Inflammation-targeted gold nanorods for intravascular photoacoustic imaging detection of matrix metalloproteinase-2 (MMP 2 ) in atherosclerotic plaques

Aggregation-induced emission luminescence for angiography and atherosclerotic diagnosis

Optical imaging technology has become increasingly recognized for its utility in diagnosing atherosclerosis thanks to advantages such as high spatial resolution, rapid data acquisition, lack of radiation exposure, cost-effectiveness, minimal invasiveness, and limited side effects. However, traditional luminogens employed in optical diagnostics are often troubled by aggregation-caused quenching (ACQ) effect, causing diagnostic errors in vivo. Since Professor Tang discovered the aggregation-induced emission (AIE) phenomenon, AIE luminogens (AIEgens) have been rapidly developing and are considered as the next-generation fluorescent contrast agents for angiography and atherosclerotic diagnosis. This mini review will outline the use of AIEgens in angiography and the diagnosis of atherosclerosis, exploring different imaging models, including second near-infrared, two/multi-photon, and photoacoustic imaging, and will provide a forward-looking perspective on their potential in atherosclerotic diagnosis.

Fluorescent probes for imaging: a focus on atherosclerosis

Atherosclerosis, as a chronic cardiovascular disease driven by inflammation, can lead to arterial stenosis and thrombosis, which seriously threatens human life and health. Achieving the timely monitoring of atherosclerosis is an important measure to reduce acute cardiovascular diseases. Compared with other imaging platforms, fluorescence imaging technology has the characteristics of excellent sensitivity, high spatiotemporal resolution and real-time imaging, which is very suitable for direct visualization of molecular processes and abnormalities of atherosclerosis. Recently, researchers have strived to design a variety of fluorescent probes, from single-mode fluorescent probes to fluorescent-combined dual/multimode probes, to enrich the imaging and detection of atherosclerosis. Therefore, this review aims to provide an overview of currently investigated fluorescent probes in the context of atherosclerosis, summarize relevant published studies showing applications of different types of fluorescent probes in the early-stage and other stages to detect atherosclerosis, give effective biological targets and discuss the latest progress and some limitations. Finally, some insights are provided for the development of a new generation of more accurate and efficient fluorescent probes.

A review of recent advances in the use of complex metal nanostructures for biomedical applications from diagnosis to treatment

Complex metal nanostructures represent an exceptional category of materials characterized by distinct morphologies and physicochemical properties. Nanostructures with shape anisotropies, such as nanorods, nanostars, nanocages, and nanoprisms, are particularly appealing due to their tunable surface plasmon resonances, controllable surface chemistries, and effective targeting capabilities. These complex nanostructures can absorb light in the near-infrared, enabling noteworthy applications in nanomedicine, molecular imaging, and biology. The engineering of targeting abilities through surface modifications involving ligands, antibodies, peptides, and other agents potentiates their effects. Recent years have witnessed the development of innovative structures with diverse compositions, expanding their applications in biomedicine. These applications encompass targeted imaging, surface-enhanced Raman spectroscopy, near-infrared II imaging, catalytic therapy, photothermal therapy, and cancer treatment. This review seeks to provide the nanomedicine community with a thorough and informative overview of the evolving landscape of complex metal nanoparticle research, with a specific emphasis on their roles in imaging, cancer therapy, infectious diseases, and biofilm treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Diagnostic Nanodevices.

Detection and Imaging of Active Substances in Early Atherosclerotic Lesions Using Fluorescent Probes

Atherosclerosis (AS) is a vascular disease caused by chronic inflammation and lipids that is the main cause of myocardial infarction, stroke and other cardiovascular diseases. Atherosclerosis is often difficult to detect in its early stages due to the absence of clinically significant vascular stenosis. This is not conducive to early intervention or treatment of the disease. Over the past decade, researchers have developed various imaging methods for the detection and imaging of atherosclerosis. At the same time, more and more biomarkers are being found that can be used as targets for detecting atherosclerosis. Therefore, the development of a variety of imaging methods and a variety of targeted imaging probes is an important project to achieve early assessment and treatment of atherosclerosis. This paper provides a comprehensive review of the optical probes used to detect and target atherosclerosis imaging in recent years, and describes the current challenges and future development directions.

Atherosclerosis treatment with nanoagent: potential targets, stimulus signals and drug delivery mechanisms

Cardiovascular disease (CVDs) is the first killer of human health, and it caused up at least 31% of global deaths. Atherosclerosis is one of the main reasons caused CVDs. Oral drug therapy with statins and other lipid-regulating drugs is the conventional treatment strategies for atherosclerosis. However, conventional therapeutic strategies are constrained by low drug utilization and non-target organ injury problems. Micro-nano materials, including particles, liposomes, micelles and bubbles, have been developed as the revolutionized tools for CVDs detection and drug delivery, specifically atherosclerotic targeting treatment. Furthermore, the micro-nano materials also could be designed to intelligently and responsive targeting drug delivering, and then become a promising tool to achieve atherosclerosis precision treatment. This work reviewed the advances in atherosclerosis nanotherapy, including the materials carriers, target sites, responsive model and treatment results. These nanoagents precisely delivery the therapeutic agents to the target atherosclerosis sites, and intelligent and precise release of drugs, which could minimize the potential adverse effects and be more effective in atherosclerosis lesion.

Intravascular Imaging of Atherosclerosis by Using Engineered Nanoparticles

Atherosclerosis is a leading cause of morbidity and mortality, and high-risk atherosclerotic plaques can result in myocardial infarction, stroke, and/or sudden death. Various imaging and sensing techniques (e.g., ultrasound, optical coherence tomography, fluorescence, photoacoustic) have been developed for scanning inside blood vessels to provide accurate detection of high-risk atherosclerotic plaques. Nanoparticles have been utilized in intravascular imaging to enable targeted detection of high-risk plaques, to enhance image contrast, and in some applications to also provide therapeutic functions of atherosclerosis. In this paper, we review the recent progress on developing nanoparticles for intravascular imaging of atherosclerosis. We discuss the basic nanoparticle design principles, imaging modalities and instrumentations, and common targets for atherosclerosis. The review is concluded and highlighted with discussions on challenges and opportunities for bringing nanoparticles into in vivo (pre)clinical intravascular applications.

Targeted Imaging in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease involved in plaque rupture, stroke, thrombosis, and heart attack (myocardial infarction), which is a leading cause of sudden cardiovascular events. In the past decades, various imaging strategies have been designed and employed for the diagnosis of atherosclerosis. Targeted imaging can accurately distinguish pathological tissues from normal tissues and reliably reveal biological information in the occurrence and development of atherosclerosis. By taking advantage of versatile imaging techniques, rationally designed imaging probes targeting biomarkers overexpressed in plaque microenvironments and targeting activated cells by modifying specific ligands accumulated in lesion regions have attracted increasing attention. This Perspective elucidates comprehensively the targeted imaging strategies, current challenges, and future development directions for precise identification and diagnosis of atherosclerosis, which is beneficial to better understand the physiological and pathological progression and exploit novel imaging strategies.

Looking deep inside tissue with photoacoustic molecular probes: a review

Significance

Deep tissue noninvasive high-resolution imaging with light is challenging due to the high degree of light absorption and scattering in biological tissue. Photoacoustic imaging (PAI) can overcome some of the challenges of pure optical or ultrasound imaging to provide high-resolution deep tissue imaging. However, label-free PAI signals from light absorbing chromophores within the tissue are nonspecific. The use of exogeneous contrast agents (probes) not only enhances the imaging contrast (and imaging depth) but also increases the specificity of PAI by binding only to targeted molecules and often providing signals distinct from the background.

Aim

We aim to review the current development and future progression of photoacoustic molecular probes/contrast agents.

Approach

First, PAI and the need for using contrast agents are briefly introduced. Then, the recent development of contrast agents in terms of materials used to construct them is discussed. Then, various probes are discussed based on targeting mechanisms, in vivo molecular imaging applications, multimodal uses, and use in theranostic applications.

Results

Material combinations are being used to develop highly specific contrast agents. In addition to passive accumulation, probes utilizing activation mechanisms show promise for greater controllability. Several probes also enable concurrent multimodal use with fluorescence, ultrasound, Raman, magnetic resonance imaging, and computed tomography. Finally, targeted probes are also shown to aid localized and molecularly specific photo-induced therapy.

Conclusions

The development of contrast agents provides a promising prospect for increased contrast, higher imaging depth, and molecularly specific information. Of note are agents that allow for controlled activation, explore other optical windows, and enable multimodal use to overcome some of the shortcomings of label-free PAI.

Targeting the Microenvironment of Vulnerable Atherosclerotic Plaques: An Emerging Diagnosis and Therapy Strategy for Atherosclerosis

Atherosclerosis is considered one of the primary causes of cardiovascular diseases (CVDs). Unpredictable rupture of the vulnerable atherosclerotic plaques triggers adverse cardiovascular events such as acute myocardial syndrome and even sudden cardiac death. Therefore, assessing the vulnerability of atherosclerotic plaques and early intervention are of significance in reducing CVD mortality. Nanomedicine possesses tremendous advantages in achieving the integration of the diagnosis and therapy of atherosclerotic plaques because of its magnetic, optical, thermal, and catalytic properties. Based on the pathological characteristics of vulnerable plaques, stimuli-responsive nanoplatforms and surface-functionalized nanoagents are designed and have drawn great attention for accomplishing the precise imaging and treatment of vulnerable atherosclerotic plaques due to their superior properties, such as high bioavailability, lesion-targeting specificity, on-demand cargo release, and low off-target damage. Here, the characteristics of vulnerable plaques are generalized, and some targeted strategies for boosting the accuracy of plaque vulnerability evaluation by imaging and the efficacy of plaque stabilization therapy (including antioxidant therapy, macrophage depletion therapy, regulation of lipid metabolism therapy, anti-inflammation therapy, etc.) are systematically summarized. In addition, existing challenges and prospects in this field are discussed, and it is believed to provide new thinking for the diagnosis and treatment of CVDs in the near future.

Nanotechnology for cardiovascular diseases

Cardiovascular diseases have become the major killers in today's world, among which coronary artery diseases (CADs) make the greatest contributions to morbidity and mortality. Although state-of-the-art technologies have increased our knowledge of the cardiovascular system, the current diagnosis and treatment modalities for CADs still have limitations. As an emerging cross-disciplinary approach, nanotechnology has shown great potential for clinical use. In this review, recent advances in nanotechnology in the diagnosis of CADs will first be elucidated. Both the sensitivity and specificity of biosensors for biomarker detection and molecular imaging strategies, such as magnetic resonance imaging, optical imaging, nuclear scintigraphy, and multimodal imaging strategies, have been greatly increased with the assistance of nanomaterials. Second, various nanomaterials, such as liposomes, polymers (PLGA), inorganic nanoparticles (AuNPs, MnO2, etc.), natural nanoparticles (HDL, HA), and biomimetic nanoparticles (cell-membrane coating) will be discussed as engineered as drug (chemicals, proteins, peptides, and nucleic acids) carriers targeting pathological sites based on their optimal physicochemical properties and surface modification potential. Finally, some of these nanomaterials themselves are regarded as pharmaceuticals for the treatment of atherosclerosis because of their intrinsic antioxidative/anti-inflammatory and photoelectric/photothermal characteristics in a complex plaque microenvironment. In summary, novel nanotechnology-based research in the process of clinical transformation could continue to expand the horizon of nanoscale technologies in the diagnosis and therapy of CADs in the foreseeable future.

Gold nanostructures: synthesis, properties, and neurological applications

Recent advances in technology are expected to increase our current understanding of neuroscience. Nanotechnology and nanomaterials can alter and control neural functionality in both in vitro and in vivo experimental setups. The intersection between neuroscience and nanoscience may generate long-term neural interfaces adapted at the molecular level. Owing to their intrinsic physicochemical characteristics, gold nanostructures (GNSs) have received much attention in neuroscience, especially for combined diagnostic and therapeutic (theragnostic) purposes. GNSs have been successfully employed to stimulate and monitor neurophysiological signals. Hence, GNSs could provide a promising solution for the regeneration and recovery of neural tissue, novel neuroprotective strategies, and integrated implantable materials. This review covers the broad range of neurological applications of GNS-based materials to improve clinical diagnosis and therapy. Sub-topics include neurotoxicity, targeted delivery of therapeutics to the central nervous system (CNS), neurochemical sensing, neuromodulation, neuroimaging, neurotherapy, tissue engineering, and neural regeneration. It focuses on core concepts of GNSs in neurology, to circumvent the limitations and significant obstacles of innovative approaches in neurobiology and neurochemistry, including theragnostics. We will discuss recent advances in the use of GNSs to overcome current bottlenecks and tackle technical and conceptual challenges.

Advanced Ultrasound and Photoacoustic Imaging in Cardiology

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. An effective management and treatment of CVDs highly relies on accurate diagnosis of the disease. As the most common imaging technique for clinical diagnosis of the CVDs, US imaging has been intensively explored. Especially with the introduction of deep learning (DL) techniques, US imaging has advanced tremendously in recent years. Photoacoustic imaging (PAI) is one of the most promising new imaging methods in addition to the existing clinical imaging methods. It can characterize different tissue compositions based on optical absorption contrast and thus can assess the functionality of the tissue. This paper reviews some major technological developments in both US (combined with deep learning techniques) and PA imaging in the application of diagnosis of CVDs.

Enzyme-activated probes in optical imaging: a focus on atherosclerosis

Enzyme-activated probes enable complex biological processes to be studied in real-time. A wide range of enzymes are modulated in diseases, including cancer, inflammatory diseases and cardiovascular disease, and have the potential to act as vital diagnostic and prognostic biomarkers to monitor and report on disease progression. In this perspective article, we discuss suitable design characteristics of enzyme-activated fluorescent probes for ex vivo and in vivo optical imaging applications. With a particular focus on atherosclerosis imaging, we highlight recent approaches to report on the activity of cathepsins (K and B), matrix metalloproteinases (MMP-2 and MMP-9), thrombin, heme oxygenase-1 (HO-1) and myeloperoxidase (MPO).

Biomimetic Glucan Particles with Aggregation-Induced Emission Characteristics for Noninvasive Monitoring of Transplant Immune Response

Real-time monitoring of post-transplant immune response is critical to prolong the survival of grafts. The current gold standard for assessing the immune response to graft is biopsy. However, such a method is invasive and prone to false negative results due to limited tissue size available and the heterogeneity of the rejection site. Herein, we report biomimetic glucan particles with aggregation-induced emission (AIE) characteristics (HBTTPEP/GPs) for real-time noninvasive monitoring of post-transplant immune response. We have found that the positively charged near-infrared AIEgens can effectively aggregate in the confined space of glucan particles (GPs), thereby turning on the fluorescence emission. HBTTPEP/GPs can track macrophages for 7 days without hampering the bioactivity. Oral administration of HBTTPEP/GPs can specially target macrophages by mimicking yeast, which then migrate to the transplant rejection site. The fluorescence emitted from HBTTPEP/GPs correlated well with the infiltration of macrophages and the degree of allograft rejection. Furthermore, a single oral HBTTPEP/GPs dose can dynamically evaluate the therapeutic response to immunosuppressive therapy. Consequently, the biomimetic AIE-active glucan particles can be developed as a promising probe for immune-monitoring in solid organ transplantation.

Inflammatory microenvironment-targeted nanotherapies

Inflammatory microenvironments (IMEs) are common pathological characteristics and drive the development of multiple chronic diseases. Thus, IME-targeted therapies exhibit potential for the treatment of inflammatory diseases. Nanoplatforms have significant advantages in improving the efficiency of anti-inflammatory treatments. Owing to their improved therapeutic effects and reduced side effects, IME-targeted nanotherapies have recently drawn interest from the research community. This review introduces IMEs and discusses the application of IME-targeted nanotherapies for inflammatory diseases. The development of rational targeting strategies tailored to IMEs in damaged tissues can help promote therapies for chronic diseases.

Imaging Inflammation - From Whole Body Imaging to Cellular Resolution

Imaging techniques have evolved impressively lately, allowing whole new concepts like multimodal imaging, personal medicine, theranostic therapies, and molecular imaging to increase general awareness of possiblities of imaging to medicine field. Here, we have collected the selected (3D) imaging modalities and evaluated the recent findings on preclinical and clinical inflammation imaging. The focus has been on the feasibility of imaging to aid in inflammation precision medicine, and the key challenges and opportunities of the imaging modalities are presented. Some examples of the current usage in clinics/close to clinics have been brought out as an example. This review evaluates the future prospects of the imaging technologies for clinical applications in precision medicine from the pre-clinical development point of view.

New directions of activity-based sensing for in vivo NIR imaging

In vivo imaging is a powerful approach to study biological processes. Beyond cellular methods, in vivo studies allow for biological stimuli (small molecules or proteins) to be studied in their native environment. This has the potential to aid in the discovery of new biology and guide the development of diagnostics and therapies for diseases. To ensure selectivity and an observable readout, the probe development field is shifting towards activity-based sensing (ABS) approaches and near-infrared (NIR) imaging modalities. This perspective will highlight recent in vivo ABS applications that utilize NIR imaging platforms.

Recent advances in molecular imaging of atherosclerotic plaques and thrombosis

As the complications of atherosclerosis such as myocardial infarction and stroke are still one of the leading causes of mortality worldwide, the development of new diagnostic tools for the early detection of plaque instability and thrombosis is urgently needed. Advanced molecular imaging probes based on functional nanomaterials in combination with cutting edge imaging techniques are now paving the way for novel and unique approaches to monitor the inflammatory progress in atherosclerosis. This review focuses on the development of various molecular probes for the diagnosis of plaques and thrombosis in atherosclerosis, along with perspectives of their diagnostic applications in cardiovascular diseases. Specifically, we summarize the biological targets that can be used for atherosclerosis and thrombosis imaging. Then we describe the emerging molecular imaging techniques based on the utilization of engineered nanoprobes together with their challenges in clinical translation.

Photoacoustic Imaging in Tissue Engineering and Regenerative Medicine

Several imaging modalities are available for investigation of the morphological, functional, and molecular features of engineered tissues in small animal models. While research in tissue engineering and regenerative medicine (TERM) would benefit from a comprehensive longitudinal analysis of new strategies, researchers have not always applied the most advanced methods. Photoacoustic imaging (PAI) is a rapidly emerging modality that has received significant attention due to its ability to exploit the strong endogenous contrast of optical methods with the high spatial resolution of ultrasound methods. Exogenous contrast agents can also be used in PAI for targeted imaging. Applications of PAI relevant to TERM include stem cell tracking, longitudinal monitoring of scaffolds in vivo, and evaluation of vascularization. In addition, the emerging capabilities of PAI applied to the detection and monitoring of cancer and other inflammatory diseases could be exploited by tissue engineers. This article provides an overview of the operating principles of PAI and its broad potential for application in TERM. Impact statement Photoacoustic imaging, a new hybrid imaging technique, has demonstrated high potential in the clinical diagnostic applications. The optical and acoustic aspect of the photoacoustic imaging system works in harmony to provide better resolution at greater tissue depth. Label-free imaging of vasculature with this imaging can be used to track and monitor disease, as well as the therapeutic progression of treatment. Photoacoustic imaging has been utilized in tissue engineering to some extent; however, the full benefit of this technique is yet to be explored. The increasing availability of commercial photoacoustic systems will make application as an imaging tool for tissue engineering application more feasible. This review first provides a brief description of photoacoustic imaging and summarizes its current and potential application in tissue engineering.

Photoacoustic imaging for guidance of interventions in cardiovascular medicine

Imaging guidance is paramount to procedural success in minimally invasive interventions. Catheter-based therapies are the standard of care in the treatment of many cardiac disorders, including coronary artery disease, structural heart disease and electrophysiological conditions. Many of these diseases are caused by, or effect, a change in vasculature or cardiac tissue composition, which can potentially be detected by photoacoustic imaging. This review summarizes the state of the art in photoacoustic imaging approaches that have been proposed for intervention guidance in cardiovascular care. All of these techniques are currently in the preclinical phase. We will conclude with an outlook towards clinical applications.

Laser threshold and cell damage mechanism for intravascular photoacoustic imaging

OBJECTIVES

Intravascular photoacoustic (IVPA) imaging is being developed to image atherosclerotic plaques, a leading cause of morbidity and mortality in the United States. However, the safety of this imaging modality, which requires repeated irradiation with short laser pulses, has not yet been investigated. This study has two objectives. First, determine in vitro the limit of cumulative fluence that can be applied to cells before death at IVPA relevant wavelengths. Second, evaluate if high single pulse fluences are a potential cause of cell death during IVPA imaging.

MATERIALS AND METHODS

Experiments were conducted using endothelial cells, macrophages, and smooth muscle cells. The cumulative fluence experiments were conducted at 1064 and 1197 nm, using a high pulse repetition frequency laser. Cells were irradiated with a wide range of cumulative fluences and evaluated for cell death. The thresholds for death were compared to the maximum expected clinical cumulative fluence. To evaluate the effect of single pulse fluences, cells were irradiated at 1064, 1210, and 1720 nm. Light was delivered at a range of pulse energies to emulate the fluences that cells would be exposed to during clinical IVPA imaging.

RESULTS

At 1064 nm, all three cell types remained viable at cumulative fluences above the maximum expected clinical cumulative fluence, which is calculated based on common IVPA imaging protocols. At 1197 nm, cells were viable near or just below the maximum expected clinical cumulative fluence, with some cell type to cell type variation. All three cell types remained viable after irradiation with high single pulse fluences at all three wavelengths.

CONCLUSION

The cumulative fluence experiments indicate that safety considerations are likely to put constraints on the amount of irradiation that can be used in IVPA imaging protocols. However, this study also indicates that it will be possible to use IVPA imaging safely, since cumulative fluences could be reduced by as much as two orders of magnitude below the maximum expected clinical cumulative fluence by varying the imaging protocol, albeit at the expense of image quality. The single pulse fluence experiments indicate that cell death from single pulse fluence is not likely during IVPA imaging. Thus, future studies should focus on heat accumulation as the likely mechanism of tissue damage. Lasers Surg. Med. 51:466-474, 2019. © 2018 Wiley Periodicals, Inc.

Atherosclerosis Treatment with Stimuli-Responsive Nanoagents: Recent Advances and Future Perspectives

Atherosclerosis is the root of approximately one-third of global mortalities. Nanotechnology exhibits splendid prospects to combat atherosclerosis at the molecular level by engineering smart nanoagents with versatile functionalizations. Significant advances in nanoengineering enable nanoagents to autonomously navigate in the bloodstream, escape from biological barriers, and assemble with their nanocohort at the targeted lesion. The assembly of nanoagents with endogenous and exogenous stimuli breaks down their shells, facilitates intracellular delivery, releases their cargo to kill the corrupt cells, and gives imaging reports. All these improvements pave the way toward personalized medicine for atherosclerosis. This review systematically summarizes the recent advances in stimuli-responsive nanoagents for atherosclerosis management and its progress in clinical trials.

A Photoacoustic Probe for the Imaging of Tumor Apoptosis by Caspase-Mediated Macrocyclization and Self-Assembly

Photoacoustic (PA) imaging shows promise in the sensitive detection of caspase-3 activated in early tumor apoptosis in response to chemotherapy; smart PA probes are thus in high demand. Herein, we report the first smart PA probe (1-RGD) responsive to caspase-3, enabling real-time and high-resolution imaging of tumor apoptosis. 1-RGD is designed to leverage the synergetic effect of active delivery and caspase-3 activation. It is selectively recognized by active caspase-3 to trigger peptide substrate cleavage and biocompatible macrocyclization-mediated self-assembly, leading to an amplified PA imaging signal and prolonged retention in apoptotic tumor cells. Strong, high-resolution PA images are obtained in chemotherapy-induced apoptotic tumors in living mice after intravenous administration with 1-RGD, facilitating sensitive reporting of caspase-3 activity and distribution within tumor tissues.

Cationic poly-l-lysine-encapsulated melanin nanoparticles as efficient photoacoustic agents targeting to glycosaminoglycans for the early diagnosis of articular cartilage degeneration in osteoarthritis

Cartilage degeneration is the hallmark of osteoarthritis (OA) and its early diagnosis is essential for effective cartilage repair. However, until now, there was still a lack of imaging modalities that can accurately detect and evaluate cartilage degeneration in its early stage. Herein, we introduce endogenous melanin nanoparticles (MNPs) encapsulated by poly-l-lysine (PLL) as positively charged contrast agents for the accurate photoacoustic (PA) imaging of cartilage degeneration through its strong electrostatic interaction with anionic glycosaminoglycans (GAGs) in the cartilage. PLL-MNPs presented high PA intensity, photostability and biocompatibility. In vitro PAI studies showed that PLL-MNPs with a zeta potential of +32.5 ± 9.3 mV had more cartilage uptake and longer retention time than anionic MNPs, and generated a positive relationship with the GAG content in the cartilage. After administration via intra-articular injection in living mouse models, PLL-MNPs exhibited about a two-fold stronger PA signal in a normal joint (with high GAG content) than an OA joint (with low GAG content). Furthermore, the obtained PAI results provided accurate information of the GAG content distribution in the OA knee joint. Consequently, by detecting and analyzing the changes of the GAG content in OA cartilage using PAI, we can clearly distinguish early OA from late OA and monitor the therapeutic efficacy in OA after drug treatment. All PAI results were examined histologically.

Noninvasive detection of acute cerebral hypoxia and subsequent matrix-metalloproteinase activity in a mouse model of cerebral ischemia using multispectral-optoacoustic-tomography

Oxygen metabolism and matrix metalloproteinases (MMPs) play important roles in the pathophysiology of cerebral ischemia. Using multispectral optoacoustic tomography (MSOT) imaging, we visualized in vivo changes in cerebral tissue oxygenation during 1 h of transient middle cerebral artery occlusion (tMCAO) and at 48 h after reperfusion together with MMP activity using an MMP-activatable probe. The deoxyhemoglobin, oxyhemoglobin, and MMP signals were coregistered with structural magnetic resonance imaging data. The ipsi-/contralateral ratio of tissue oxygen saturation ([Formula: see text]) was significantly reduced during 1 h of tMCAO and recovered after 48 h of reperfusion in tMCAO compared with sham-operated mice ([Formula: see text] to 10 per group). A higher ipsi-/contralateral MMP signal ratio was detected at 48 h after reperfusion in the lesioned brain regions of tMCAO compared with the sham-operated animal ([Formula: see text] to 6 per group). Ex vivo near-infrared fluorescence imaging of MMP signal in brain slices was used to validate in vivo MSOT measurements. In conclusion, noninvasive MSOT imaging can provide visualization of hemodynamic alterations and MMP activity in a mouse model of cerebral ischemia.

The Influence of Differently Shaped Gold Nanoparticles Functionalized with NIPAM-Based Hydrogels on the Release of Cytochrome C

Here, we report the synthesis and functionalization of five different shapes of Au nanoparticles (NPs), namely nanorods, tetrahexahedral, bipyramids, nanomakura, and spheres with PEG and poly (N-isopropylacrylamide)-acrylic acid (pNIPAm-AAc) hydrogels. The anisotropic NPs are synthesized using seed-mediated growth in the presence of silver. The NPs have been characterized using Dynamic Light Scattering (DLS), zeta potential measurements, UV-Visible spectrophotometry (UV-Vis), and Scanning Transmission Electron Microscopy (S(T)EM). Cyt C was loaded into the PEG-hydrogel-coated AuNPs using a modified breathing-in method. Loading efficiencies (up to 80%), dependent on particle geometry, concentration, and hydrogel content, were obtained. Release experiments conducted at high temperature (40 °C) and acidic pH (3) showed higher release for larger sizes of PEG-hydrogel-coated AuNPs, with temporal transition from spherical to thin film release geometry. AuNP shape, size, number density, and hydrogel content are found to influence the loading as well as release kinetics of Cyt C from these systems.

Crocus sativus L. aqueous extract reduces atherogenesis, increases atherosclerotic plaque stability and improves glucose control in diabetic atherosclerotic animals

BACKGROUND AND AIMS

We aimed to evaluate a possible atheroprotective effect of saffron aqueous extract (SFE), and its potential anti-inflammatory mechanisms, in apoE knockout (ApoE^-/-) mice.

METHODS

Fifty male, ApoE^-/- mice, fed a high-fat diet (HFD) for 12 weeks, were randomized into 5 groups: (1) baseline group, euthanatized, without intervention, (2) three saffron groups, receiving HFD and 30,60,90 mg/kg/day of SFE, respectively, for four weeks, per os through gavage, after reconstitution in water for injection (WFI), (3) control group (COG), receiving daily HFD and the same volume of WFI (four weeks). After blood sampling and euthanasia, aortic roots were excised and analyzed for gene expression and/or percentage of aortic stenosis, relative content of macrophages, smooth muscle cells (SMCs), connective tissue, tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinases-2,-3,-9 (MMP-2,-3,-9) and their inhibitor (TIMP-2) and IL-6. SFE doses were determined by a pilot serum pharmacokinetic study in C57BL/6J wild-type mice.

RESULTS

SFE did not affect body weight and total cholesterol levels (p > 0.05), while high SFE dose significantly ameliorated glucose and triglycerides profiles compared to other groups (p < 0.05). SFE considerably decreased aortic stenosis in a dose-dependent manner (p < 0.05). Furthermore, increasing SFE doses proportionally reduced macrophages content and increased within plaques content of collagen, elastin, and SMCs, promoting more stable plaque phenotype compared to COG (p < 0.05). Those effects seemed to be associated with a considerable reduction (>30%) in IL-6, TNF-α, MCP-1, MMP-2,-3,-9 (p < 0.05) and MMP-2/TIMP-2 ratio.

CONCLUSIONS

SFE exerted dose-dependent anti-atherosclerotic and plaque-stabilizing effects in Apo-E^-/- mice, probably mediated by a favorable modification of inflammatory mechanisms, which requires further investigation.

Real-time intravascular photoacoustic-ultrasound imaging of lipid-laden plaque in human coronary artery at 16 frames per second

Intravascular photoacoustic-ultrasound (IVPA-US) imaging is an emerging hybrid modality for the detection of lipid-laden plaques, as it provides simultaneous morphological and lipid-specific chemical information of an artery wall. Real-time imaging and display at video-rate speed are critical for clinical utility of the IVPA-US imaging technology. Here, we demonstrate a portable IVPA-US system capable of imaging at up to 25 frames per second in real-time display mode. This unprecedented imaging speed was achieved by concurrent innovations in excitation laser source, rotary joint assembly, 1 mm IVPA-US catheter size, differentiated A-line strategy, and real-time image processing and display algorithms. Spatial resolution, chemical specificity, and capability for imaging highly dynamic objects were evaluated by phantoms to characterize system performance. An imaging speed of 16 frames per second was determined to be adequate to suppress motion artifacts from cardiac pulsation for in vivo applications. The translational capability of this system for the detection of lipid-laden plaques was validated by ex vivo imaging of an atherosclerotic human coronary artery at 16 frames per second, which showed strong correlation to gold-standard histopathology. Thus, this high-speed IVPA-US imaging system presents significant advances in the translational intravascular and other endoscopic applications.

Evidence for the Involvement of Matrix-Degrading Metalloproteinases (MMPs) in Atherosclerosis

Atherosclerosis leads to blockage of arteries, culminating in myocardial infarction, and stroke. The involvement of matrix-degrading metalloproteinases (MMPs) in atherosclerosis is established and many studies have highlighted the importance of various MMPs in this process. MMPs were first implicated in atherosclerosis due to their ability to degrade extracellular matrix components, which can lead to increased plaque instability. However, more recent work has highlighted a multitude of roles for MMPs in addition to breakdown of extracellular matrix proteins. MMPs are now known to be involved in various stages of plaque progression: from initial macrophage infiltration to plaque rupture. This chapter summarizes the development and progression of atherosclerotic plaques and the contribution of MMPs. We provide data from human studies showing the effect of MMP polymorphisms and the expression of MMPs in both the atherosclerotic plaque and within plasma. We also discuss work in animal models of atherosclerosis that show the effect of gain or loss of function of MMPs. Together, the data provided from these studies illustrate that MMPs are ideal targets as both biomarkers and potential drug therapies for atherosclerosis.

Biomedical photoacoustics: fundamentals, instrumentation and perspectives on nanomedicine

Photoacoustic imaging (PAI) is an integrated biomedical imaging modality which combines the advantages of acoustic deep penetration and optical high sensitivity. It can provide functional and structural images with satisfactory resolution and contrast which could provide abundant pathological information for disease-oriented diagnosis. Therefore, it has found vast applications so far and become a powerful tool of precision nanomedicine. However, the investigation of PAI-based imaging nanomaterials is still in its infancy. This perspective article aims to summarize the developments in photoacoustic technologies and instrumentations in the past years, and more importantly, present a bright outlook for advanced PAI-based imaging nanomaterials as well as their emerging biomedical applications in nanomedicine. Current challenges and bottleneck issues have also been discussed and elucidated in this article to bring them to the attention of the readership.

Recent Advances in Photoacoustic Imaging for Deep-Tissue Biomedical Applications

Photoacoustic imaging (PAI), a novel imaging modality based on photoacoustic effect, shows great promise in biomedical applications. By converting pulsed laser excitation into ultrasonic emission, PAI combines the advantages of optical imaging and ultrasound imaging, which benefits rich contrast, high resolution and deep tissue penetration. In this paper, we introduced recent advances of contrast agents, applications, and signal enhancement strategies for PAI. The PA contrast agents were categorized by their components, mainly including inorganic and organic PA contrast agents. The applications of PAI were summarized as follows: deep tumor imaging, therapeutic responses monitoring, metabolic imaging, pH detection, enzyme detection, reactive oxygen species (ROS) detection, metal ions detection, and so on. The enhancement strategies of PA signals were highlighted. In the end, we elaborated on the challenges and provided perspectives of PAI for deep-tissue biomedical applications.