This PDF file contains the front matter associated with SPIE Proceedings Volume 10508, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Neuroinflammation is a dynamic immune phenomenon that changes in severity with time after neurotrauma and has a profound impact on neuroregeneration, tissue healing and neuropathic pain, which is a common consequence of peripheral nerve injury (PNI). Macrophages are key cellular mediators of neuroinflammation. Macrophage-targeted nanotherapies, such as complex (perfluorocarbon/hydrocarbon) multimodal nanoemulsions (NEs) provide highly specific imaging signatures of neuroinflammation and hence indirect surrogate metrics of regeneration. We present a novel strategy where these NEs incorporating multiple imaging modalities and biosensors are delivered locally to directly target key cellular players of neuroregeneration. Two representative formulations of a nanotheranostic platform for local delivery of cell targeted NEs are presented: 1) A dual (macrophage and neuronal) targeted nanoparticle laden hydrogel for synergistic modulation of neuroinflammation and analgesia following PNI; and 2) neurotherapeutic loaded nanoparticles with extended release profile for sustained support of neuroregeneration. Each platform is capable of dual imaging payloads (NIRF, MRI and/or PET) and/or cell specific targeting moieties for controlled drug release. In vitro and pilot in vivo results will be presented. Theranostic nanosystem based platforms offer a unique opportunity to sequentially monitor cellular and molecular events at the site of neuronal injury, enabling dynamic, in-vivo mechanistic insights rather than static, ex-vivo histopathologic evaluation. Given their targeted capabilities, these platforms can help achieve personalized treatments that are customized and optimized for patients with PNI.

Quantitative and noninvasive measurement of protease activities has remained an imaging challenge in deep tissues such as the lungs. Here, we designed a dual-radiolabeled probe for reporting the activities of proteases such as matrix metalloproteinases (MMPs) with multispectral single photon emission computed tomography (SPECT) imaging. A gold nanoparticle (NP) was radiolabeled with ¹²⁵I and ¹¹¹In and functionalized with an MMP9-cleavable peptide to form a multispectral SPECT imaging contrast agent. In another design, incorporation of ¹⁹⁹Au radionuclide into the metal crystal structure of gold NPs provided a superior and stable reference signal in lungs, and ¹¹¹In was linked to the NP surface via a protease-cleavable substrate, which can serve as an enzyme activity reporter. This work reveals strategies to correlate protease activities with diverse pathologies in a tissue-depth independent manner.

Demands in flow cytometry for increased multiplexing (for detection of multiple antigens) and brightness (for detection of rare entities) require new fluorophores (i.e., “colors”) with spectrally distinct fluorescence outside the relatively congested visible spectral region. Flow cytometry fluorophores typically must function in aqueous solution upon bioconjugation and ideally should exhibit a host of photophysical features: (i) strong absorption, (ii) sizable Stokes shift, (iii) modest if not strong fluorescence, and (iv) narrow fluorescence band. Tandem dyes have long been pursued to achieve a large effective Stokes shift, increased brightness, and better control over the excitation and emission wavelengths. Here, the attractive photophysical features of chlorophylls and bacteriochlorophylls – Nature’s chosen photoactive pigments for photosynthesis – are described with regards to use in flow cytometry. A chlorophyll (or bacteriochlorophyll) constitutes an intrinsic tandem dye given the red (or near-infrared) fluorescence upon excitation in the higher energy ultraviolet (UV) or visible absorption bands (due to rapid internal conversion to the lowest energy state). Synthetic (bacterio)chlorins are available with strong absorption (near-UV molar absorption coefficient ε(λ_exc) ~10⁵ M^-1cm^-1), modest fluorescence quantum yield (Φf = 0.05–0.30), and narrow fluorescence band (10–25 nm) tunable from 600–900 nm depending on synthetic design. The “relative practical brightness” is given by intrinsic brightness [ε(λ_exc) x Φ_f] times η_f, the fraction of the fluorescence band that is captured by an emission filter in a multicolor experiment. The spectroscopic features of (bacterio)chlorins are evaluated quantitatively to illustrate practical brightness for this novel class of fluorophores in a prospective 8-color panel.

Cyclic arginine-glycine-aspartic acid (cRGD) peptides are well known to target α_νβ₃ integrin expressed on cancer cells and neovasculature. Conjugation of these peptides with dyes, drugs, antibodies and other biomolecules through covalent linkers provides a facile way to deliver these products to tumor cells for targeted cancer therapy and diagnosis. Click chemistry and acid-amine couplings are widely used conjugation strategies. However, the effects of different linkers and the distance between the cRGD and the conjugates on the binding of cRGD ligand with α_νβ₃ has been underexplored.

In this present study, we prepared cRGD-conjugates using different linkers and determined how they altered the tumor targeting efficiency in vitro and in vivo. The results demonstrate that different linkers significantly altered the pharmacokinetics of the cRGD conjugates and the tumor uptake kinetics. Unlike large antibodies, this preliminary finding shows that linkers used to attach drugs and fluorescent molecular probes to small peptides play a major role in the accuracy of tumor targeting and treatment outcomes. As a result, considerable attention should be paid to the nature of linkers used in the design of molecular probes and targeted therapeutics.

Fluorescence spectroscopy has become a widely accepted method in many applications in chemistry, biology, biochemistry and biophysics just to mention a few areas because of its practicality and sensitivity. Major trend for these applications during the recent years is the use of longer wavelength fluorophores and encapsulation of fluorophores by utilizing nanoparticles. Longer fluorescence wavelengths have several advantages such as lower background interference that is especially important in complex biological samples. While many different types of nanoparticles can be utilized for encapsulation of these dyes, silica nanoparticles have significant advantages in biological system. The synthesis of silica nanoparticles is relatively straightforward and covalent copolymerization of fluorescent dyes during the silica nanoparticle synthesis is a easily controllable process by using modified TEOS reactive analogues that are widely available. Adding layers on silica nanoparticles different chemical or sensor functionality can be added to the silica nanoparticle surface. The fluorescence intensity of a fluorescent silica nanoparticle can significantly be increased by enclosing larger number of dye molecules in silica nanoparticles. Dependent on the size of the silica nanoparticle 20-50 or more dye molecules can be included using this copolymerization process. For high dye concentrations in the silica nanoparticle self quenching can be significant but it can be minimized by synthesizing large Stokes’ shift dyes. Using NIR dyes excellent sensitivity can be achieved but one major disadvantage is that most biological fluorescence instruments are designed for shorter excitation wavelengths frequently matching the optical properties of fluorescein, a widely used fluorophore. One approach to make these new fluorescent silica nanoparticles more compatible with widely used optical wavelength windows is the development of fluorescent silica nanoparticles containing copolymerized dyes that are good candidates for fluorescence energy transfer. For example if the donor is fluorescein the excitation wavelength is compatible with most instruments on the market. Systems that contain two or more dyes can be used to achieve long fluorescence wavelengths. This presentation discusses the facile synthesis and practical applications of silica nanoparticles containing copolymerized multiple fluorophores that are suitable for fluorescence energy transfer. Optimization of these systems requires the evaluation of individual dye concentrations (donors, acceptors and intermediators), concentration ratios to achieve high fluorescence. During these studies copolymerized energy transfer fluorescence silica nanoparticles were evaluated for their stability, fluorescence intensity and utility. The surface properties of fluorescence silica nanoparticles were modified by adding hydrophobic or hydrophilic molecules on the surface to achieve biocompatibility. Biocompatibility was evaluated by hemolytic experiments. Typical applications of these particles are for immunochemistry, flow cytometry, CE, forensic applications, biomolecule characterizations, etc.

Atherosclerosis, a condition in which plaque accumulates on the inner wall of arteries, is often recognized as a precursor to cardiovascular diseases (CVDs), the most common causes of death in the US. Optical Coherence Tomography (OCT) is an intravascular optical diagnosis tool, which can be used to obtain high resolution morphological images of atherosclerotic plaque. However, atherosclerotic plaque components, such as macrophages, can be misclassified due to their signal similarities to fibrin accumulations, cholesterol crystals and microcalcifications. To overcome these challenges, we develop a biocompatible contrast agent to enhance molecular imaging of a Pump-Probe OCT (PPOCT) system. Methylene blue (MB) was encapsulated into poly lactic-co-glycolic acid (PLGA) particles by an emulsion/solvent evaporation technique. Fabrication parameters were controlled to synthesize particles with desired properties such as: size, encapsulation efficiency, degradation rate, and particle surface functionalization. The encapsulation of MB protects it from the enzymatic reduction to leuco-methylene blue (92.8 % protection), and reduces the singlet oxygen generation by the excited MB molecules by 78.3%. Likewise, the PLGA shells improve the OCT signal by enhancing the scattering of light. The surface of particles was modified with ligands that can target molecular biomarkers involved in atherosclerotic plaque formation such as vascular cell adhesion molecules (VCAM-1) and apoptotic macrophages. This modification is expected to enhance tissue selectivity, provides detailed information on the local biochemistry and yields visualization of pathological processes. PLGA-based contrast agents were tested in human postmortem artery sections to study particles permeability as a function of particle size and its molecular selectivity.

The large size of many near infrared (NIR) fluorescent nanoparticles prevents rapid extravasation from blood vessels and subsequent diffusion to tumors. This confines in vivo uptake to the peritumoral space and results in high liver retention. We developed a viscosity modulated approach to synthesize ultrasmall silver sulfide quantum dots (QDs) with distinct tunable light emission from visible to near-infrared in spectrum and a QD core diameter between less than 5 nm. Further functionalization of these Ag2S QDs with different type of molecules such as targeting peptides, retains monodisperse, relatively small water soluble QDs without loss of the functionality of the peptide’s high binding affinity to cancerous tumor. Fluorescence and electron microscopy showed that selective integrin-mediated internalization was observed only in cancer cells treated with the peptide-labeled QDs, demonstrating that the unlabeled hydrophilic nanoparticles exhibit characteristics of negatively charged fluorescent dye molecules, which typically do not internalize in cells. The biodistribution profiles of intravenously administered QDs in different mouse models of cancer reveal an exceptionally high tumor-to-liver uptake ratio, suggesting that the small sized QDs evaded conventional opsonization and subsequent high uptake in the liver and spleen. The seamless tunability of the QDs over a wide spectral range with only a small increase in size, as well as the ease of labeling the bright and non-cytotoxic QDs with biomolecules, provides a platform for multiplexing information, tracking the trafficking of single molecules in cells, and selectively targeting disease biomarkers in living organisms without premature QD opsonization in circulating blood.

Cadmium still represents a stigma for many research- and/or industrial applications. Some deleterious effects are attributed to Cadmium. In the present work, highly fluorescent Cadmium sulfide quantum dots are investigated by e.g. physical-chemical characterization. Most important however is their application as fluorescent probes for bio-imaging in living cells and tissues. This work presents their toxicological evaluation by means of in vivo studies. Bio-imaging experiments are performed without any pre-treatment. The toxicological studies performed, strongly indicate that the use of Cadmium based nanoparticles as fluorescent probes may be nonhazardous and not induce side effects for cells/tissues.

For the first time, the dependence of the bending force on the transverse displacement of atoms in the center of the composite material consisting of graphene and parallel oriented zigzag nanotubes was studied. Mathematical modeling of the action of the needle of the atomic force microscope was carried out using the single-layer armchair carbon nanotube. Armchair nanotubes are convenient for using them as a needle of an atomic force microscope, because their edges are not sharpened (unlike zigzag tubes). Consequently, armchair nanotubes will cause minimal damage upon contact with the investigation object. The geometric parameters of the composite was revealed under the action of the bending force of 6μN.

Porous carbon structures are the greatest interest, since they are actively used in various fields of science and technology. The aim of this work is the investigation of the mechanical strength of the porous carbon structures with a density of 1.4 g/cm³ with different pore sizes and different concentration of oxygen atoms. The investigation of the mechanical properties of porous carbon nanostructures was carried out on three models with different nanopore sizes (0.4-0.8 nm, 0.2 nm - 1.12 nm, 0.7-1.3 nm). The character of the change in the Young's modulus of porous nanostructures as a function of the location of oxygen atoms was established.

Investigation of conducting properties of ZnS quantum dot by acceding to them the gold atoms were presented. It was found that redistribution of electrons in the quantum dot change after the accession of the gold atoms. When adding gold atoms is observed the change in geometry of structure and the change in the redistribution of the electron density. Search equilibrium configuration of the molecule was carried out by the density of state method with basis b3lyp. The object of research is a symmetrical molecule ZnS.

In nowadays the nanoscale materials are actively used in medicine, based on the properties of adsorption. One of the main problems of this field of medicine is the increase in specific surface of sorbent. We proposed to use carbon composites consisting of an extended in its directions graphene sheet with attached to it by chemical bonds zigzag carbon nanotubes (CNT). This paper presents the results of a theoretical study of the mechanical properties of graphene based on the CNT zigzag depending on the geometric dimensions of the composite (length and diameter of CNTs).

The purpose of this work is to study the physical phenomena that arise during contact of DNA nucleotides with a graphene substrate, and the numerical evaluation of the electrically conductive properties of graphene-nucleotide complexes. As a graphene substrate we considered graphene nanoribbons of armchair and zigzag type. We investigated changes in the atomic structure of the graphene-nucleotide complexes. Such characteristics of the complexes as charge redistribution, electron transmission functions, electrical conductivity and current-voltage characteristic were calculated using Nonequilibrium Green’s function (NGF) matrices method. In order to calculate the electrical conductivity we constructed a model, where semi-infinite graphene sheets with the zigzag and armchair edges acted as electrodes, respectively. The search for the equilibrium configuration of graphenenucleotide complexe was carried out by the method of relaxation scanning of the multi-well potential of the nucleotide interaction energy with a carbon object. Analysis of the calculated resistances and current-voltage characteristic showed that the most suitable for biosensorics are graphene nanoribbons of the zigzag type.

At present, the liposomes are widely used as drug carriers in different areas of clinical medicine. One of them is the transport across the blood-brain barrier (BBB) into brain. This work is devoted to computational modeling of liposome transport across biomembrane. For this, we applied the MARTINI coarse-grained model. The liposome model is constructed from lipid (DPPC) and cholesterol (CHOL) molecules in a percentage ratio of 60/40. The diameter of the liposome is 28 nm. The equilibrium configuration of the liposome is achieved by minimizing its total energy. A series of numerical experiments was conducted in order to study the transport of the drug contained in the liposome across the cell membrane. All computer manipulations were carried out using software packages GROMACS and Kvazar at a temperature of 305-310 K. All the processes were simulated for 10-20 ns. The speed of the liposome ranged from 0.89 to 1.07 m/s. It should be noted that the selected speed range corresponds to the rate of human blood flow. Various cases of the angle of the incidence of the liposome on the membrane surface were also considered. Since the process of contact of the liposome with the membrane can be characterized as rolling in most cases, the angles were considered in the interval from 0 to 20 degrees. Based on the simulation results, we determined optimal pathways (from the point of view of energy) for liposome penetration across biomembrane.

Currently, the pathology of the cardiovascular system is an extremely urgent problem of fundamental and clinical medicine. These diseases are caused, mainly, by atherosclerotic changes in the wall of blood vessels. The predominant role in the development of atherosclerosis is attributed to the penetration of various kinds of lipoproteins into the arterial intima. In this paper, we in silico investigated the dynamics of the penetration of low density lipoprotein (LDL) through the intercellular gap using molecular modeling methods. The simulation was carried out in the GROMACS software package using a coarse-grained MARTINI model. During investigation we carried out the LDL self-assembly for the first time. The coarse-grained model of LDL was collected from the following molecules: POPC (phosphatidylcholine) - 630 molecules, LPC (lysophosphatidylcholine) - 80 molecules CHOL (cholesterol) - 600 molecules CHYO (cholesteryl oleate) - 1600 molecules TOG (glycerol trioleate) 180 Molecules. The coarse-grained model of the intercellular endothelial gap was based on a model of lipid bilayer consisting of DPPC phospholipids and cholesterol in a percentage ratio of 70% and 30%, respectively. Based on the obtained results, we can predict the mechanism of LDL diffusion. Lipoproteins can be deformed so as to pass through narrow gaps. Our investigations open the way for the research of the behavior dynamics of LDL moving with the blood flow rate when interacting with the intercellular gaps of the endothelial layer of the vessel inner wall.