Nanomedicine strategies for molecular targets with MRI and optical imaging

Protein-guided biomimetic nanomaterials: a versatile theranostic nanoplatform for biomedical applications

Over the years, bioinspired mineralization-based approaches have been applied to synthesize multifunctional organic-inorganic nanocomposites. These nanocomposites can address the growing demands of modern biomedical applications. Proteins, serving as vital biological templates, play a pivotal role in the nucleation and growth processes of various organic-inorganic nanocomposites. Protein-mineralized nanomaterials (PMNMs) have attracted significant interest from researchers due to their facile and convenient preparation, strong physiological activity, stability, impressive biocompatibility, and biodegradability. Nevertheless, few comprehensive reviews have expounded on the progress of these nanomaterials in biomedicine. This article systematically reviews the principles and strategies for constructing nanomaterials using protein-directed biomineralization and biomimetic mineralization techniques. Subsequently, we focus on their recent applications in the biomedical field, encompassing areas such as bioimaging, as well as anti-tumor, anti-bacterial, and anti-inflammatory therapies. Furthermore, we discuss the challenges encountered in practical applications of these materials and explore their potential in future applications. This review aspired to catalyze the continued development of these bioinspired nanomaterials in drug development and clinical diagnosis, ultimately contributing to the fields of precision medicine and translational medicine.

Visualizing the Nucleome Using the CRISPR–Cas9 System: From in vitro to in vivo

One of the latest methods in modern molecular biology is labeling genomic loci in living cells using fluorescently labeled Cas protein. The NIH Foundation has made the mapping of the 4D nucleome (the three-dimensional nucleome on a timescale) a priority in the studies aimed to improve our understanding of chromatin organization. Fluorescent methods based on CRISPR-Cas are a significant step forward in visualization of genomic loci in living cells. This approach can be used for studying epigenetics, cell cycle, cellular response to external stimuli, rearrangements during malignant cell transformation, such as chromosomal translocations or damage, as well as for genome editing. In this review, we focused on the application of CRISPR-Cas fluorescence technologies as components of multimodal imaging methods for in vivo mapping of chromosomal loci, in particular, attribution of fluorescence signal to morphological and anatomical structures in a living organism. The review discusses the approaches to the highly sensitive, high-precision labeling of CRISPR-Cas components, delivery of genetically engineered constructs into cells and tissues, and promising methods for molecular imaging.

Theranostic Nanomedicines for the Treatment of Cardiovascular and Related Diseases: Current Strategies and Future Perspectives

Cardiovascular and related diseases (CVRDs) are among the most prevalent chronic diseases in the 21st century, with a high mortality rate. This review summarizes the various nanomedicines for diagnostic and therapeutic applications in CVRDs, including nanomedicine for angina pectoris, myocarditis, myocardial infarction, pericardial disorder, thrombosis, atherosclerosis, hyperlipidemia, hypertension, pulmonary arterial hypertension and stroke. Theranostic nanomedicines can prolong systemic circulation, escape from the host defense system, and deliver theranostic agents to the targeted site for imaging and therapy at a cellular and molecular level. Presently, discrete non-invasive and non-surgical theranostic methodologies are such an advancement modality capable of targeted diagnosis and therapy and have better efficacy with fewer side effects than conventional medicine. Additionally, we have presented the recent updates on nanomedicine in clinical trials, targeted nanomedicine and its translational challenges for CVRDs. Theranostic nanomedicine acts as a bridge towards CVRDs amelioration and its management.

Organic nanoparticle tracking during pharmacokinetic studies

To understand how nanoparticles (NPs) interact with biological barriers and to ensure they maintain their integrity over time, it is crucial to study their in vivo pharmacokinetic (PK) profiles. Many methods of tracking have been used to describe the in vivo fate of NPs and to evaluate their PKs and structural integrity. However, they do not deliver the same level of information and this may cause misinterpretations. Here, the authors review and discuss the different methods for in vivo tracking of organic NPs. Among them, Förster resonance energy transfer (FRET) presents great potential to track NPs' integrity. However, FRET still requires validated methods to extract and quantify NPs in biological fluids and tissues.

Molecular magnetic resonance imaging of Alpha-v-Beta-3 integrin expression in tumors with ultrasound microbubbles

Microbubbles (MB) are used as ultrasound (US) contrast agents and can be efficiently targeted against markers of angiogenesis and inflammation. Due to their gas core, MB locally alter susceptibilities in magnetic resonance imaging (MRI), but unfortunately, the resulting contrast is low and not sufficient to generate powerful molecular MRI probes. Therefore, we investigated whether a potent molecular MR agent can be generated by encapsulating superparamagnetic iron oxide nanoparticles (SPION) in the polymeric shell of poly (n-butylcyanoacrylate) (PBCA) MB and targeted them against α_vβ₃ integrins on the angiogenic vasculature of 4T1 murine breast carcinomas. SPION-MB consist of an air core and a multi-layered polymeric shell enabling efficient entrapment of SPION. The mean size of SPION-MB was 1.61 ± 0.32 μm. Biotin-streptavidin coupling was employed to functionalize the SPION-MB with cyclic RGDfK (Arg-Gly-Asp) and RADfK (Arg-Ala-Asp) peptides. Cells incubated with RGD-SPION-MB showed enhanced transverse relaxation rates compared with SPION-MB and blocking α_vβ₃ integrin receptors with excess free cRGDfK significantly reduced RGD-SPION-MB binding. Due to the fast binding of RGD-SPION-MB in vivo, dynamic susceptibility contrast MRI was employed to track their retention in tumors in real-time. Higher retention of RGD-SPION-MB was observed compared with SPION-MB and RAD-SPION-MB. To corroborate our MRI results, molecular US was performed the following day using the destruction-replenishment method. Both imaging modalities consistently indicated higher retention of RGD-SPION-MB in angiogenic vessels compared with SPION-MB and RAD-SPION-MB. Competitive blocking experiments in mice further confirmed that the binding of RGD-SPION-MB to α_vβ₃ integrin receptors is specific. Overall, this study demonstrates that RGD-SPION-MB can be employed as molecular MR/US contrast agents and are capable of assessing the α_vβ₃ integrin expression in the neovasculature of malignant tumors.

Albumin-based nanoparticles as contrast medium for MRI: vascular imaging, tissue and cell interactions, and pharmacokinetics of second-generation nanoparticles

This multidisciplinary study examined the pharmacokinetics of nanoparticles based on albumin-DTPA-gadolinium chelates, testing the hypothesis that these nanoparticles create a stronger vessel signal than conventional gadolinium-based contrast agents and exploring if they are safe for clinical use. Nanoparticles based on human serum albumin, bearing gadolinium and designed for use in magnetic resonance imaging, were used to generate magnet resonance images (MRI) of the vascular system in rats ("blood pool imaging"). At the low nanoparticle doses used for radionuclide imaging, nanoparticle-associated metals were cleared from the blood into the liver during the first 4 h after nanoparticle application. At the higher doses required for MRI, the liver became saturated and kidney and spleen acted as additional sinks for the metals, and accounted for most processing of the nanoparticles. The multiple components of the nanoparticles were cleared independently of one another. Albumin was detected in liver, spleen, and kidneys for up to 2 days after intravenous injection. Gadolinium was retained in the liver, kidneys, and spleen in significant concentrations for much longer. Gadolinium was present as significant fractions of initial dose for longer than 2 weeks after application, and gadolinium clearance was only complete after 6 weeks. Our analysis could not account quantitatively for the full dose of gadolinium that was applied, but numerous organs were found to contain gadolinium in the collagen of their connective tissues. Multiple lines of evidence indicated intracellular processing opening the DTPA chelates and leading to gadolinium long-term storage, in particular inside lysosomes. Turnover of the stored gadolinium was found to occur in soluble form in the kidneys, the liver, and the colon for up to 3 weeks after application. Gadolinium overload poses a significant hazard due to the high toxicity of free gadolinium ions. We discuss the relevance of our findings to gadolinium-deposition diseases.

Perfluorocarbons-Based 19F Magnetic Resonance Imaging in Biomedicine

Fluorine-19 (¹⁹F) magnetic resonance (MR) molecular imaging is a promising noninvasive and quantitative molecular imaging approach with intensive research due to the high sensitivity and low endogenous background signal of the ¹⁹F atom in vivo. Perfluorocarbons (PFCs) have been used as blood substitutes since 1970s. More recently, a variety of PFC nanoparticles have been designed for the detection and imaging of physiological and pathological changes. These molecular imaging probes have been developed to label cells, target specific epitopes in tumors, monitor the prognosis and therapy efficacy and quantitate characterization of tumors and changes in tumor microenvironment noninvasively, therefore, significantly improving the prognosis and therapy efficacy. Herein, we discuss the recent development and applications of ¹⁹F MR techniques with PFC nanoparticles in biomedicine, with particular emphasis on ligand-targeted and quantitative ¹⁹F MR imaging approaches for tumor detection, oxygenation measurement, smart stimulus response and therapy efficacy monitoring, et al.

Bright Ferritin-a Reporter Gene Platform for On-Demand, Longitudinal Cell Tracking on MRI

A major unresolved challenge in cell-based regenerative medicine is the absence of non-invasive technologies for tracking cell fate in deep tissue and with high spatial resolution over an extended interval. MRI is highly suited for this task, but current methods fail to provide longitudinal monitoring or high sensitivity, or both. In this study, we fill this technological gap with the first discovery and demonstration of in vivo cellular production of endogenous bright contrast via an MRI genetic reporter system that forms manganese-ferritin nanoparticles. We demonstrate this technology in human embryonic kidney cells genetically modified to stably overexpress ferritin and show that, in the presence of manganese, these cells produce far greater contrast than conventional ferritin overexpression with iron or manganese-permeable cells. In living mice, diffusely implanted bright-ferritin cells produce the highest and most sustained contrast in skeletal muscle. The bright-ferritin platform has potential for on-demand, longitudinal, and sensitive cell tracking in vivo.

Highly Luminescent and Anti-Photobleaching Core-Shell Structure of Mesoporous Silica and Phosphatidylcholine Modified Superparamagnetic Iron Oxide Nanoparticles

Highly fluorescent magnetic nanoparticles (Eu(TTA)₃(P(Oct)₃)₃@mSiO₂@SPION) [europium (III) chloride hexahydrate = Eu; 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione = TTA; trioctylphosphine = (P(Oct)₃); mesoporous silica = mSiO₂; superparamagnetic iron oxide nanoparticle = SPION] were developed as a dual-functional imaging agent. The hierarchical structure was composed of a magnetic core and mesoporous silica shell was constructed using a cationic surfactant template after coating with phosphatidylcholine of oleic acid coated SPION. Afterward, the surface and cavities of mSiO₂@SPION were modified with 3-(trimethoxysilyl) propyl methacrylate (TMSPMA) as a silane coupling agent to introduce methacrylate groups. Eu(TTA)₃(P(Oct)₃)₃ molecules are penetrated, located and bonded covalently inside of the cavities/mesopores of mSiO₂, it shows extremely stable anti-photobleaching properties. The emission spectra of Eu(TTA)₃(P(Oct)₃)₃@mSiO₂@SPION indicated typical hypersensitivity transition ⁵D₀→⁷F₂ at 621 nm. The concentration of Eu(TTA)₃(P(Oct)₃)₃@mSiO₂@SPION was varied between 10 and 500 μL/mL to evaluate the cytotoxicity with NCI-H460 (H460) cells using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. In addition, the presence of a strong red-emitting Eu(TTA)₃(P(Oct)₃)₃@mSiO₂@SPION in the cytoplasm was observed by fluorescence microscopy. Those results that it can be a potential candidate for dual-functional contrast agent and PL nanomaterials for fabricating the diagnostic kits to amplify the low signal.

Comparative study on contrast enhancement of Magnevist and Magnevist-loaded nanoparticles in pancreatic cancer PDX model monitored by MRI

Background:

The aim of this study was to compare contrast enhancement of Magnevist® (gadopentate dimeglumine (Mag)) to that of PEGylated Magnevist®-loaded liposomal nanoparticles (Mag-Lnps) in pancreatic cancer patient-derived xenograft (PDX) mouse model via magnetic resonance imaging (MRI).

Methods:

Mag-Lnps formulated by thin-film hydration and extrusion was characterized for the particle size and zeta potential. A 21.1 T vertical magnet was used for all MRI. The magnet was equipped with a Bruker Advance console and ParaVision 6.1 acquisitions software. Mag-Lnps phantoms were prepared and imaged with a 10-mm birdcage coil. For in vivo imaging, animals were sedated and injected with a single dose (4 mg/kg) of Mag or Mag-Lnps with Mag equivalent dose. Using a 33-mm inner diameter birdcage coil, T₁ maps were acquired, and signal to noise ratio (SNR) measured for 2 h.

Results:

Mag-Lnps phantoms showed a remarkable augmentation in contrast with Mag increment. However, in in vivo imaging, no significant difference in contrast was observed between Mag and MRI. While Mag-Lnps was observed to have fairly high tumor/muscle (T/M) ratio in the first 30 min, free Mag exhibited higher T/M ratio over the time-period between 30 and 120 min. Overall, there was no statistically significant difference between Mag and Mag-Lnp in rating MR image quality. Low payload of Mag entrapment by Lnps and restricted access of water (protons) to Mag-Lnps may have affected the performance of Mag-Lnps as an effective contrast agent.

Conclusion:

This study showed no significance difference in MRI contrast between Mag and Mag-Lnp pancreatic cancer PDX mouse models.

Theranostic application of nanoemulsions in chemotherapy

Theranostics has the potential to revolutionize the diagnosis, treatment, and prognosis of cancer, where novel drug delivery systems could be used to detect the disease at an early stage with instantaneous treatment. Various preclinical approaches of nanoemulsions with entrapped contrast and chemotherapeutic agents have been documented to act specifically on the tumor microenvironment (TME) for both diagnostic and therapeutic purposes. However, bringing these theranostic nanoemulsions through preclinical trials to patients requires several fundamental hurdles to be overcome, including the in vivo behavior of the delivery tool, degradation, and clearance from the system, as well as long-term toxicities. Here, we discuss recent advances in the application of nanoemulsions in molecular imaging with simultaneous therapeutic efficacy in a single delivery system.

Low Toxicity, High Resolution, and Red Tissue Imaging in the Vivo of Yb/Tm/GZO@SiO2 Core-Shell Upconversion Nanoparticles

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted great attention in bioimaging applications. However, the stability and resolution of bioimaging based on UCNPs should be further improved. Herein, we synthesized SiO₂-coated Ga(III)-doped ZnO (GZO) with lanthanide ion Yb(III) and Tm(III) (Yb/Tm/GZO@SiO₂) UCNPs, which realized red fluorescence imaging in heart tissue. With increasing injection concentrations of Yb/Tm/GZO@SiO₂ (1-10 mg/kg), the red fluorescence imaging intensity of heart tissue gradually increased. Moreover, the experimental results of toxicity in vitro and histological assessments of representative organs in vivo were studied, indicating that Yb/Tm/GZO@SiO₂ UCNPs had low biological toxicity. These results proved that Yb/Tm/GZO@SiO₂ can be used as a probe for fluorescence imaging in vivo.

Design and Synthesis of Gold-Gadolinium-Core-Shell Nanoparticles as Contrast Agent: a Smart Way to Future Nanomaterials for Nanomedicine Applications

INTRODUCTION

The development of biopolymers for the synthesis of Gd(III) nanoparticles, as therapeutics, could play a key role in nanomedicine. Biocompatible polymers are not only used for complex monovalent biomolecules, but also for the realization of multivalent active targeting materials as diagnostic and/or therapeutic hybrid nanoparticles. In this article, it was reported for the first time, a novel synthesis of Gd(III)-biopolymer-Au(III) complex, acting as a key ingredient of core-shell gold nanoparticles (Gd(@AuNPs).

MATERIAL AND METHODS

The physical and chemical evaluation was carried out by spectroscopic analytical techniques (Raman spectroscopy, UV-visible and TEM). The theoretical characterization by DFT (density functional theory) analysis was carried out under specific conditions to investigate the interaction between the Au and the Gd precursors, during the first nucleation step. Magnetic features with relaxivity measurements at 7T were also performed as well as cytotoxicity studies on hepatocyte cell lines for biocompatibility studies. The in vivo detailed dynamic biodistribution studies in mice to characterize the potential applications for biology as MRI contrast agents were then achieved.

RESULTS

Physical-chemical evaluation confirms the successful design and reaction supposed. Viabilities of TIB-75 (hepatocytes) cells were evaluated using Alamar blue cytotoxic tests with increasing concentrations of nanoparticles. In vivo biodistribution studies were then accomplished to assess the kinetic behavior of the nanoparticles in mice and characterize their stealthiness property after intravenous injection.

CONCLUSION

We demonstrated that Gd@AuNPs have some advantages to display hepatocytes in the liver. Particularly, these nanoconjugates give a good cellular uptake of several quantities of Gd@NPs into cells, while preserving a T1 contrast inside cells that provide a robust in vivo detection using T1-weighted MR images. These results will strengthen the role of gadolinium as complex to gold in order to tune Gd(@AuNPs) as an innovative diagnostic agent in the field of nanomedicine.

High Biocompatible ZIF-8 Coated by ZrO2 for Chemo-microwave Thermal Tumor Synergistic Therapy

The zeolitic imidazolate framework-8 (ZIF-8) is a specifically promising drug carrier due to its excellent intrinsic properties. However, the high toxicity of ZIF-8 nanoparticles severely limits their further research and clinical application. In this work, the biocompatibility of ZIF-8 nanoparticles is greatly improved by coating ZrO₂ onto the surface. The survival rate of cells and mice in the ZIF-8@ZrO₂ nanocomposite group is significantly increased compared with the undecorated ZIF-8 nanoparticle group. Doxorubicin (DOX) as a chemotherapeutic drug is deposited during the ZIF-8 growth by a facile one-pot method. Ionic liquid (IL) is loaded into the pore of the ZIF-8/DOX@ZrO₂ nanocomposites for enhancing microwave thermal therapy. The tumor inhibition rate of ZIF-8/DOX@ZrO₂@IL nanocomposites with synergistic microwave thermal therapy and chemotherapy is obviously higher than in other groups. In addition, the ZIF-8/DOX@ZrO₂@IL nanocomposites are used for real-time monitoring of the therapeutic outcomes due to the excellent computed tomography contrast agent, ZrO₂. Therefore, such a ZrO₂ coating strategy shows great promise for overcoming high toxicity of ZIF-8 nanoparticles, which offers a new platform for tumor synergistic microwave thermal therapy and chemotherapy using the ZIF-8/DOX@ZrO₂@IL nanocomposite as a theranostic nanocarrier.

A highly sensitive living probe derived from nanoparticle-remodeled neutrophils for precision tumor imaging diagnosis

Thiol activated, imaging agents loaded BSA nanoparticles were remodeled onto thiol-containing neutrophil surface through disulfide–thiol exchange for potential diagnosis applications.

Following nanomedicine activation with magnetic resonance imaging: why, how, and what's next?

Nanomedicines, such as liposomal formulations, play an important role in cancer therapy. To support their development, medical imaging modalities are employed for following the drug delivery. Encapsulation of MRI contrast agents, which change their relaxivity upon co-release with the drug, is a promising strategy for monitoring both the biodistribution and payload release from a nanocarrier. This approach is successfully applied in preclinical settings to image the activation of liposomes responsive to heat, pH changes or sonication. Recent advances include combination with different treatments and the implementation of chemical exchange saturation transfer imaging to gain spectral resolution over different contrast agents. However, this field still faces challenges, such as matching the pharmacokinetic profiles of the contrast agents and the liberated drugs.

Quantification of vascular damage in acute kidney injury with fluorine magnetic resonance imaging and spectroscopy

PURPOSE

To design a fluorine MRI/MR spectroscopy approach to quantify renal vascular damage after ischemia-reperfusion injury, and the therapeutic response to antithrombin nanoparticles (NPs) to protect kidney function.

METHODS

A total of 53 rats underwent 45 min of bilateral renal artery occlusion and were treated at reperfusion with either plain perfluorocarbon NPs or NPs functionalized with a direct thrombin inhibitor (PPACK:phenyalanine-proline-arginine-chloromethylketone). Three hours after reperfusion, kidneys underwent ex vivo fluorine MRI/MR spectroscopy at 4.7 T to quantify the extent and volume of trapped NPs, as an index of vascular damage and ischemia-reperfusion injury. Microscopic evaluation of structural damage and NP trapping in non-reperfused renal segments was performed. Serum creatinine was quantified serially over 7 days.

RESULTS

The damaged renal cortico-medullary junction trapped a significant volume of NPs (P = 0.04), which correlated linearly (r = 0.64) with the severity of kidney injury 3 h after reperfusion. Despite global large vessel reperfusion, non-reperfusion in medullary peritubular capillaries was confirmed by MRI and microscopy, indicative of continuing hypoxia due to vascular compromise. Treatment of animals with PPACK NPs after acute kidney injury did not accelerate kidney functional recovery.

CONCLUSIONS

Quantification of ischemia-reperfusion injury after acute kidney injury with fluorine MRI/MR spectroscopy of perfluorocarbon NPs objectively depicts the extent and severity of vascular injury and its linear relationship to renal dysfunction. The lack of kidney function improvement after early posttreatment thrombin inhibition confirms the rapid onset of ischemia-reperfusion injury as a consequence of vascular damage and non-reperfusion. The prolongation of medullary ischemia renders cortico-medullary tubular structures susceptible to continued necrosis despite restoration of large vessel flow, which suggests limitations to acute interventions after acute kidney injury, designed to interdict renal tubular damage. Magn Reson Med 79:3144-3153, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

White Paper on P4 Concepts for Pediatric Imaging

Over the past decade, innovations in the field of pediatric imaging have been based largely on single-center and retrospective studies, which provided limited advances for the benefit of pediatric patients. To identify opportunities for potential "quantum-leap" progress in the field of pediatric imaging, the ACR-Pediatric Imaging Research (PIR) Committee has identified high-impact research directions related to the P4 concept of predictive, preventive, personalized, and participatory diagnosis and intervention. Input from 237 members of the Society for Pediatric Radiology was clustered around 10 priority areas, which are discussed in this article. Needs within each priority area have been analyzed in detail by ACR-PIR experts on these topics. By facilitating work in these priority areas, we hope to revolutionize the care of children by shifting our efforts from unilateral reaction to clinical symptoms, to interactive maintenance of child health.

Recent Advances in Targeted, Self-Assembling Nanoparticles to Address Vascular Damage Due to Atherosclerosis

Self-assembling nanoparticles functionalized with targeting moieties have significant potential for atherosclerosis nanomedicine. While self-assembly allows the easy construction (and degradation) of nanoparticles with therapeutic or diagnostic functionality, or both, the targeting agent can direct them to a specific molecular marker within a given stage of the disease. Therefore, supramolecular nanoparticles have been investigated in the last decade as molecular imaging agents or explored as nanocarriers that can decrease the systemic toxicity of drugs by producing accumulation predominantly in specific tissues of interest. In this Progress Report, the pathogenesis of atherosclerosis and the damage caused to vascular tissue are described, as well as the current diagnostic and treatment options. An overview of targeted strategies using self-assembling nanoparticles is provided, including liposomes, high density lipoproteins, protein cages, micelles, proticles, and perfluorocarbon nanoparticles. Finally, an overview is given of current challenges, limitations, and future applications for personalized medicine in the context of atherosclerosis of self-assembling nanoparticles.

Imaging Tumor Necrosis with Ferumoxytol

OBJECTIVE

Ultra-small superparamagnetic iron oxide nanoparticles (USPIO) are promising contrast agents for magnetic resonance imaging (MRI). USPIO mediated proton relaxation rate enhancement is strongly dependent on compartmentalization of the agent and can vary depending on their intracellular or extracellular location in the tumor microenvironment. We compared the T1- and T2-enhancement pattern of intracellular and extracellular USPIO in mouse models of cancer and pilot data from patients. A better understanding of these MR signal effects will enable non-invasive characterizations of the composition of the tumor microenvironment.

MATERIALS AND METHODS

Six 4T1 and six MMTV-PyMT mammary tumors were grown in mice and imaged with ferumoxytol-enhanced MRI. R1 relaxation rates were calculated for different tumor types and different tumor areas and compared with histology. The transendothelial leakage rate of ferumoxytol was obtained by our measured relaxivity of ferumoxytol and compared between different tumor types, using a t-test. Additionally, 3 patients with malignant sarcomas were imaged with ferumoxytol-enhanced MRI. T1- and T2-enhancement patterns were compared with histopathology in a descriptive manner as a proof of concept for clinical translation of our observations.

RESULTS

4T1 tumors showed central areas of high signal on T1 and low signal on T2 weighted MR images, which corresponded to extracellular nanoparticles in a necrotic core on histopathology. MMTV-PyMT tumors showed little change on T1 but decreased signal on T2 weighted images, which correlated to compartmentalized nanoparticles in tumor associated macrophages. Only 4T1 tumors demonstrated significantly increased R1 relaxation rates of the tumor core compared to the tumor periphery (p<0.001). Transendothelial USPIO leakage was significantly higher for 4T1 tumors (3.4±0.9x10-3 mL/min/100cm3) compared to MMTV-PyMT tumors (1.0±0.9x10-3 mL/min/100 cm3). Likewise, ferumoxytol imaging in patients showed similar findings with high T1 signal in areas of tumor necrosis and low signal in areas of intracellularly compartmentalized iron.

CONCLUSION

Differential T1- and T2-enhancement patterns of USPIO in tumors enable conclusions about their intracellular and extracellular location. This information can be used to characterize the composition of the tumor microenvironment.

Ternary graphene quantum dot-polydopamine-Mn3O4 nanoparticles for optical imaging guided photodynamic therapy and T1-weighted magnetic resonance imaging

Imaging-guided therapy, which bridges treatment and diagnosis, plays an important role in overcoming the limitations of classical cancer therapy. To provide a more exact location of the tumor and to reduce side effects to normal tissues, a multifunctional probe was designed to serve as both an imaging agent and a therapeutic agent. Ternary hybrid nanoparticles comprised of visible red-responsive graphene, the T₁-weighted magnetic resonance imaging (MRI) agent Mn₃O₄ and a mussel-inspired linker polydopamine. The conjugation of graphene to Mn₃O₄ through polydopamine enhanced the water solubility of Mn₃O₄, enabling an efficient uptake by cancer cells as well as tumor accumulation when the nanoparticles were intravenously administered into mice. These nanoparticles, when localized at a tumor site, exhibited low cytotoxicity in the dark, while light irradiation of the cancer cells transfected with the nanoparticles resulted in significant phototherapeutic effects, apparently by generating toxic reactive oxygen species. These nanoparticles also allowed excellent T₁-weighted MR imaging in a human lung cancer xenograft model and were successfully used for combined visible red-imaging-guided photodynamic therapy and T₁-weighted MRI.

Molecular imaging for theranostics in gastroenterology: one stone to kill two birds

Molecular imaging in gastroenterology has become more feasible with recent advances in imaging technology, molecular genetics, and next-generation biochemistry, in addition to advances in endoscopic imaging techniques including magnified high-resolution endoscopy, narrow band imaging or autofluorescence imaging, flexible spectral imaging color enhancement, and confocal laser endomicroscopy. These developments have the potential to serve as "red flag" techniques enabling the earlier and accurate detection of mucosal abnormalities (such as precancerous lesions) beyond biomarkers, virtual histology of detected lesions, and molecular targeted therapy-the strategy of "one stone to kill two or three birds"; however, more effort should be done to be "blue ocean" benefit. This review deals with the introduction of Raman spectroscopy endoscopy, imaging mass spectroscopy, and nanomolecule development for theranostics. Imaging of molecular pathological changes in cells/tissues/organs might open the "royal road" to either convincing diagnosis of diseases that otherwise would only be detected in the advanced stages or novel therapeutic methods targeted to personalized medicine.

Perfluorocarbon nanoparticles: evolution of a multimodality and multifunctional imaging agent

Perfluorocarbon nanoparticles offer a biologically inert, highly stable, and nontoxic platform that can be specifically designed to accomplish a range of molecular imaging and drug delivery functions in vivo. The particle surface can be decorated with targeting ligands to direct the agent to a variety of biomarkers that are associated with diseases such as cancer, cardiovascular disease, obesity, and thrombosis. The surface can also carry a high payload of imaging agents, ranging from paramagnetic metals for MRI, radionuclides for nuclear imaging, iodine for CT, and florescent tags for histology, allowing high sensitivity mapping of cellular receptors that may be expressed at very low levels in the body. In addition to these diagnostic imaging applications, the particles can be engineered to carry highly potent drugs and specifically deposit them into cell populations that display biosignatures of a variety of diseases. The highly flexible and robust nature of this combined molecular imaging and drug delivery vehicle has been exploited in a variety of animal models to demonstrate its potential impact on the care and treatment of patients suffering from some of the most debilitating diseases.

Targeted in vivo imaging of microscopic tumors with ferritin-based nanoprobes across biological barriers

The avascular microscopic breast and brain tumors (<1-2 mm diameter) can be noninvasively detected by designing human heavy-chain ferritin (HFn)-based nanoparticles as molecular probes for near-infrared fluorescence and magnetic resonance imaging. The intravenously injected HFn-based nano-particles (Cy5.5-HFn and M-HFn) can cross the endothelium, epithelium, and blood-brain barriers and be internalized into tumor cells.

Visualizing the atherosclerotic plaque: a chemical perspective

Atherosclerosis is the major underlying pathologic cause of coronary artery disease. An early detection of the disease can prevent clinical sequellae such as angina, myocardial infarction, and stroke. The different imaging techniques employed to visualize the atherosclerotic plaque provide information of diagnostic and prognostic value. Furthermore, the use of contrast agents helps to improve signal-to-noise ratio providing better images. For nuclear imaging techniques and optical imaging these agents are absolutely necessary. We report on the different contrast agents that have been used, are used or may be used in future in animals, humans, or excised tissues for the distinct imaging modalities for atherosclerotic plaque imaging.

Nature-inspired nanoformulations for contrast-enhanced in vivo MR imaging of macrophages

Magnetic resonance imaging (MRI) of macrophages in atherosclerosis requires the use of contrast-enhancing agents. Reconstituted lipoprotein particles that mimic native high-density lipoproteins (HDL) are a versatile delivery platform for Gd-based contrast agents (GBCA) but require targeting moieties to direct the particles to macrophages. In this study, a naturally occurring methionine oxidation in the major HDL protein, apolipoprotein (apo) A-I, was exploited as a novel way to target HDL to macrophages. We also tested if fully functional GBCA-HDL can be generated using synthetic apo A-I peptides. The fluorescence and MRI studies reveal that specific oxidation of apo A-I or its peptides increases the in vitro macrophage uptake of GBCA-HDL by 2-3 times. The in vivo imaging studies using an apo E-deficient mouse model of atherosclerosis and a 3.0 T MRI system demonstrate that this modification significantly improves atherosclerotic plaque detection using GBCA-HDL. At 24 h post-injection of 0.05 mmol Gd kg(-1) GBCA-HDL containing oxidized apo A-I or its peptides, the atherosclerotic wall/muscle normalized enhancement ratios were 90 and 120%, respectively, while those of GBCA-HDL containing their unmodified counterparts were 35 and 45%, respectively. Confocal fluorescence microscopy confirms the accumulation of GBCA-HDL containing oxidized apo A-I or its peptides in intraplaque macrophages. Together, the results of this study confirm the hypothesis that specific oxidation of apo A-I targets GBCA-HDL to macrophages in vitro and in vivo. Furthermore, our observation that synthetic peptides can functionally replace the native apo A-I protein in HDL further encourages the development of these contrast agents for macrophage imaging.

Magnetically guided survivin-siRNA delivery and simultaneous dual-modal imaging visualization based on Fe3O4@mTiO2nanospheres for breast cancer

Fe₃O₄@mTiO₂/FMN-PEI as a siRNA delivery system can transfect survivin-siRNA to induce apoptosis, along with magnetic targeting, MRI and optical imaging.

Nanopsychiatry--the potential role of nanotechnologies in the future of psychiatry: a systematic review

Nanomedicine is defined as the area using nanotechnology's concepts for the benefit of human beings' health and well being. In this article, we aimed to provide an overview of areas where nanotechnology is applied and how they could be extended to care for psychiatric illnesses. The main applications of nanotechnology in psychiatry are (i) pharmacology. There are two main difficulties in neuropharmacology: drugs have to pass the blood-brain barrier and then to be internalized by targeted cells. Nanoparticles could increase drugs bioavailability and pharmacokinetics, especially improving safety and efficacy of psychotropic drugs. Liposomes, nanosomes, nanoparticle polymers, nanobubbles are some examples of this targeted drug delivery. Nanotechnologies could also add new pharmacological properties, like nanoshells and dendrimers (ii) living analysis. Nanotechnology provides technical assistance to in vivo imaging or metabolome analysis (iii) central nervous system modeling. Research teams have succeeded to modelize inorganic synapses and mimick synaptic behavior, a step essential for further creation of artificial neural systems. Some nanoparticle assemblies present the same small worlds and free-scale networks architecture as cortical neural networks. Nanotechnologies and quantum physics could be used to create models of artificial intelligence and mental illnesses. We are not about to see a concrete application of nanomedicine in daily psychiatric practice. Even if nanotechnologies are promising, their safety is still inconsistent and this must be kept in mind. However, it seems essential that psychiatrists do not forsake this area of research the perspectives of which could be decisive in the field of mental illness.

Detection of (19)F-labeled biopharmaceuticals in cell cultures with magnetic resonance

Magnetic resonance (MR) studies of the therapeutic efficacy of fluorinated drugs have recently become possible due to improvements in detection including the application of very strong magnetic fields up to 9.4Tesla (T). These advances allow tracking, identification, and quantification of (19)F-labeled biopharmaceuticals using (19)F MR imaging ((19)F MRI) and spectroscopy ((19)F MRS). Both techniques are noninvasive, are nondestructive, and enable serial measurements. They also allow for controlled and systematic studies of cellular metabolism in cancerous tissue in vivo (small animals and humans) and in vitro (body fluids, cells culture, tissue extracts and isolated tissues). Here we provide an overview of the (19)F MRI and (19)F MRS techniques used for tracking (19)F labeled anticancer chemotherapeutics and antibodies which allow quantification of drug uptake in cancer cells in vitro.

Multimodal iron oxide nanoparticles for hybrid biomedical imaging

Iron oxide core nanoparticles are attractive imaging agents because their material properties allow the tuning of pharmacokinetics as well as the attachment of multiple moieties to their surface. In addition to affinity ligands, these include fluorochromes and radioisotopes for detection with optical and nuclear imaging. As the iron oxide core can be detected by MRI, options for combining imaging modalities are manifold. Already, preclinical imaging strategies have combined noninvasive imaging with higher resolution techniques, such as intravital microscopy, to gain unprecedented insight into steady-state biology and disease. Going forward, hybrid iron oxide nanoparticles will help to merge modalities, creating a synergy that will enable imaging in basic research and, potentially, also in the clinic.

[Nanopsychiatry. The potential role of nanotechnologies in the future of psychiatry. A systematic review]

INTRODUCTION

Nanomedicine is defined as the area using nanotechnology's concepts for the benefit of human beings, their health and well being. The field of nanotechnology opened new unsuspected fields of research a few years ago.

AIM OF THE STUDY

To provide an overview of nanotechnology application areas that could affect care for psychiatric illnesses.

METHODS

We conducted a systematic review using the PRISMA criteria (preferred reporting items for systematic reviews and meta-analysis). Inclusion criteria were specified in advance: all studies describing the development of nanotechnology in psychiatry. The research paradigm was: "(nanotechnology OR nanoparticles OR nanomedicine) AND (central nervous system)" Articles were identified in three research bases, Medline (1966-present), Web of Science (1975-present) and Cochrane (all articles). The last search was carried out on April 2, 2012. Seventy-six items were included in this qualitative review.

RESULTS

The main applications of nanotechnology in psychiatry are (i) pharmacology. There are two main difficulties in neuropharmacology. Drugs have to pass the blood brain barrier and then to be internalized by targeted cells. Nanoparticles could increase drugs' bioavailability and pharmacokinetics, especially improving safety and efficacy of psychotropic drugs. Liposomes, nanosomes, nanoparticle polymers, nanobubbles are some examples of this targeted drug delivery. Nanotechnologies could also add new pharmacological properties, like nanohells and dendrimers; (ii) living analysis. Nanotechnology provides technical assistance to in vivo imaging or metabolome analysis; (iii) central nervous system modeling. Research teams have modelized inorganic synapses and mimicked synaptic behavior, essential for further creation of artificial neural systems. Some nanoparticle assemblies present the same small world and free-scale network architecture as cortical neural networks. Nanotechnologies and quantum physics could be used to create models of artificial intelligence and mental illnesses.

DISCUSSION

Even if nanotechnologies are promising, their safety is still tricky and this must be kept in mind.

CONCLUSION

We are not about to see a concrete application of nanomedicine in daily psychiatric practice. However, it seems essential that psychiatrists do not forsake this area of research the perspectives of which could be decisive in the field of mental illness.

Preparation and characterization of vinculin-targeted polymer-lipid nanoparticle as intracellular delivery vehicle

Intracellular delivery vehicles have been extensively investigated as these can serve as an effective tool in studying the cellular mechanism, by delivering functional protein to specific locations of the cells. In the current study, a polymer–lipid nanoparticle (PLN) system was developed as an intracellular delivery vehicle specifically targeting vinculin, a focal adhesion protein associated with cellular adhesive structures, such as focal adhesions and adherens junctions. The PLNs possessed an average size of 106 nm and had a positively charged surface. With a lower encapsulation efficiency 32% compared with poly(lactic-co-glycolic) acid (PLGA) nanoparticles (46%), the PLNs showed the sustained release profile of model drug BSA, while PLGA nanoparticles demonstrated an initial burst-release property. Cell-uptake experiments using mouse embryonic fibroblasts cultured in fibrin–fibronectin gels observed, under confocal microscope, that the anti-vinculin conjugated PLNs could successfully ship the cargo to the cytoplasm of fibroblasts, adhered to fibronectin–fibrin. With the use of cationic lipid, the unconjugated PLNs were shown to have high gene transfection efficiency. Furthermore, the unconjugated PLNs had nuclear-targeting capability in the absence of nuclear-localization signals. Therefore, the PLNs could be manipulated easily via different type of targeting ligands and could potentially be used as a powerful tool for cellular mechanism study, by delivering drugs to specific cellular organelles.

Review: magnetic resonance imaging techniques in ophthalmology

Imaging the eye with magnetic resonance imaging (MRI) has proved difficult due to the eye's propensity to move involuntarily over typical imaging timescales, obscuring the fine structure in the eye due to the resulting motion artifacts. However, advances in MRI technology help to mitigate such drawbacks, enabling the acquisition of high spatiotemporal resolution images with a variety of contrast mechanisms. This review aims to classify the MRI techniques used to date in clinical and preclinical ophthalmologic studies, describing the qualitative and quantitative information that may be extracted and how this may inform on ocular pathophysiology.

Unique diagnostic and therapeutic roles of porphyrins and phthalocyanines in photodynamic therapy, imaging and theranostics

Porphyrinic molecules have a unique theranostic role in disease therapy; they have been used to image, detect and treat different forms of diseased tissue including age-related macular degeneration and a number of different cancer types. Current focus is on the clinical imaging of tumour tissue; targeted delivery of photosensitisers and the potential of photosensitisers in multimodal biomedical theranostic nanoplatforms. The roles of porphyrinic molecules in imaging and pdt, along with research into improving their selective uptake in diseased tissue and their utility in theranostic applications are highlighted in this Review.

Tumor-targeting multi-functional nanoparticles for theragnosis: new paradigm for cancer therapy

Theragnostic nanoparticles (NPs) contain diagnostic and therapeutic functions in one integrated system, enabling diagnosis, therapy, and monitoring of therapeutic response at the same time. For diagnostic function, theragnostic NPs require the inclusion of noninvasive imaging modalities. Among them, optical imaging has various advantages including sensitivity, real-time and convenient use, and non-ionization safety, which make it the leading technique for theragnostic NPs. For therapeutic function, theragnostic NPs have been applied to chemotherapy, photodynamic therapy, siRNA therapy and photothermal therapy. In this review, we present a recent progress reported in the development and applications of theragnostic NPs for cancer therapy. More specifically, we will focus on theragnostic NPs related with optical imaging, highlighting promising strategies based on optical imaging techniques.

Essential parameters to consider for the characterization of optical imaging probes

The Molecular Imaging and Contrast Agents Database (MICAD) was launched in 2005 to promote the development and application of imaging and contrast agents (probes) to advance the field of molecular imaging. As of March 2012, there are approximately 1170 agents available in MICAD. Based on the modality used for imaging, the largest category of probes described in MICAD are those used for PET (41.6%), followed by agents used for single-photon emission computed tomography (30.3%), optical imaging (12.0%), MRI (9.3%), multimodality imaging (3.4%), ultrasound (2.4%) and x-ray/computed tomography (1.0%). This article is intended to be a guideline for new investigators and students who wish to characterize an optical imaging probe that will be used to perform in vivo molecular imaging studies. It is necessary, however, to ensure that these agents meet certain quality control parameters before they are used in various in vitro and in vivo applications.

Phase-shift, stimuli-responsive perfluorocarbon nanodroplets for drug delivery to cancer

This review focuses on phase-shift perfluorocarbon nanoemulsions whose action depends on an ultrasound-triggered phase shift from a liquid to gas state. For drug-loaded perfluorocarbon nanoemulsions, microbubbles are formed under the action of tumor-directed ultrasound and drug is released locally into tumor volume in this process. This review covers in detail mechanisms involved in the droplet-to-bubble transition as well as mechanisms of ultrasound-mediated drug delivery.

Transport of nanocarriers across gastrointestinal epithelial cells by a new transcellular route induced by targeting ICAM-1

Bioavailability of oral drugs, particularly large hydrophilic agents, is often limited by poor adhesion and transport across gastrointestinal (GI) epithelial cells. Drug delivery systems, such as sub-micrometer polymer carriers (nanocarriers, NCs) coupled to affinity moieties that target GI surface markers involved in transport, may improve this aspect. To explore this strategy, we coated 100-nm polymer particles with an antibody to ICAM-1 (a protein expressed on the GI epithelium and other tissues) and evaluated targeting, uptake, and transport in human GI epithelial cells. Fluorescence and electron microscopy, and radioisotope tracing revealed that anti-ICAM NCs specifically bound to cells in culture, were internalized via CAM-mediated endocytosis, trafficked by transcytosis across cell monolayers without disrupting the permeability barrier or cell viability, and enabled transepithelial transport of a model therapeutic enzyme (α-galactosidase, deficient in lysosomal Fabry disease). These results indicate that ICAM-1 targeting may provide delivery of therapeutics, such as enzymes, to and across the GI epithelium.

Advanced contrast nanoagents for photoacoustic molecular imaging, cytometry, blood test and photothermal theranostics

Various nanoparticles have raised significant interest over the past decades for their unique physical and optical properties and biological utilities. Here we summarize the vast applications of advanced nanoparticles with a focus on carbon nanotube (CNT)-based or CNT-catalyzed contrast agents for photoacoustic (PA) imaging, cytometry and theranostics applications based on the photothermal (PT) effect. We briefly review the safety and potential toxicity of the PA/PT contrast nanoagents, while showing how the physical properties as well as multiple biological coatings change their toxicity profiles and contrasts. We provide general guidelines needed for the validation of a new molecular imaging agent in living subjects, and exemplify these guidelines with single-walled CNTs targeted to α(v) β(3) , an integrin associated with tumor angiogenesis, and golden carbon nanotubes targeted to LYVE-1, endothelial lymphatic receptors. An extensive review of the potential applications of advanced contrast agents is provided, including imaging of static targets such as tumor angiogenesis receptors, in vivo cytometry of dynamic targets such as circulating tumor cells and nanoparticles in blood, lymph, bones and plants, methods to enhance the PA and PT effects with transient and stationary bubble conjugates, PT/PA Raman imaging and multispectral histology. Finally, theranostic applications are reviewed, including the nanophotothermolysis of individual tumor cells and bacteria with clustered nanoparticles, nanothrombolysis of blood clots, detection and purging metastasis in sentinel lymph nodes, spectral hole burning and multiplex therapy with ultrasharp rainbow nanoparticles.