Assessment of Gold-Coated Iron Oxide Nanoparticles as Negative T2 Contrast Agent in Small Animal MRI Studies

Prospect of nanomaterials as antimicrobial and antiviral regimen

In recent years studies of nanomaterials have been explored in the field of microbiology due to the increasing evidence of antibiotic resistance. Nanomaterials could be inorganic or organic, and they may be synthesized from natural products from plant or animal origin. The therapeutic applications of nano-materials are wide, from diagnosis of disease to targeted delivery of drugs. Broad-spectrum antiviral and antimicrobial activities of nanoparticles are also well evident. The ratio of nanoparticles surface area to their volume is high and that allows them to be an advantageous vehicle of drugs in many respects. Effective uses of various materials for the synthesis of nanoparticles impart much specificity in them to meet the requirements of specific therapeutic strategies. The potential therapeutic use of nanoparticles and their mechanisms of action against infections from bacteria, fungi and viruses were the focus of this review. Further, their potential advantages, drawbacks, limitations and side effects are also included here. Researchers are characterizing the exposure pathways of nano-medicines that may cause serious toxicity to the subjects or the environment. Indeed, societal ethical issues in using nano-medicines pose a serious question to scientists beyond anything.

Indoleamine 2,3-dioxygenase 1 signaling orchestrates immune tolerance in Echinococcus multilocularis-infected mice

The cestode Echinococcus multilocularis larva infection causes lethal zoonotic alveolar echinococcosis (AE), a disease posing a great threat to the public health worldwide. This persistent hepatic tumor-like disease in AE patients has been largely attributed to aberrant T cell responses, of which Th1 responses are impeded, whilst Th2 and regulatory T cell responses are elevated, creating an immune tolerogenic microenvironment in the liver. However, the immune tolerance mechanisms are not fully understood. Dendritic cells (DCs) are key cellular components in facilitating immune tolerance in chronic diseases, including AE. Here, we demonstrate that indoleamine 2,3-dioxygenase 1-deficient (IDO1-/-) mice display less severe AE as compared to wild-type (WT) mice during the infection. Mechanistically, IDO1 prevents optimal T cells responses by programming DCs into a tolerogenic state. Specifically, IDO1 prevents the maturation and migration potential of DCs, as shown by the significantly enhanced expression of the antigen-presenting molecule (MHC II), costimulatory molecules (CD80 and CD86), and chemokine receptors (CXCR4 and CCR7) in infected IDO1-/- mice as compared to infected wild-type mice. More importantly, the tolerogenic phenotype of DCs is partly reverted in IDO1-/- mice, as indicated by enhanced activation, proliferation, and differentiation of both CD4+ and CD8+ - T cells upon infection with Echinococcus multilocularis, in comparison with WT mice. Interestingly, in absence of IDO1, CD4+ T cells are prone to differentiate to effector memory cells (CD44+CD62L-); in contrast, CD8+ T cells are highly biased to the central memory phenotype (CD44+CD62L+). Overall, these data are the first to demonstrate the essential role of IDO1 signaling in inducing immunosuppression in mice infected with Echinococcus multilocularis.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Monodisperse Gold Nanoparticles: A Review on Synthesis and Their Application in Modern Medicine

Gold nanoparticles (AuNPs) are becoming increasingly popular as drug carriers due to their unique properties such as size tenability, multivalency, low toxicity and biocompatibility. AuNPs have physical features that distinguish them from bulk materials, small molecules and other nanoscale particles. Their unique combination of characteristics is just now being fully realized in various biomedical applications. In this review, we focus on the research accomplishments and new opportunities in this field, and we describe the rising developments in the use of monodisperse AuNPs for diagnostic and therapeutic applications. This study addresses the key principles and the most recent published data, focusing on monodisperse AuNP synthesis, surface modifications, and future theranostic applications. Moving forward, we also consider the possible development of functionalized monodisperse AuNPs for theranostic applications based on these efforts. We anticipate that as research advances, flexible AuNPs will become a crucial platform for medical applications.

Treasure on the Earth—Gold Nanoparticles and Their Biomedical Applications

Recent advances in the synthesis of metal nanoparticles (NPs) have led to tremendous expansion of their potential applications in different fields, ranging from healthcare research to microelectronics and food packaging. Among the approaches for exploiting nanotechnology in medicine, gold nanomaterials in particular have been found as the most promising due to their unique advantages, such as in sensing, image enhancement, and as delivery agents. Although, the first scientific article on gold nanoparticles was presented in 1857 by Faraday, during the last few years, the progress in manufacturing these nanomaterials has taken an enormous step forward. Due to the nanoscale counterparts of gold, which exhibit distinct properties and functionality compared to bulk material, gold nanoparticles stand out, in particular, in therapy, imaging, detection, diagnostics, and precise drug delivery. This review summarizes the current state-of-the-art knowledge in terms of biomedical applications of gold nanoparticles. The application of AuNPs in the following aspects are discussed: (i) imaging and diagnosing of specific target; (ii) treatment and therapies using AuNPs; and (iii) drug delivery systems with gold nanomaterials as a carrier. Among the different approaches in medical imaging, here we either consider AuNPs as a contrast agent in computed tomography (CT), or as a particle used in optical imaging, instead of fluorophores. Moreover, their nontoxic feature, compared to the gadolinium-based contrast agents used in magnetic resonance imaging, are shown. The tunable size, shape, and functionality of gold nanoparticles make them great carriers for targeted delivery. Therefore, here, we summarize gold-based nanodrugs that are FDA approved. Finally, various approaches to treat the specific diseases using AuNPs are discussed, i.e., photothermal or photodynamic therapy, and immunotherapy.

Reconstruction of Preclinical PET Images via Chebyshev Polynomial Approximation of the Sinogram

Over the last decades, there has been an increasing interest in dedicated preclinical imaging modalities for research in biomedicine. Especially in the case of positron emission tomography (PET), reconstructed images provide useful information of the morphology and function of an internal organ. PET data, stored as sinograms, involve the Radon transform of the image under investigation. The analytical approach to PET image reconstruction incorporates the derivative of the Hilbert transform of the sinogram. In this direction, in the present work we present a novel numerical algorithm for the inversion of the Radon transform based on Chebyshev polynomials of the first kind. By employing these polynomials, the computation of the derivative of the Hilbert transform of the sinogram is significantly simplified. Extending the mathematical setting of previous research based on Chebyshev polynomials, we are able to efficiently apply our new Chebyshev inversion scheme for the case of analytic preclinical PET image reconstruction. We evaluated our reconstruction algorithm on projection data from a small-animal image quality (IQ) simulated phantom study, in accordance with the NEMA NU 4-2008 standards protocol. In particular, we quantified our reconstructions via the image quality metrics of percentage standard deviation, recovery coefficient, and spill-over ratio. The projection data employed were acquired for three different Poisson noise levels: 100% (NL1), 50% (NL2), and 20% (NL3) of the total counts, respectively. In the uniform region of the IQ phantom, Chebyshev reconstructions were consistently improved over filtered backprojection (FBP), in terms of percentage standard deviation (up to 29% lower, depending on the noise level). For all rods, we measured the contrast-to-noise-ratio, indicating an improvement of up to 68% depending on the noise level. In order to compare our reconstruction method with FBP, at equal noise levels, plots of recovery coefficient and spill-over ratio as functions of the percentage standard deviation were generated, after smoothing the NL3 reconstructions with three different Gaussian filters. When post-smoothing was applied, Chebyshev demonstrated recovery coefficient values up to 14% and 42% higher, for rods 1–3 mm and 4–5 mm, respectively, compared to FBP, depending on the smoothing sigma values. Our results indicate that our Chebyshev-based analytic reconstruction method may provide PET reconstructions that are comparable to FBP, thus yielding a good alternative to standard analytic preclinical PET reconstruction methods.

PEGylation of Metal Oxide Nanoparticles Modulates Neutrophil Extracellular Trap Formation

Novel metal oxide nanoparticle (NP) contrast agents may offer safety and functionality advantages over conventional gadolinium-based contrast agents (GBCAs) for cancer diagnosis by magnetic resonance imaging. However, little is known about the behavior of metal oxide NPs, or of their effect, upon coming into contact with the innate immune system. As neutrophils are the body's first line of defense, we sought to understand how manganese oxide and iron oxide NPs impact leukocyte functionality. Specifically, we evaluated whether contrast agents caused neutrophils to release web-like fibers of DNA known as neutrophil extracellular traps (NETs), which are known to enhance metastasis and thrombosis in cancer patients. Murine neutrophils were treated with GBCA, bare manganese oxide or iron oxide NPs, or poly(lactic-co-glycolic acid) (PLGA)-coated metal oxide NPs with different incorporated levels of poly(ethylene glycol) (PEG). Manganese oxide NPs elicited the highest NETosis rates and had enhanced neutrophil uptake properties compared to iron oxide NPs. Interestingly, NPs with low levels of PEGylation produced more NETs than those with higher PEGylation. Despite generating a low rate of NETosis, GBCA altered neutrophil cytokine expression more than NP treatments. This study is the first to investigate whether manganese oxide NPs and GBCAs modulate NETosis and reveals that contrast agents may have unintended off-target effects which warrant further investigation.

MR/NIRF Dual-Mode Imaging of αvβ3 Integrin-Overexpressing Tumors Using a Lipopeptide-Based Contrast Agent

Early diagnosis and noninvasive detection of hepatocellular carcinoma have profound clinical implications for treatment quality and improved prognosis. To obtain high-resolution macroscopic anatomical information and high-sensitivity microscopic optical signals to detect tumors, it is highly desirable to develop dual-mode magnetic resonance imaging (MRI) and near-infrared fluorescent (NIRF) probes. An MR/NIRF dual-mode targeted contrast agent was created by encapsulating cyclic arginine-glycine-aspartate (cRGD) and Cy5.5 in liposomes and characterized by the particle size distribution, cytotoxicity, targeting, and MRI relaxivity. The MR T2 intensity and fluorescence intensity were evaluated in the tumors, livers, and muscles after the injection of cRGD-Liposome-Cy5.5 and Liposome-Cy5.5 at different time points. The average size of cRGD-Liposome-Cy5.5 was 62.33 ± 4.648 nm. The transverse relaxivity (R2) values had a negative correlation with the concentration of molecular probes. The MR signal intensity was enhanced in tumors after the cRGD-Liposome-Cy5.5 injection and not enhanced in liver parenchyma and muscles at the same time. The fluorescence intensity was enhanced in tumors after cRGD-Liposome-Cy5.5 injection in the targeted group. cRGD -Liposome-Cy5.5 as an entirely organic T2-positive dual-mode MR/NIRF targeted contrast agent is therefore able to detect early-stage hepatocellular carcinoma by targeting integrin αvβ3, providing advantages for potential clinical utility and ease of clinical transformation.

Molecular Photoacoustic Imaging

Medicine has gone through several challenges to make it much more accurate and thus prolong the human being's life. A large part of this challenge is diseased, so early detection can help carry out treatment on time. There is a technology that allows detecting an abnormality within the body without using an invasive method. Ultrasound is a diagnostic test used to scan organs and tissues through sound waves. Although this technique has been widely used, the results are not desired because the images generated are not high resolution. On the other hand, X-rays are used because it presents an image with a much higher resolution than other techniques based on light waves or ultrasound; despite this, they are harmful to cells. In consequence of this problem, another method called molecular photoacoustic imaging has been implemented. This technique bridges the traditional depth limits of ballistic optical imaging and diffuse optical imaging's resolution limits, using the acoustic waves generated in response to laser light absorption, which has now shown potential for molecular imaging, allowing the visualization of biological processes in a non-invasive way. The purpose of this article is to give a critically scoped review of the physical, chemical, and biochemical characteristics of existing photoacoustic contrast agents, highlighting the pivotal applications and current challenges for molecular photoacoustic imaging.

Potential of a sonochemical approach to generate MRI-PPT theranostic agents for breast cancer

The production of nanomaterials integrating diagnostic and therapeutic roles within one nanoplatform is important for medical applications. Such theranostics nanoplatforms could provide information on imaging, accurate diagnosis and, at the same time, could eradicate cancer cells. Fe₃O₄@Au core@shell nanoparticles (Fe₃O₄@AuNPs) have gained broad attention due to their unique innovations in magnetic resonance imaging (MRI) and photothermal therapy (PTT). Seed-mediated growth procedures were used to produce the Fe₃O₄@AuNPs. In these processes, complicated surface modifications, resulted in unsatisfactory properties. This work used the ability of the sonochemical approach to synthesize highly efficient theranostics agent Fe₃O₄@AuNPs with a size of approximately 22 nm in 5 min. The inner core of Fe₃O₄ acts as an MRI agent, whereas the photothermal effect stands accomplished by near-infrared absorption of the gold shell (Au shell), which results in the eradication of cancer cells. We have shown that Fe₃O₄@AuNPs have great biocompatibility and no major cytotoxicity has been identified. Relaxivity value (r₂) of synthesized Fe₃O₄@Au NPs, measured at 233 mM^-1s^-1, is significantly higher than those reported previously. The as-synthesized NPs have shown substantial photothermal ablation ability on MCF-7 in vitro under near-infrared laser irradiation. Consequently, Fe₃O₄@AuNPs synthesized in this study have great potential as an ideal candidate for MR imaging and PTT.

Progress of Cancer Nanotechnology as Diagnostics, Therapeutics, and Theranostics Nanomedicine: Preclinical Promise and Translational Challenges

Early detection, right therapeutic intervention, and simultaneous effectiveness mapping are considered the critical factors in successful cancer therapy. Nevertheless, these factors experience the limitations of conventional cancer diagnostics and therapeutics delivery approaches. Along with providing the targeted therapeutics delivery, advances in nanomedicines have allowed the combination of therapy and diagnostics in a single system (called cancer theranostics). This paper discusses the progress in the pre-clinical and clinical development of therapeutics, diagnostics, and theranostics cancer nanomedicines. It has been well evident that compared to the overabundance of works that claimed success in pre-clinical studies, merely 15 and around 75 cancer nanomedicines are approved, and currently under clinical trials, respectively. Thus, we also brief the critical bottlenecks in the successful clinical translation of cancer nanomedicines.