticles supporting localized surface plasmon resonances (LSPR) have been extensively investigated for label free detection of various biological and chemical interactions. When compared to traditional propagating surface plasmon based sensors, LSPR sensors offer extensive wavelength tunability, greater electric field enhancement and sensing in reduced volumes. However, these sensors also suffer from a major disadvantage – LSPR sensors remain highly susceptible to interference because they respond to both solution refractive index changes and non-specific binding as well as specific binding of the target analyte. These interactions can compromise the measurement of the target analyte in a complex unknown media and hence limit the applicability and impact of the sensor. Despite the extensive amount of work done in this field, there has been an absence of optical techniques that make these sensors immune to interfering effects. Recently, our group experimentally demonstrated a multi-mode LSPR sensor that exploits three resonances of a U-shaped gold nanostructure to differentiate the target interaction from bulk and surface interfering effects. In this paper, we provide a comprehensive description of the electric field profiles of the three resonances of the U-shaped nanostructure. We will also evaluate the sensitivities of the nanostructure to the various bulk and surface interactions using numerical simulations.

We studied up-conversion emission of triply doped (Ho,Tm,Yb):KLu(WO₄)₂ (KLuW) nanocrystals at the range of temperature 296-673 K at different excitation wavelengths. The intensity ratio between two emission lines was used for monitoring the temperature. Pumping Yb³+ at 980 nm provides a good response at relatively high temperatures, while pumping Tm³+ at 802 nm provides an excellent sensitivity in the biological range of temperatures., which make the material also attractive for biological temperature sensors.

In order to quantify the binding capacities of polymeric, biodegradable and biocompatible poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), conjugated with either R11 peptides or Folic Acid, the strength by detach from prostate cancer cells (PCCs) was measured via optical tweezers based measurements. Specific nanoparticle drug delivery eliminates the previously used diffuse, full-body application of potent cancer drugs by localizing drug delivery to malignant cells. Precise monitoring of NP position in the trap near the PCC membrane using a fluorescence imaging based method enabled calibration of the trap stiffness and subsequent force measurements. By defining the force with which the many diverse conjugates and coatings of different types of NPs bind the vast array of cancer cell types, chemotherapeutic drugs can be delivered in a specific manner with the optimal particle and corresponding conjugates. Further, and most significantly, the rupture force measurements will reveal whether or not targeted nanoparticles can overcome the force of blood attempting to pull the particle from designated cells. Our preliminary study revealed that the binding between PLGA-NPs and prostate cancer cells is enhanced by coating with folic acid or R11 peptides. These conjugates increase the force required to detach the particle thus allowing particles to overcome drag force of the blood in prostate capillary systems.

We demonstrate the use of colloidal quantum dots (QDs) as refractive index signal amplifiers for the dual-mode, optical detection of biotin in streptavidin-functionalized porous silicon (PSi) biosensors. The nanoporous silicon host matrix was first analyzed to determine the relationship between different formation conditions, the resulting pore size distributions, and the efficiency with which different sized target molecules infiltrate and bind to the pore walls. Non-specific detection of glutathione conjugated with QDs was then demonstrated using PSi films with different average pore diameters. The specific detection of small biotin molecules was confirmed when the QD-biotin conjugates resulted in a six-fold increase in the reflectance fringe shift and a distinctive fluorescence spectrum upon exposure to an optimized, streptavidin-functionalized PSi sensor. A biotin detection limit of 0.5 fg/mm² is achievable.

In this report, we prepared a porous Si nanoparticle with a pore morphology that facilitates the proximal loading and alignment of magnetite nanoparticles. We characterized the composite materials using superconducting quantum interference device magnetometry, dynamic light scattering, transmission electron microscopy, and MRI. The in vitro cytotoxicity of the composite materials was tested using cell viability assays on human liver cancer cells and rat hepatocytes. An in vivo analysis using a hepatocellular carcinoma (HCC) Sprague Dawley rat model was used to determine the biodistribution properties of the material, while naïve Sprague Dawley rats were used to determine the pharmocokinetic properties of the nanomaterials. The composite material reported here demonstrates an injectable nanomaterial that exploits the dipolar coupling of superparamagnetic nanoparticles trapped within a secondary inorganic matrix to yield significantly enhanced MRI contrast. This preparation successfully avoids agglomeration issues that plague larger ferromagnetic systems. A Fe₃O₄:pSi composite formulation consisting of 25% by mass Fe₃O₄ yields an maximal T2* value of 556 mM Fe⁻¹ s⁻¹. No cellular (HepG2 or rat hepatocyte cells) or in vivo (rat) toxicity was observed with the formulation, which degrades and is eliminated after 4–8 h in vivo. The ability to tailor the magnetic properties of such materials may be useful for in vivo imaging, magnetic hyperthermia, or drug-delivery applications.

We report on application of on-chip referencing to improve the limit-of-detection (LOD) in compact silicon nitride (SiN) microring arrays. Microring resonators, fabricated by e-beam lithography and fluorine-based etching, are designed for visible wavelengths (656nm) and have a footprint of 20 x 20 μm. GM1 ganglioside is used as the specific ligand for recognition of Cholera Toxin Subunit B (CTB), with Ricinus Communis Agglutinin I (RCA I) as a negative control. Using micro-cantilever based printing less than 10 pL of glycan solution is consumed per microring. Real-time data on analyte binding is extracted from the shifts in resonance wavelengths of the microrings.

Nanoparticle-based delivery of drugs has gained a lot of prominence recently but the main problem hampering efficient delivery of payload is the clearing or degradation of nanoparticles by endosomes. Various strategies have been used to overcome this issue and one such effective solution is Photochemical Internalization (PCI). This technique involves the activation of certain photosensitizing compounds by light, which accumulate specifically in the membranes of endocytic vesicles. The activated photosensitizers induce the formation of reactive oxygen species which in turn induces localized disruption of endosomal membranes. But the drawback of this technique is that it needs blue light for activation and hence confined to be used only in in-vitro systems due to the poor tissue penetration of blue light. Here, we report the use of Upconversion nanoparticles (UCNs) as a transducer for activation of the photosensitizer, TPPS 2a. NIR light has good tissue penetrating ability and thus enables PCI in greater depths. Highly monodisperse, uniformly-sized, sub-100 nm, biocompatible upconversion nanoparticles were synthesized with a mesoporous silica coating. These UCNs activated TPPS 2a efficiently in solution and in cells. Paclitaxel, an anti-cancer drug was used as a model drug and was loaded into the mesoporous silica coating. B16F0 cells transfected with drug-loaded UCNs and irradiated with NIR showed significantly higher nanoparticle uptake and in turn higher cell death caused by the delivered drug. This technique can be used to enhance the delivery of any therapeutic molecule and thus increase the therapeutic efficiency considerably.

We study super-resolution capability of liquid-immersed high refractive index (n~1.9–2.1) barium titanate glass microspheres with diameters from several microns up to hundreds of microns. Imaging is provided in a conventional upright microscope with the spheres placed in a contact position with various semiconductor and metallic nanostructures. Using a commercial Blu-ray disk, we demonstrate an ability to discern 100 nm feature sizes which cannot be resolved by conventional microscopy. Using silver nanowires with diameter about 100 nm, we demonstrate ~1.7 times improvement in spatial resolution compared to conventional diffraction-limited far field microscopy. Using two-dimensional nanoplasmonic arrays, we demonstrate high resolution imaging by using objectives with surprisingly small numerical apertures. The last property is attractive for high-resolution imaging at long working distances. This imaging technique can be used in biomedical microscopy, microfluidics, and nanophotonics applications.

Nanoparticles doped with rare earth ions for biomedical imaging and infrared photodynamic therapy (IRPDT) have been synthesized, characterized, and compared. Specifically, these nanoparticles utilize two primary modalities: near infrared excitation and emission for imaging, and near infrared upconversion for photodynamic therapy. These nanoparticles are optimized for both their infrared emission and upconversion energy transfer to a photoactive agent conjugated to the surface. Finally, these nanoparticles are tested for toxicity, imaged in cells using the near infrared emission pathway, and used for selective killing of cells through the upconversion driven IRPDT.

Collagen is the major fibrous protein in the extracellular matrix and consists a significant component of skin, bone, cartilage and tendon. Due to its unique properties, it has been widely used as scaffold or culture substrate for tissue regeneration or/and cell-substrate interaction studies. The ultraviolet light-collagen interaction investigations are crucial for the improvement of many applications such as that of the UV irradiation in the field of biomaterials, as sterilizing and photo-cross-linking method. The aim of this paper was to investigate the mechanisms of UV-collagen interactions by developing a collagen-based, well characterized, surface with controlled topography of collagen thin films in the nanoscale range. The methodology was to quantify the collagen surface modification induced on ultraviolet radiation and correlate it with changes induced in cells. Surface nanoscale characterization was performed by Atomic Force Microscopy (AFM) which is a powerful tool and offers quantitative and qualitative information with a non-destructive manner. In order to investigate cells behavior, the irradiated films were used for in vitro cultivation of human skin fibroblasts and the cells morphology, migration and alignment were assessed with fluorescence microscopy imaging and image processing methods. The clarification of the effects of UV light on collagen thin films and the way of cells behavior to the different modifications that UV induced to the collagen-based surfaces will contribute to the better understanding of cell-matrix interactions in the nanoscale and will assist the appropriate use of UV light for developing biomaterials.

Confocal Raman Microscopy, a non-invasive, label free imaging technique is used to study apoptosis in living MCF-7 cells. The images are based on Raman spectra of cells components. K-mean clustering was used to determine mitochondria position in cells and cytochrome c distribution inside the cells was based on correlation analysis. Cell apoptosis is defined as cytochrome c diffusion in cytoplasm. Co-localization of cytochrome c is found within mitochondria after three hours of incubation with 10 μM paclitaxel. Our results demonstrate that the presence of paclitaxel at this concentration in the culture media for 3 hours does not induce apoptosis of MCF7 cells via a caspase independent pathway.

Biosensors which can selectively detect a very small amount of biomarker protein in human blood are desired toward early diagnoses of severe diseases. However, no methods simultaneously satisfy the requirements such as high sensitivity, high selectivity, simple detection, and immediacy. We succeeded in detecting ultra-low-concentration streptavidin (SA) even in a highly impure sample using nanoslot photonic crystal (PC) nanolasers. This nanolaser consists of GaInAsP semiconductor slab with a periodic airhole array. Since the total device area is no larger than 20 × 20 μm², highthroughput fabrication is possible even using e-beam lithography. Moreover, it is easy to operate by photopumping through free-space optics. Since the evanescent wave of the laser mode penetrates from the PC slab, the laser wavelength changes sensitively to the environmental index. In the sensing experiment, we first functionalized the devices with biotin, and then measured the wavelength in ultrapure water before and after immersing in the solutions with various concentrations of SA. As a result, we evaluated that the detection limit of SA is 16 zM. In another experiment, we put 1 μM BSA into the solution as a contaminant, and repeated the same measurement. We detected 100 zM SA even in the impure solution only when biotin is functionalized in advance, meaning a selectivity ratio (BSA / SA) of 10¹³. Thus this device achieves unprecedentedly high sensitivity and selectivity in addition to the simple fabrication and fast sensing. It is very promising as a point of care device for medical diagnoses.

In this paper we investigated the Paracoccidoides brasiliensis fungus nanosensor by simulations of simple strand DNA grafting on gold nanoparticle. In order to improve the knowledge of nanoparticle environment, the addiction of salt solution was studied at the models proposed by us. Nanoparticle and DNA are represented by economic models validated by us in this paper. In addition, the DNA grafting and salt influences are evaluated by adsorption and bond energies calculations. This theoretical evaluation gives support to experimental diagnostics techniques of diseases.

Tumor detection is a significant health issue, but it is still a limit to identify cancer cells during tumor resection by using traditional methods such as fluorescence. In this study, zinc oxide (ZnO) nanorods bonded to antibodies was investigated as nanoprobes for sensing cancer cells. The result shows that antibodies toward epidermal growth factor receptor (EGFR) can be connected to ZnO nanorods and EGFR receptors of squamous cell carcinoma (SCC). The cancer cells can be recognized via the observation of purple light emission from these probes by using naked eye or an optical microscope. By contrast, the HS68 cells with less EGFR expression had no purple light emission as the probes were washed off. Besides, from the photoluminescent spectra, the intensity ratio between the purple light (from ZnO nanorods) and green band (from the autofluorescence of cells) is much higher in SCC than in HS68 cells, which suggest that the cancer cells can be detected by comparing the peak intensity ratio. The probes have the potential clinical application for real-time tumor detection, and the cancer cells can be excised more precisely with the help of purple light emission.

In this work we propose the use of experimental and theoretical reflectance anisotropy spectra (RAS) as a new tool to identify structural and dynamical aspects of the bilipid membrane and its various constituent molecules. The role of geometric details at the atomic level and macroscopic quantities, such as the membrane curvature and tilt for the different gel phases, in the theoretical RAS spectra (using Kohn-Sham density functional theory (KS-DFT)) are presented. Then the results are compared to the experimentally measured spectra taken from other techniques.

By exploiting near field optical forces, the Molecular NanoTweezer can trap the smallest nanoparticles yet reported inluding individual proteins and quantum dots. This breakthrough is being commercialized and will produce the first system to allow for direct optical manipulation of biologically relevant nanoparticles. This breakthrough is being commercialized and will produce the first system to allow direct optical manipulation of biological nanoparticles. The Molecular NanoTweezer overcomes the lower size limit imposed by diffraction (the limit of traditional optical tweezers) by using waveguides and optical resonators patterned on silicon chips that produce near field optical forces. In this talk, we will discuss current and future applications of this technology, including surface-tether-free immunoassays. We will finalize our talk by briefly overviewing the commercialization efforts.

We investigated the difference in electrically guided acto-myosin motility on two surfaces. Rabbit skeletal muscle heavy meromyosin (HMM) was absorbed onto surfaces coated with Nitrocellulose (NC) and Poly(butyl methacrylate) (PBMA). A modified in vitro motility assay with sealed chambers for the insertion of electrodes allowed an electrical field to be applied across the flow cell. On all surfaces a small increase in velocity and general guidance of the actin filaments towards the positive electrode is seen at field strengths in the range of ~3000 – 4000Vm^-1. A large increase in velocity was observed at ~5000Vm^-1 and a significant change in the velocity of the actin filaments present in field strengths higher than this. NC supported the highest percentage of motile filaments and at a field of 8000Vm^-1 reached ~66%. PBMA however supported the least percentage of motile filaments and irregular motility was observed even at higher fields where guidance was expected to be strong. The change in velocity in the range of fields tested varied significantly on the surfaces with NC displaying a 46% increase from 0 to 8000Vm^-1 whereas on PBMA this value was just 37%.

This PDF file contains the front matter associated with SPIE Proceedings Volume 8594, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.