Targeted multifunctional multimodal protein-shell microspheres as cancer imaging contrast agents

Chiroptically Active Multi-Modal Calcium Carbonate-Based Nanocomposites

The development of multimodal nano- and micro-structures has become an increasingly popular area of research in recent years. In particular, the combination of two or more desirable properties within a single structure opens multiple opportunities from biomedicine, sensing, and catalysis, to a variety of optical applications. Here, for the first time, we report the synthesis and characterization of multimodal chiroptically active CaCO3 nanocomposites. These composites have been prepared by a modified microemulsion method in the presence of an amino acid (cysteine). Following this, additional modalities have been introduced by loading the composites with luminescent nanoparticles or doping with Eu3+ ions. The luminescent composites have been produced by the incorporation of CuInZnS/ZnS or CdSe@ZnS/ZnS core/shell quantum dots, or via doping with trivalent europium. In this manner, we have produced chiroptically active composites with orange, green, and red luminescence. Overall, this work demonstrates the unique advantage and potential of our approach and new class of chiroptically active CaCO3 nanocomposites, which display tunable functionality to specific requirements via the incorporation of desired ions, nanoparticles, and chirality of the structure.

Update of ultrasound-assembling fabrication and biomedical applications for heterogeneous polymer composites

As a power-driving approach, ultrasound irradiation is very appealing to the preparation or modification of new materials. In the review, we overviewed the latest development of ultrasound-mediated effects or reactions in polymer composites, and demonstrated its unique and powerful aspects on the polymerization or aggregation. The review generalized the different categories of heterogeneous polymer composites by defining the constituents, and described the shapes, sizes and basic properties of various purpose-specific or site-specific products. Importantly, the review paid more attention to the main biomedicine applications of heterogeneous polymer composites, such as drug or bioactive substance entrapment, delivery, release, imaging, and therapy, and emphasized many advantages of ultrasound-assembling approaches and heterogeneous polymer composites in biology and medicine fields. In addition, the review also indicated the prospective challenges of heterogeneous polymer composites both in ultrasound-assembling designs and in biomedical applications.

Oral Cancer Screening by Artificial Intelligence-Oriented Interpretation of Optical Coherence Tomography Images

Early diagnosis of oral cancer is critical to improve the survival rate of patients. The current strategies for screening of patients for oral premalignant and malignant lesions unfortunately miss a significant number of involved patients. Optical coherence tomography (OCT) is an optical imaging modality that has been widely investigated in the field of oncology for identification of cancerous entities. Since the interpretation of OCT images requires professional training and OCT images contain information that cannot be inferred visually, artificial intelligence (AI) with trained algorithms has the ability to quantify visually undetectable variations, thus overcoming the barriers that have postponed the involvement of OCT in the process of screening of oral neoplastic lesions. This literature review aimed to highlight the features of precancerous and cancerous oral lesions on OCT images and specify how AI can assist in screening and diagnosis of such pathologies.

Nanoparticles-mediated Brain Imaging and Disease Prognosis by Conventional as well as Modern Modal Imaging Techniques: a Comparison

BACKGROUND

Multimodal imaging plays an important role in the diagnosis of brain disorders. Neurological disorders need to be diagnosed at an early stage for their effective treatment as later, it is very difficult to treat them. If possible, diagnosing at an early stage can be much helpful in curing the disease with less harm to the body. There is a need for advanced and multimodal imaging techniques for the same. This paper provides an overview of conventional as well as modern imaging techniques for brain diseases, specifically for tumor imaging. In this paper, different imaging modalities are discussed for tumor detection in the brain along with their advantages and disadvantages. Conjugation of two and more than two modalities provides more accurate information rather than a single modality. They can monitor and differentiate the cellular processes of normal and diseased condition with more clarity. The advent of molecular imaging, including reporter gene imaging, has opened the door of more advanced noninvasive detection of brain tumors. Due to specific optical properties, semiconducting polymer-based nanoparticles also play a pivotal role in imaging tumors.

OBJECTIVE

The objective of this paper is to review nanoparticles-mediated brain imaging and disease prognosis by conventional as well as modern modal imaging techniques.

CONCLUSION

We reviewed in detail various medical imaging techniques. This paper covers recent developments in detail and elaborates a possible research aspect for the readers in the field.

Common-path-based device for magnetomotive OCT noise reduction

Magnetomotive optical coherence tomography (MMOCT) is a promising imaging method for noninvasive three-dimensional tracking of magnetic nanoparticle (MNP) motions in target tissues or organs. The external B-field is the driving force that provides MMOCT contrast. However, B-field modulation also introduces modulation noise, thereby decreasing the quality of the MMOCT image. In this paper, a common-path-based device is designed for modulation noise reduction. The device is capable of adjusting interference distance, reference light intensity, and imaging position (X-Y translation). The sensitivity of the MMOCT is increased by ∼20 times with the new device. Using the proposed device, the distribution of MNPs injected in zebrafish was imaged.

Characterization of Magnetic Nanoparticle-Seeded Microspheres for Magnetomotive and Multimodal Imaging

Magnetic iron-oxide nanoparticles have been developed as contrast agents in magnetic resonance imaging (MRI) and as therapeutic agents in magnetic hyperthermia. They have also recently been demonstrated as contrast and elastography agents in magnetomotive optical coherence tomography and elastography (MM-OCT and MM-OCE, respectively). Protein-shell microspheres containing suspensions of these magnetic nanoparticles in lipid cores, and with functionalized outer shells for specific targeting, have also been demonstrated as efficient contrast agents for imaging modalities such as MM-OCT and MRI, and can be easily modified for other modalities such as ultrasound, fluorescence, and luminescence imaging. By leveraging the benefits of these various imaging modalities with the use of only a single agent, a magnetic microsphere, it becomes possible to use a widefield imaging method (such as MRI or small animal fluorescence imaging) to initially locate the agent, and then use MM-OCT to obtain dynamic contrast images with cellular level morphological resolution. In addition to multimodal contrast-enhanced imaging, these microspheres could serve as drug carriers for targeted delivery under image guidance. Although the preparation and surface modifications of protein microspheres containing iron oxide nanoparticles has been previously described and feasibility studies conducted, many questions regarding their production and properties remain. Since the use of multifunctional microspheres could have high clinical relevance, here we report a detailed characterization of their properties and behavior in different environments to highlight their versatility. The work presented here is an effort for the development and optimization of nanoparticle-based microspheres as multi-modal contrast agents that can bridge imaging modalities on different size scales, especially for their use in MM-OCT and MRI imaging.

Nanomedicines guided nanoimaging probes and nanotherapeutics for early detection of lung cancer and abolishing pulmonary metastasis: Critical appraisal of newer developments and challenges to clinical transition

Lung cancer (LC) is the second most prevalent type of cancer and primary cause of mortality among both men and women, worldwide. The most commonly employed diagnostic modalities for LC include chest X-ray (CXR), magnetic-resonance-imaging (MRI), computed tomography (CT-scan), and fused-positron-emitting-tomography-CT (PET-CT). Owing to several limitations associated with the use of conventional diagnostic tools such as radiation burden to the patient, misleading diagnosis ("missed lung cancer"), false staging and low sensitivity and resolution, contemporary diagnostic regimen needed to be employed for screening of LC. In recent decades, nanotechnology-guided interventions have been transpired as emerging nanoimaging probes for detection of LC at advanced stages, while producing signal amplification, better resolution for surface and deep tissue imaging, and enhanced translocation and biodistribution of imaging probes within the cancerous tissues. Besides enormous potential of nanoimaging probes, nanotechnology-based advancements have also been evidenced for superior efficacy for treatment of LC and abolishing pulmonary metastasis (PM). The success of nanotherapeutics is due to their ability to maximise translocation and biodistribution of anti-neoplastic agents into the tumor tissues, improve pharmacokinetic profiles of anti-metastatic agents, optimise target-specific drug delivery, and control release kinetics of encapsulated moieties in target tissues. This review aims to overview and critically discuss the superiority of nanoimaging probes and nanotherapeutics over conventional regimen for early detection of LC and abolishing PM. Current challenges to clinical transition of nanoimaging probes and therapeutic viability of nanotherapeutics for treatment for LC and PM have also been pondered.

Ultrasound Technology for Molecular Imaging: From Contrast Agents to Multimodal Imaging

Ultrasound (US) takes advantage of ultrasound contrast agents (UCAs) to further increase the sensitivity and specificity of monitoring at the cellular level, which has had a considerable effect on the modern molecular imaging field. Gas-filled microbubbles (MBs) as UCAs in the bloodstream generate resonant volumetric oscillations in response to rapid variations in acoustic pressure, which are related to both the acoustic parameters of applied ultrasound and the physicochemical properties of the contrast agents. Nanoscale UCAs have been developed and have attracted much attention due to their utility in detecting extravascular lesions. Ultrasound molecular assessment is achieved by binding disease-specific ligands to the surface of UCAs, which have been designed to target tissue biomarkers in the area of interest, such as blood vessels, inflammation, or thrombosis. Additionally, the development of multimodal imaging technology is conducive for integration of the advantages of various imaging techniques to acquire additional diagnostic information. In this review paper, the present status and the critical issues for developing ultrasound contrast agents and multimodal imaging applications are described. Conventional MB UCAs are first introduced, including their research material, diagnostic applications, and intrinsic limitations. Then, recent progress in developing targeted UCAs and phase-inversion contrast agents for diagnostic purposes is discussed. Finally, we review the present status and the critical issues for developing ultrasound-based multimodal imaging applications and summarize the existing challenges and future prospects.

Sonochemistry-Assembled Stimuli-Responsive Polymer Microcapsules for Drug Delivery

Stimuli-responsive polymer microcapsules (PMs) fabricated by the sonochemical method have emerged for developing useful drug delivery systems, and the latest developments are mainly focusing on the synthetic strategies and properties such as structure, size, stability, loading capacity, drug delivery, and release. There, the primary attribution of sonochemistry is to offer a simple and practical approach for the preparation of PMs. Structure, size, stability, and properties of PMs are designed mainly according to synthetic materials, implementation schemes, or specific demands. Numerous functionalities of PMs based on different stimuli are demonstrated: targeting motion in a magnetic field or adhering to the living cells with sensitive sites through molecular recognition, and stimuli-triggered release including enzymatic catalysis, chemical reaction as well as physical or mechanical process. The current review discusses the basic principles and mechanisms of stimuli effects, and describes the progress in the application such as targeted drug systems and controlled drug systems, and also gives an outlook on the future challenges and opportunities for drug delivery and theranostics.

Advances in Retinal Optical Imaging

Retinal imaging has undergone a revolution in the past 50 years to allow for better understanding of the eye in health and disease. Significant improvements have occurred both in hardware such as lasers and optics in addition to software image analysis. Optical imaging modalities include optical coherence tomography (OCT), OCT angiography (OCTA), photoacoustic microscopy (PAM), scanning laser ophthalmoscopy (SLO), adaptive optics (AO), fundus autofluorescence (FAF), and molecular imaging (MI). These imaging modalities have enabled improved visualization of retinal pathophysiology and have had a substantial impact on basic and translational medical research. These improvements in technology have translated into early disease detection, more accurate diagnosis, and improved management of numerous chorioretinal diseases. This article summarizes recent advances and applications of retinal optical imaging techniques, discusses current clinical challenges, and predicts future directions in retinal optical imaging.

On-demand one-step synthesis of small-sized fluorescent–magnetic bifunctional microparticles on a droplet-splitting chip

Generation of small-sized multifunctional microparticles: multifunctional microparticles were easily produced based on droplet splitting and photopolymerization in a single step.

Review of optical coherence tomography in oncology

The application of optical coherence tomography (OCT) in the field of oncology has been prospering over the past decade. OCT imaging has been used to image a broad spectrum of malignancies, including those arising in the breast, brain, bladder, the gastrointestinal, respiratory, and reproductive tracts, the skin, and oral cavity, among others. OCT imaging has initially been applied for guiding biopsies, for intraoperatively evaluating tumor margins and lymph nodes, and for the early detection of small lesions that would often not be visible on gross examination, tasks that align well with the clinical emphasis on early detection and intervention. Recently, OCT imaging has been explored for imaging tumor cells and their dynamics, and for the monitoring of tumor responses to treatments. This paper reviews the evolution of OCT technologies for the clinical application of OCT in surgical and noninvasive interventional oncology procedures and concludes with a discussion of the future directions for OCT technologies, with particular emphasis on their applications in oncology.

Targeted Soft Biodegradable Glycine/PEG/RGD-Modified Poly(methacrylic acid) Nanobubbles as Intelligent Theranostic Vehicles for Drug Delivery

The development of multifunctional ultrasound contrast agents has inspired considerable interest in the application of biomedical imaging and anticancer therapeutics. However, combining multiple components that can preferentially accumulate in tumors in a nanometer scale poses one of the major challenges in targeting drug delivery for theranostic application. Herein, reflux-precipitation polymerization, and N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide-meditated amidation reaction were introduced to effectively generate a new type of soft glycine/poly(ethylene glycol) (PEG)/RGD-modified poly(methacrylic acid) nanobubbles with a uniform morphology and desired particle size (less than 100 nm). Because of the enhanced biocompatibility resulting from the glycine modification, over 80% of the cells survived, even though the dosage of glycine-modified polymeric nanobubbles was up to 5 mg/mL. By loading doxorubicin as an anticancer drug and perfluorohexane as an ultrasound probe, the resulting glycine/PEG/RGD-modified nanobubbles showed remarkable cancer therapeutic efficacy and a high quality of ultrasonic imaging; thus, the ultrasonic signal exhibited a 1.47-fold enhancement at the tumor site after intravenous injection. By integrating diagnostic and therapeutic functions into a single nanobubble, the new type of theranostic nanobubbles offers a promising strategy to monitor the therapeutic effects, giving important insights into the ultrasound-traced and enhanced targeting drug delivery in biomedical applications.

Assessment of Molecular Acoustic Angiography for Combined Microvascular and Molecular Imaging in Preclinical Tumor Models

PURPOSE

The purposes of the present study is to evaluate a new ultrasound molecular imaging approach in its ability to image a preclinical tumor model and to investigate the capacity to visualize and quantify co-registered microvascular and molecular imaging volumes.

PROCEDURES

Molecular imaging using the new technique was compared with a conventional ultrasound molecular imaging technique (multi-pulse imaging) by varying the injected microbubble dose and scanning each animal using both techniques. Each of the 14 animals was randomly assigned one of three doses; bolus dose was varied, and the animals were imaged for three consecutive days so that each animal received every dose. A microvascular scan was also acquired for each animal by administering an infusion of nontargeted microbubbles. These scans were paired with co-registered molecular images (VEGFR2-targeted microbubbles), the vessels were segmented, and the spatial relationships between vessels and VEGFR2 targeting locations were analyzed. In five animals, an additional scan was performed in which the animal received a bolus of microbubbles targeted to E- and P-selectins. Vessel tortuosity as a function of distance from VEGF and selectin targeting was analyzed in these animals.

RESULTS

Although resulting differences in image intensity due to varying microbubble dose were not significant between the two lowest doses, superharmonic imaging had significantly higher contrast-to-tissue ratio (CTR) than multi-pulse imaging (mean across all doses 13.98 dB for molecular acoustic angiography vs. 0.53 dB for multi-pulse imaging; p = 4.9 × 10^-10). Analysis of registered microvascular and molecular imaging volumes indicated that vessel tortuosity decreases with increasing distance from both VEGFR2- and selectin-targeting sites.

CONCLUSIONS

Molecular acoustic angiography (superharmonic molecular imaging) exhibited a significant increase in CTR at all doses tested due to superior rejection of tissue artifact signals. Due to the high resolution of acoustic angiography molecular imaging, it is possible to analyze spatial relationships in aligned microvascular and molecular superharmonic imaging volumes. Future studies are required to separate the effects of biomarker expression and blood flow kinetics in comparing local tortuosity differences between different endothelial markers such as VEGFR2, E-selectin, and P-selectin.

Gold Nanoprobe-Enabled Three-Dimensional Ozone Imaging by Optical Coherence Tomography

Ozone (O₃) would be harmful to human skin for its strong oxidizing property, especially when stratum corneum or corneal epithelium is wounded. Imaging the penetration and distribution of ozone at depth is beneficial for studying the influence of ozone on skin or eyes. Here, we introduced a facile method for three-dimensional (3D) imaging of the penetration of O₃ into the anterior chamber of an isolated crucian carp eye by using optical coherence tomography (OCT) combined with gold triangular nanoprisms (GTNPs) as the contrast agent and molecular probe. We illustrated the specific response of GTNPs to ozone and demonstrated that GTNPs can function as an efficient nanoprobe for sensing O₃. The stabilities of GTNPs in different biologic solutions, as well as the signal intensity of GTNPs on an OCT imaging system, were investigated. Visualization of 3D penetration and distribution of O₃ in the biologic tissue was proved for the first time. The quantitative analysis of O₃ diffusion in the anterior chamber of the fish eye revealed a penetration depth of 311 μm within 172 min. Due to the strong scattering, near-infrared extinction band, and easy functionalization of GTNPs, they could further serve as nanoprobes for 3D OCT or multimodal imaging of other molecules or ions in the future.

Nanostructured Materials Synthesis Using Ultrasound

Recent applications of ultrasound to the production of nanostructured materials are reviewed. Sonochemistry permits the production of novel materials or provides a route to known materials without the need for high bulk temperatures, pressures, or long reaction times. Both chemical and physical phenomena associated with high-intensity ultrasound are responsible for the production or modification of nanomaterials. Most notable are the consequences of acoustic cavitation: the formation, growth, and implosive collapse of bubbles, and can be categorized as primary sonochemistry (gas-phase chemistry occurring inside collapsing bubbles), secondary sonochemistry (solution-phase chemistry occurring outside the bubbles), and physical modifications (caused by high-speed jets, shockwaves, or inter-particle collisions in slurries).

Low-Dose Molecular Ultrasound Imaging with E-Selectin-Targeted PBCA Microbubbles

PURPOSE

Our objective was to determine the lowest diagnostically effective dose for E-selectin-targeted poly n-butyl cyanoacrylate (PBCA)-shelled microbubbles and to apply it to monitor antiangiogenic therapy effects.

PROCEDURES

PBCA-shelled microbubbles (MBs) coupled to an E-selectin-specific peptide were applied in mice carrying MLS or A431 carcinoma xenografts scaling down the MB dosage to the lowest level where binding could be examined with a 18-MHz small animal ultrasound transducer. Differences in E-selectin expression in the two carcinoma xenografts were confirmed by enzyme-linked immunosorbent assay (ELISA). In addition, MLS tumor-bearing mice under antiangiogenic therapy were monitored using E-selectin-targeted MBs at the lowest applicable dose. Therapy effects on tumor vascularization were verified by immunohistological analyses.

RESULTS

The minimally required dosage was 7 × 10(7) MBs/kg body weight. This dosage was sufficient to enable E-selectin detection in high E-selectin-expressing MLS tumors, while low E-selectin-expressing A431 tumors required almost 2.5-fold higher doses. At the dose of 7 × 10(7) MBs/kg body weight, a decrease in E-selectin MB binding under antiangiogenic therapy could be assessed (being significant after 3 days of treatment; p < 0.0001), which was in line with the significant drop in E-selectin-positive area fractions that was found histologically (p < 0.05).

CONCLUSIONS

Molecular ultrasound imaging with our E-selectin-targeted MB and therapy monitoring was possible down to a dose of 7 × 10(7) MBs/kg body weight (equates to 66 μg PBCA/kg and 4.6 mg PBCA/70 kg). Improvements in choice of targets, MB composition, and other MB detection methods may improve sensitivity and lead to reliable detection results of clinically transferrable MBs at even lower dosage levels.

Magnetic and Plasmonic Contrast Agents in Optical Coherence Tomography

Optical coherence tomography (OCT) has gained widespread application for many biomedical applications, yet the traditional array of contrast agents used in incoherent imaging modalities do not provide contrast in OCT. Owing to the high biocompatibility of iron oxides and noble metals, magnetic and plasmonic nanoparticles, respectively, have been developed as OCT contrast agents to enable a range of biological and pre-clinical studies. Here we provide a review of these developments within the past decade, including an overview of the physical contrast mechanisms and classes of OCT system hardware addons needed for magnetic and plasmonic nanoparticle contrast. A comparison of the wide variety of nanoparticle systems is also presented, where the figures of merit depend strongly upon the choice of biological application.

Intravascular magnetomotive optical coherence tomography of targeted early-stage atherosclerotic changes in ex vivo hyperlipidemic rabbit aortas

We report the development of an intravascular magnetomotive optical coherence tomography (IV-MM-OCT) system used with targeted protein microspheres to detect early-stage atherosclerotic fatty streaks/plaques. Magnetic microspheres (MSs) were injected in vivo in rabbits, and after 30 minutes of in vivo circulation, excised ex vivo rabbit aorta samples specimens were then imaged ex vivo with our prototype IV-MM-OCT system. The alternating magnetic field gradient was provided by a unique pair of external custom-built electromagnetic coils that modulated the targeted magnetic MSs. The results showed a statistically significant MM-OCT signal from the aorta samples specimens injected with targeted MSs.

Enhancement and wavelength-shifted emission of Cerenkov luminescence using multifunctional microspheres

Cerenkov luminescence (CL) imaging is a new molecular imaging modality that utilizes the photons emitted during radioactive decay when charged particles travel faster than the phase velocity of light in a dielectric medium. Here we present a novel agent to convert and increase CL emission at longer wavelengths using multimodal protein microspheres (MSs). The (64)Cu-labeled protein microspheres contain quantum dots (QDs) encapsulated within a high-refractive-index-oil core. Dark box imaging of the MSs was conducted to demonstrate the improvement in CL emission at longer wavelengths. To illustrate the versatile design of these MSs and the potential of CL in disease diagnosis, these MSs were utilized for in vitro cell targeting and ex vivo CL-excited QD fluorescence (CL-FL) imaging of atherosclerotic plaques in rats. It was shown that by utilizing both QDs and MSs with a high-refractive-index-oil core, the CL emission increases by four-fold at longer wavelengths. Furthermore, we demonstrate that these MSs generate both an in vivo and ex vivo contrast signal. The design concept of utilizing QDs and high-index core MSs may contribute to future developments of in vivo CL imaging.

Targeted nanotechnology for cancer imaging

Targeted nanoparticle imaging agents provide many benefits and new opportunities to facilitate accurate diagnosis of cancer and significantly impact patient outcome. Due to the highly engineerable nature of nanotechnology, targeted nanoparticles exhibit significant advantages including increased contrast sensitivity, binding avidity and targeting specificity. Considering the various nanoparticle designs and their adjustable ability to target a specific site and generate detectable signals, nanoparticles can be optimally designed in terms of biophysical interactions (i.e., intravascular and interstitial transport) and biochemical interactions (i.e., targeting avidity towards cancer-related biomarkers) for site-specific detection of very distinct microenvironments. This review seeks to illustrate that the design of a nanoparticle dictates its in vivo journey and targeting of hard-to-reach cancer sites, facilitating early and accurate diagnosis and interrogation of the most aggressive forms of cancer. We will report various targeted nanoparticles for cancer imaging using X-ray computed tomography, ultrasound, magnetic resonance imaging, nuclear imaging and optical imaging. Finally, to realize the full potential of targeted nanotechnology for cancer imaging, we will describe the challenges and opportunities for the clinical translation and widespread adaptation of targeted nanoparticles imaging agents.

Magnetomotive optical coherence tomography for the assessment of atherosclerotic lesions using αvβ3 integrin-targeted microspheres

PURPOSE

We investigated the early-stage fatty streaks/plaques detection using magnetomotive optical coherence tomography (MM-OCT) in conjunction with αvβ3 integrin-targeted magnetic microspheres (MSs). The targeting of functionalized MSs was investigated by perfusing ex vivo aortas from an atherosclerotic rabbit model in a custom-designed flow chamber at physiologically relevant pulsatile flow rates and pressures.

PROCEDURES

Aortas were extracted and placed in a flow chamber. Magnetic MS contrast agents were perfused through the aortas and MM-OCT, fluorescence confocal, and bright field microscopy were performed on the ex vivo aorta specimens for localizing the MSs.

RESULTS

The results showed a statistically significant and stronger MM-OCT signal (3.30 ± 1.73 dB) from the aorta segment perfused with targeted MSs, compared with the nontargeted MSs (1.18 ± 0.94 dB) and control (0.78 ± 0.41 dB) aortas. In addition, there was a good co-registration of MM-OCT signals with confocal microscopy.

CONCLUSIONS

Early-stage fatty streaks/plaques have been successfully detected using MM-OCT in conjunction with αvβ3 integrin-targeted magnetic MSs.

Molecular Imaging in Optical Coherence Tomography

Optical coherence tomography (OCT) is a medical imaging technique that provides tomographic images at micron scales in three dimensions and high speeds. The addition of molecular contrast to the available morphological image holds great promise for extending OCT's impact in clinical practice and beyond. Fundamental limitations prevent OCT from directly taking advantage of powerful molecular processes such as fluorescence emission and incoherent Raman scattering. A wide range of approaches is being researched to provide molecular contrast to OCT. Here we review those approaches with particular attention to those that derive their molecular contrast directly from modulation of the OCT signal. We also provide a brief overview of the multimodal approaches to gaining molecular contrast coincident with OCT.

Sono-assembly of highly biocompatible polysaccharide capsules for hydrophobic drug delivery

Cells like sugar. General synthesis and potential of intracellular hydrophobic drug delivery of single-component polysaccharide capsules are pursued. The capsules can be generally assembled through hydrogen bonding networks but show striking shell robustness. The evidenced cell internalization, stimuli-responsiveness to local pH changes and high biocompatibilities of the capsules specifically favor their potential intracellular drug delivery.

High Resolution Phase-Sensitive Magnetomotive Optical Coherence Microscopy for Tracking Magnetic Microbeads and Cellular Mechanics

We present a real-time multimodal near-infrared imaging technology that tracks externally induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM).MPMis utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells.

Advance of molecular imaging technology and targeted imaging agent in imaging and therapy

Molecular imaging is an emerging field that integrates advanced imaging technology with cellular and molecular biology. It can realize noninvasive and real time visualization, measurement of physiological or pathological process in the living organism at the cellular and molecular level, providing an effective method of information acquiring for diagnosis, therapy, and drug development and evaluating treatment of efficacy. Molecular imaging requires high resolution and high sensitive instruments and specific imaging agents that link the imaging signal with molecular event. Recently, the application of new emerging chemical technology and nanotechnology has stimulated the development of imaging agents. Nanoparticles modified with small molecule, peptide, antibody, and aptamer have been extensively applied for preclinical studies. Therapeutic drug or gene is incorporated into nanoparticles to construct multifunctional imaging agents which allow for theranostic applications. In this review, we will discuss the characteristics of molecular imaging, the novel imaging agent including targeted imaging agent and multifunctional imaging agent, as well as cite some examples of their application in molecular imaging and therapy.

Nanoparticles for multimodal in vivo imaging in nanomedicine

While nanoparticles are usually designed for targeted drug delivery, they can also simultaneously provide diagnostic information by a variety of in vivo imaging methods. These diagnostic capabilities make use of specific properties of nanoparticle core materials. Near-infrared fluorescent probes provide optical detection of cells targeted by real-time nanoparticle-distribution studies within the organ compartments of live, anesthetized animals. By combining different imaging modalities, we can start with deep-body imaging by magnetic resonance imaging or computed tomography, and by using optical imaging, get down to the resolution required for real-time fluorescence-guided surgery.

Sonochemical synthesis of nanomaterials

High intensity ultrasound can be used for the production of novel materials and provides an unusual route to known materials without bulk high temperatures, high pressures, or long reaction times. Several phenomena are responsible for sonochemistry and specifically the production or modification of nanomaterials during ultrasonic irradiation. The most notable effects are consequences of acoustic cavitation (the formation, growth, and implosive collapse of bubbles), and can be categorized as primary sonochemistry (gas-phase chemistry occurring inside collapsing bubbles), secondary sonochemistry (solution-phase chemistry occurring outside the bubbles), and physical modifications (caused by high-speed jets or shock waves derived from bubble collapse). This tutorial review provides examples of how the chemical and physical effects of high intensity ultrasound can be exploited for the preparation or modification of a wide range of nanostructured materials.

Cyanine 5.5 conjugated nanobubbles as a tumor selective contrast agent for dual ultrasound-fluorescence imaging in a mouse model

Nanobubbles and microbubbles are non-invasive ultrasound imaging contrast agents that may potentially enhance diagnosis of tumors. However, to date, both nanobubbles and microbubbles display poor in vivo tumor-selectivity over non-targeted organs such as liver. We report here cyanine 5.5 conjugated nanobubbles (cy5.5-nanobubbles) of a biocompatible chitosan-vitamin C lipid system as a dual ultrasound-fluorescence contrast agent that achieved tumor-selective imaging in a mouse tumor model. Cy5.5-nanobubble suspension contained single bubble spheres and clusters of bubble spheres with the size ranging between 400-800 nm. In the in vivo mouse study, enhancement of ultrasound signals at tumor site was found to persist over 2 h while tumor-selective fluorescence emission was persistently observed over 24 h with intravenous injection of cy5.5-nanobubbles. In vitro cell study indicated that cy5.5-flurescence dye was able to accumulate in cancer cells due to the unique conjugated nanobubble structure. Further in vivo fluorescence study suggested that cy5.5-nanobubbles were mainly located at tumor site and in the bladder of mice. Subsequent analysis confirmed that accumulation of high fluorescence was present at the intact subcutaneous tumor site and in isolated tumor tissue but not in liver tissue post intravenous injection of cy5.5-nanobubbles. All these results led to the conclusion that cy5.5-nanobubbles with unique crosslinked chitosan-vitamin C lipid system have achieved tumor-selective imaging in vivo.

Dual-coil magnetomotive optical coherence tomography for contrast enhancement in liquids

Magnetomotive optical coherence tomography (MM-OCT) is a functional extension of OCT which utilizes magnetically responsive materials that are modulated by an external magnetic field for contrast enhancement and for elastography to assess the structural and viscoelastic properties of the surrounding tissues. Traditionally, magnetomotive contrast relies on the interaction between the displacement of magnetic particles induced by an external magnetic field and the micro-environmental restoring (elastic) force acting on the particles. When the restoring force from a sample containing magnetic particles is weak or non-existent, the MM-OCT signal-to-noise ratio (SNR) can degrade significantly. We have developed a novel solenoid configuration to enable MM-OCT imaging in samples that do not have an elastic restoring force, such as liquids. This coil configuration may potentially enable real-time MM-OCT imaging.