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

Spectral Photon-Counting Computed Tomography: Technical Principles and Applications in the Assessment of Cardiovascular Diseases

Spectral Photon-Counting Computed Tomography (SPCCT) represents a groundbreaking advancement in X-ray imaging technology. The core innovation of SPCCT lies in its photon-counting detectors, which can count the exact number of incoming x-ray photons and individually measure their energy. The first part of this review summarizes the key elements of SPCCT technology, such as energy binning, energy weighting, and material decomposition. Its energy-discriminating ability represents the key to the increase in the contrast between different tissues, the elimination of the electronic noise, and the correction of beam-hardening artifacts. Material decomposition provides valuable insights into specific elements' composition, concentration, and distribution. The capability of SPCCT to operate in three or more energy regimes allows for the differentiation of several contrast agents, facilitating quantitative assessments of elements with specific energy thresholds within the diagnostic energy range. The second part of this review provides a brief overview of the applications of SPCCT in the assessment of various cardiovascular disease processes. SPCCT can support the study of myocardial blood perfusion and enable enhanced tissue characterization and the identification of contrast agents, in a manner that was previously unattainable.

Elucidating Iron Metabolism through Molecular Imaging

Iron is essential for many physiological processes, and the dysregulation of its metabolism is implicated in the pathogenesis of various diseases. Recent advances in iron metabolism research have revealed multiple complex pathways critical for maintaining iron homeostasis. Molecular imaging, an interdisciplinary imaging technique, has shown considerable promise in advancing research on iron metabolism. Here, we comprehensively review the multifaceted roles of iron at the cellular and systemic levels (along with the complex regulatory mechanisms of iron metabolism), elucidate appropriate imaging methods, and summarize their utility and fundamental principles in diagnosing and treating diseases related to iron metabolism. Utilizing molecular imaging technology to deeply understand the complexities of iron metabolism and its critical role in physiological and pathological processes offers new possibilities for early disease diagnosis, treatment monitoring, and the development of novel therapies. Despite technological limitations and the need to ensure the biological relevance and clinical applicability of imaging results, molecular imaging technology's potential to reveal the iron metabolic process is unparalleled, providing new insights into the link between iron metabolism abnormalities and various diseases.

Nanotechnology for brain tumor imaging and therapy based on π-conjugated materials: state-of-the-art advances and prospects

In contemporary biomedical research, the development of nanotechnology has brought forth numerous possibilities for brain tumor imaging and therapy. Among these, π-conjugated materials have garnered significant attention as a special class of nanomaterials in brain tumor-related studies. With their excellent optical and electronic properties, π-conjugated materials can be tailored in structure and nature to facilitate applications in multimodal imaging, nano-drug delivery, photothermal therapy, and other related fields. This review focuses on presenting the cutting-edge advances and application prospects of π-conjugated materials in brain tumor imaging and therapeutic nanotechnology.

Optimization of cobalt ferrite magnetic nanoparticle as a theranostic agent: MRI and hyperthermia

OBJECTIVE

Magnetic nanoparticles (MNPs) are considered a theranostic agent in MR imaging, playing an effective role in inducing magnetic hyperthermia. Since, high-performance magnetic theranostic agents are characterized by superparamagnetic behavior and high anisotropy, in this study, cobalt ferrite MNPs were optimized and investigated as a theranostic agent.

METHODS

CoFe2O4@Au@dextran particles were synthesized and characterized by DLS, HRTEM, SEM, XRD, FTIR, and VSM methods. After cytotoxicity evaluation, MR imaging parameters (r1, r2 and r2 / r1) were calculated for these nanostructures. Afterward, magnetic hyperthermia at the frequency of 425 kHz was applied to calculate specific loss power (SLP).

RESULTS

Formation of CoFe2O4@Au@dextran was confirmed by UV-Visible spectrophotometry. On the basis of the relaxometric and hyperthermia induction findings of nanostructures in all stages of synthesis, the CoFe2O4@Au@dextran could produce the highest parameters of r2 and r2/r1 and SLP with values ​​of 389.7, 51.2 mM-1 s-1, and 2449 W/g, respectively.

CONCLUSION

The formation of multi-core MNPs by dextran coating is expected to improve the magnetic properties of the nanostructure, leading to optimization of theranostic parameters, so that CoFe2O4@Au@dextran NPs can create contrast-enhanced images more than three times the clinical use and require less contrast agent, reducing side effects. Accordingly, CoFe2O4@Au@dextran can be introduced as a suitable theranostic nanostructure with optimal efficiency.

Structural parameters of nanoparticles affecting their toxicity for biomedical applications: a review

Rapidly growing interest in using nanoparticles (NPs) for biomedical applications has increased concerns about their safety and toxicity. In comparison with bulk materials, NPs are more chemically active and toxic due to the greater surface area and small size. Understanding the NPs' mechanism of toxicity, together with the factors influencing their behavior in biological environments, can help researchers to design NPs with reduced side effects and improved performance. After overviewing the classification and properties of NPs, this review article discusses their biomedical applications in molecular imaging and cell therapy, gene transfer, tissue engineering, targeted drug delivery, Anti-SARS-CoV-2 vaccines, cancer treatment, wound healing, and anti-bacterial applications. There are different mechanisms of toxicity of NPs, and their toxicity and behaviors depend on various factors, which are elaborated on in this article. More specifically, the mechanism of toxicity and their interactions with living components are discussed by considering the impact of different physiochemical parameters such as size, shape, structure, agglomeration state, surface charge, wettability, dose, and substance type. The toxicity of polymeric, silica-based, carbon-based, and metallic-based NPs (including plasmonic alloy NPs) have been considered separately.

[99mTc]-labeling and evaluation of a new linear peptide for imaging of glioblastoma as a αvβ3-positive tumor

PURPOSE

In this study, we designed a new linear 6-Hydrazinonicotinamide (HYNIC)-conjugated peptide (HYNIC-KRWrNM) (M-6) and labeled with technetium-99m for gamma imaging of glioblastoma as a α_vβ₃-positive tumor. We evaluated tumor targeting ability of this radio-peptide and compared with previous ^99mTc-labeled HYNIC-conjugated RGD analogue peptides.

PROCEDURES

One new linear peptide (HYNIC-KRWrNM) (M-6) was designed and labeled with technetium-99m in the presence of 2-[[1,3-dihydroxy-2-(hydroxymethyl) propan-2-yl] amino] acetic acid (Tricine)/Ethylenediamine-N,N'-diacetic acid (EDDA) as co-ligand system. Then, this ^99mTc-labeled peptide ([^99mTc]Tc-M-7) was evaluated for in vitro stability in saline and serum, specific binding assay, internalization, and binding affinity (K_d). In addition, we performed biodistribution study and planar imaging on nude mice bearing U87-MG xenograft as a α_vβ₃-positive tumor.

RESULTS

The radiochemical yield of [^99mTc]Tc-M-7 was obtained ˃95%. This ^99mTc-labeled peptide remained stable and intact in saline solution after 24 h incubation. In addition, metabolic stability of this ^99mTc-labeled peptide was obtained ˃60% after 4 h incubation in serum. The K_d value for [^99mTc]Tc-M-7 was obtained 5.2 ± 1.0 nM. Based on biodistribution results in nude mice bearing U87-MG xenograft, tumor/muscle activity ratio was 6.22 and decreased to 1.89 in blocking group at the same time point (4 h p.i.). The blocking experiment results also indicated that tumor uptake and kidney uptake were α_vβ₃-mediated. In comparison with previous HYNIC-conjugated RGD analogue peptides, kidneys had the highest uptake of this ^99mTc-labeled peptide (52.29 ± 11.48 at 1.5 h p.i. and 27.04 ± 0.66%ID/g at 4 h p.i.). Finally, similar to previous ^99mTc-labeled HYNIC-conjugated RGD analogue peptides, [^99mTc]Tc-M-7 showed acceptable tumor uptake after 4 h post-injection (based on ROI technique, target-to-background activity ratio = 3.80).

CONCLUSIONS

This small linear ^99mTc-labeled peptide, with high affinity to α_vβ₃ integrin, desirable water solubility, and cost efficient, demonstrates a potent tumor targeting ability as well as previous HYNIC-conjugated RGD analogue peptides. Hence, [^99mTc]Tc-M-7 can be of service to as a new candidate for early detection of α_vβ₃-positive tumors.

Modified Bismuth Nanoparticles: A New Targeted Nanoprobe for Computed Tomography Imaging of Cancer

OBJECTIVE

Recently, development of multifunctional contrast agent for effective targeted molecular computed tomography (CT) imaging of cancer cells stays a major problem. In this study, we explain the ability of Triptorelin peptide-targeted multifunctional bismuth nanoparticles (Bi2S3@ BSA-Triptorelin NPs) for molecular CT imaging.

MATERIALS AND METHODS

In this experimental study, the formed nanocomplex of Bi2S3@ BSA-Triptorelin NPs was characterized using different methods. The MTT cytotoxicity test was performed to determine the appropriate concentration of nanoparticles in the MCF-7 cells. The X-ray attenuation intensity and Contrast to Noise Ratio (CNR) of targeted and non-targeted nanoparticles were measured at the concentrations of 25, 50, and 75 μg/ml and X-ray tube voltages of 90, 120 and 140 kVp.

RESULTS

We showed that the formed Bi2S3@ BSA-Triptorelin NPs with a Bi core size of approximately ~8.6 nm are nontoxic in a given concentration (0-200 μg/ml). At 90, 120, and 140 tube potentials (kVp), the X-ray attenuation of targeted cells were 1.35, 1.36, and 1.33-times, respectively, more than non-targeted MCF-7cells at the concentration of 75 μg/ml. The CNR values at 90, 120, and 140 kVp tube potentials were 171.5, 153.8 and 146.3 c/ϭ, respectively.

CONCLUSION

These findings propose that the diagnostic nanocomplex of Bi2S3@ BSA-Triptorelin NPs can be applied as a good contrast medium for molecular CT techniques.

Challenges and opportunities in the development of metal-based anticancer theranostic agents

Around 10 million fatalities were recorded worldwide in 2020 due to cancer and statistical projections estimate the number to increase by 60% in 2040. With such a substantial rise in the global cancer burden, the disease will continue to impose a huge socio-economic burden on society. Currently, the most widely used clinical treatment modality is cytotoxic chemotherapy using platinum drugs which is used to treat variety of cancers. Despite its clinical success, critical challenges like resistance, off-target side effects and cancer variability often reduce its overall therapeutic efficiency. These challenges require faster diagnosis, simultaneous therapy and a more personalized approach toward cancer management. To this end, small-molecule ‘theranostic’ agents have presented a viable solution combining diagnosis and therapy into a single platform. In this review, we present a summary of recent efforts in the design and optimization of metal-based small-molecule ‘theranostic’ anticancer agents. Importantly, we highlight the advantages of a theranostic candidate over the purely therapeutic or diagnostic agent in terms of evaluation of its biological properties.

Nanotechnology as a Versatile Tool for 19F-MRI Agent's Formulation: A Glimpse into the Use of Perfluorinated and Fluorinated Compounds in Nanoparticles

Simultaneously being a non-radiative and non-invasive technique makes magnetic resonance imaging (MRI) one of the highly sought imaging techniques for the early diagnosis and treatment of diseases. Despite more than four decades of research on finding a suitable imaging agent from fluorine for clinical applications, it still lingers as a challenge to get the regulatory approval compared to its hydrogen counterpart. The pertinent hurdle is the simultaneous intrinsic hydrophobicity and lipophobicity of fluorine and its derivatives that make them insoluble in any liquids, strongly limiting their application in areas such as targeted delivery. A blossoming technique to circumvent the unfavorable physicochemical characteristics of perfluorocarbon compounds (PFCs) and guarantee a high local concentration of fluorine in the desired body part is to encapsulate them in nanosystems. In this review, we will be emphasizing different types of nanocarrier systems studied to encapsulate various PFCs and fluorinated compounds, headway to be applied as a contrast agent (CA) in fluorine-19 MRI (19F MRI). We would also scrutinize, especially from studies over the last decade, the different types of PFCs and their specific applications and limitations concerning the nanoparticle (NP) system used to encapsulate them. A critical evaluation for future opportunities would be speculated.

Electrospraying as a Technique for the Controlled Synthesis of Biocompatible PLGA@Ag2S and PLGA@Ag2S@SPION Nanocarriers with Drug Release Capability

Ag2S nanoparticles are near-infrared (NIR) probes providing emission in a specific spectral range (~1200 nm), and superparamagnetic iron oxide nanoparticles (SPION) are colloidal systems able to respond to an external magnetic field. A disadvantage of Ag2S NPs is the attenuated luminescent properties are reduced in aqueous media and human fluids. Concerning SPION, the main drawback is the generation of undesirable clusters that reduce particle stability. Here, we fabricate biocompatible hybrid nanosystems combining Ag2S NPs and SPION by the electrospraying technique for drug delivery purposes. These nanostructures are composed of poly(lactic-co-glycolic acid) (PLGA) as the polymeric matrix in connection with both Ag2S NPs and SPIONs. Initially, we fabricate a hybrid colloidal nanosystem composed of Ag2S NPs in connection with PLGA (PLGA@Ag2S) by three different routes, showing good photoluminescent (PL) properties with relatively high average decay times. Then, we incorporate SPIONs, obtaining a PLGA polymeric matrix containing both Ag2S NPs and SPION (PLGA@Ag2S@SPION). Interestingly, in this hybrid system, the location of Ag2S NPs and SPIONs depends on the synthesis route performed during electrospraying. After a detailed characterization, we demonstrate the encapsulation and release capabilities, obtaining the kinetic release using a model chemotherapeutic drug (maslinic acid). Finally, we perform in vitro cytotoxicity assays using drug-loaded hybrid systems against several tumor cell lines.

PET Use in Cancer Diagnosis, Treatment, and Prognosis

Tumorigenesis is a multistep process marked by variations in numerous metabolic pathways that affect cellular architectures and functions. Cancer cells reprogram their energy metabolism to enable several basic molecular functions, including membrane biosynthesis, receptor regulations, bioenergetics, and redox stress. In recent years, cancer diagnosis and treatment strategies have targeted these specific metabolic changes and the tumor's interactions with its microenvironment. Positron emission tomography (PET) captures all molecular alterations leading to abnormal function and cancer progression. As a result, the development of PET radiotracers increasingly focuses on irregular biological pathways or cells that overexpress receptors that have the potential to function as biomarkers for early diagnosis and treatment measurements as well as research. This chapter reviews both established and evolving PET radiotracers used to image tumor biology. We have also included a few advantages and disadvantages of the routinely used PET radiotracers in cancer imaging.

Targeted PET/MRI Imaging Super Probes: A Critical Review of Opportunities and Challenges

Recently, the demand for hybrid PET/MRI imaging techniques has increased significantly, which has sparked the investigation into new ways to simultaneously track multiple molecular targets and improve the localization and expression of biochemical markers. Multimodal imaging probes have recently emerged as powerful tools for improving the detection sensitivity and accuracy-both important factors in disease diagnosis and treatment; however, only a limited number of bimodal probes have been investigated in preclinical models. Herein, we briefly describe the strengths and limitations of PET and MRI modalities and highlight the need for the development of multimodal molecularly-targeted agents. We have tried to thoroughly summarize data on bimodal probes available on PubMed. Emphasis was placed on their design, safety profiles, pharmacokinetics, and clearance properties. The challenges in PET/MR probe development using a number of illustrative examples are also discussed, along with future research directions for these novel conjugates.

Synthesis and evaluation of 99mTc-DOTA-ARA-290 as potential SPECT tracer for targeting cardiac ischemic region

Objectives

Myocardial infarction caused by ischemia of heart tissue is the main reason for death worldwide; therefore, early detection can reduce mortality and treatment costs. Erythropoietin (EPO) has protection effects on ischemic tissue due to nonhematopoietic peptide (pHBSP; ARA-290) which is derived from the B-subunit of EPO.

Materials and Methods

We designed and synthesized a modified DOTA-(Lys-Dabcyl⁶, Phe⁷)-ARA-290 using Fmoc solid-phase peptide synthesis strategies. To improve serum stability, Fmoc-Lys-(Dabcyl)-OH as lipophilic amino acid was synthesized along with Fmoc-Phe-OH which then were substituted with Arg⁶ and Ala⁷, respectively; they were then investigated for the ability to detect ischemic cardiac imaging. DOTA-(Lys-Dabcyl⁶,Phe⁷)-ARA-290 was labeled with technetium 99m, and its radiochemical purity (RCP), stability in the presence of human serum and, specific bind to hypoxic H9c2 cells were evaluated. In vivo studies for biodistribution and SPECT scintigraphy were checked in a normal and cardiac ischemia rat model.

Results

Radiolabeling purity was obtained more than 96% by ITLC, and in vitro stability of the radiopeptide up to 6 hr was 85%. The binding of ^99mTc-ARA-290 to hypoxic cells was remarkably higher than normoxic cells (3 times higher than normoxic cells at 1 hr). Biodistribution and SPECT imaging on the cardiac ischemic model showed that radiopeptide considerably accumulated in the ischemic region (cardiac ischemic-to-lung rate = 3.65 ID/g % at 0.5 hr).

Conclusion

The results of studies, in vitro and in vivo, indicated that 99mTc-DOTA-(Lys-Dabcyl6,Phe7)-ARA-290 could be an appropriate candidate for early diagnosis of cardiac ischemia.

Selection and Characterization of Vimentin-Binding Aptamer Motifs for Ovarian Cancer

The application of aptamers in biomedicine is emerging as an essential technology in the field of cancer research. As small single-stranded DNA or RNA ligands with high specificity and low immunogenicity for their targets, aptamers provide many advantages in cancer therapeutics over protein-based molecules, such as antibodies. Vimentin is an intermediate filament protein that is overexpressed in endothelial cells of cancerous tissue. High expression levels of vimentin have been associated with increased capacity for migration and invasion of the tumor cells. We have selected and identified thioated aptamers with high specificity for vimentin using human ovarian cancer tissues. Tentative binding motifs were chosen for two vimentin aptamers based on predicted secondary structures. Each of these shorter, tentative binding motifs was synthesized, purified, and characterized via cell binding assays. Two vimentin binding motifs with high fidelity binding were selected and further characterized via cell and tissue binding assays, as well as flow cytometric analysis. The equilibrium binding constants of these small thioated aptamer constructs were also determined. Future applications for the vimentin binding aptamer motifs include conjugation of the aptamers to synthetic dyes for use in targeted imaging and therapy, and ultimately more detailed and precise monitoring of treatment response and tumor progression in ovarian pathology.

Biotherapeutic effect of cell-penetrating peptides against microbial agents: a review

Selective permeability of biological membranes represents a significant barrier to the delivery of therapeutic substances into both microorganisms and mammalian cells, restricting the access of drugs into intracellular pathogens. Cell-penetrating peptides usually 5-30 amino acids with the characteristic ability to penetrate biological membranes have emerged as promising antimicrobial agents for treating infections as well as an effective delivery modality for biological conjugates such as nucleic acids, drugs, vaccines, nanoparticles, and therapeutic antibodies. However, several factors such as antimicrobial resistance and poor drug delivery of the existing medications justify the urgent need for developing a new class of antimicrobials. Herein, we review cell-penetrating peptides (CPPs) used to treat microbial infections. Although these peptides are biologically active for infections, effective transduction into membranes and cargo transport, serum stability, and half-life must be improved for optimum functions and development of next-generation antimicrobial agents.

Versatile Types of Inorganic/Organic NIR-IIa/IIb Fluorophores: From Strategic Design toward Molecular Imaging and Theranostics

In vivo imaging in the second near-infrared window (NIR-II, 1000-1700 nm), which enables us to look deeply into living subjects, is producing marvelous opportunities for biomedical research and clinical applications. Very recently, there has been an upsurge of interdisciplinary studies focusing on developing versatile types of inorganic/organic fluorophores that can be used for noninvasive NIR-IIa/IIb imaging (NIR-IIa, 1300-1400 nm; NIR-IIb, 1500-1700 nm) with near-zero tissue autofluorescence and deeper tissue penetration. This review provides an overview of the reports published to date on the design, properties, molecular imaging, and theranostics of inorganic/organic NIR-IIa/IIb fluorophores. First, we summarize the design concepts of the up-to-date functional NIR-IIa/IIb biomaterials, in the order of single-walled carbon nanotubes (SWCNTs), quantum dots (QDs), rare-earth-doped nanoparticles (RENPs), and organic fluorophores (OFs). Then, these novel imaging modalities and versatile biomedical applications brought by these superior fluorescent properties are reviewed. Finally, challenges and perspectives for future clinical translation, aiming at boosting the clinical application progress of NIR-IIa and NIR-IIb imaging technology are highlighted.

Recent progress in sono-photodynamic cancer therapy: From developed new sensitizers to nanotechnology-based efficacy-enhancing strategies

Many sensitizers have not only photodynamic effects, but also sonodynamic effects. Therefore, the combination of sonodynamic therapy (SDT) and photodynamic therapy (PDT) using sensitizers for sono-photodynamic therapy (SPDT) provides alternative opportunities for clinical cancer therapy. Although significant advances have been made in synthesizing new sensitizers for SPDT, few of them are successfully applied in clinical settings. The anti-tumor effects of the sensitizers are restricted by the lack of tumor-targeting specificity, incapability in deep intratumoral delivery, and the deteriorating tumor microenvironment. The application of nanotechnology-based drug delivery systems (NDDSs) can solve the above shortcomings, thereby improving the SPDT efficacy. This review summarizes various sensitizers as sono/photosensitizers that can be further used in SPDT, and describes different strategies for enhancing tumor treatment by NDDSs, such as overcoming biological barriers, improving tumor-targeted delivery and intratumoral delivery, providing stimuli-responsive controlled-release characteristics, stimulating anti-tumor immunity, increasing oxygen supply, employing different therapeutic modalities, and combining diagnosis and treatment. The challenges and prospects for further development of intelligent sensitizers and translational NDDSs for SPDT are also discussed.

Next-Generation Molecular Imaging of Thyroid Cancer

An essential aspect of thyroid cancer (TC) management is personalized and precision medicine. Functional imaging of TC with radioiodine and [18F]FDG has been frequently used in disease evaluation for several decades now. Recently, advances in molecular imaging have led to the development of novel tracers based on aptamer, peptide, antibody, nanobody, antibody fragment, and nanoparticle platforms. The emerging targets-including HER2, CD54, SHP2, CD33, and more-are promising targets for clinical translation soon. The significance of these tracers may be realized by outlining the way they support the management of TC. The provided examples focus on where preclinical investigations can be translated. Furthermore, advances in the molecular imaging of TC may inspire the development of novel therapeutic or theranostic tracers. In this review, we summarize TC-targeting probes which include transporter-based and immuno-based imaging moieties. We summarize the most recent evidence in this field and outline how these emerging strategies may potentially optimize clinical practice.

Site-Specific Radiolabeling of a Human PD-L1 Nanobody via Maleimide-Cysteine Chemistry

Immune checkpoint inhibitors targeting the programmed cell death-1 (PD-1) and its ligand PD-L1 have proven to be efficient cancer therapies in a subset of patients. From all the patients with various cancer types, only 20% have a positive response. Being able to distinguish patients that do express PD-1/PD-L1 from patients that do not allows patients to benefit from a more personalized and efficient treatment of tumor lesion(s). Expression of PD-1 and PD-L1 is typically assessed via immunohistochemical detection in a tumor biopsy. However, this method does not take in account the expression heterogeneity within the lesion, nor the possible metastasis. To visualize whole-body PD-L1 expression by PET imaging, we developed a nanobody-based radio-immunotracer targeting PD-L1 site-specifically labeled with gallium-68. The cysteine-tagged nanobody was site-specifically conjugated with a maleimide (mal)-NOTA chelator and radiolabeling was tested at different nanobody concentrations and temperatures. Affinity and specificity of the tracer, referred to as [⁶⁸Ga]Ga-NOTA-mal-hPD-L1 Nb, were assayed by surface plasmon resonance and on PD-L1^POS or PD-L1^NEG 624-MEL cells. Xenografted athymic nude mice bearing 624-MEL PD-L1^POS or PD-L1^NEG tumors were injected with the tracer and ex vivo biodistribution was performed 1 h 20 min post-injection. Ideal ⁶⁸Ga-labeling conditions were found at 50 °C for 15 min. [⁶⁸Ga]Ga-NOTA-mal-hPD-L1 Nb was obtained in 80 ± 5% DC-RCY with a RCP > 99%, and was stable in injection buffer and human serum up to 3 h (>99% RCP). The in vitro characterization showed that the NOTA-functionalized Nb retained its affinity and specificity. Ex vivo biodistribution revealed a tracer uptake of 1.86 ± 0.67% IA/g in the positive tumors compared with 0.42 ± 0.04% IA/g in the negative tumors. Low background uptake was measured in the other organs and tissues, except for the kidneys and bladder, due to the expected excretion route of Nbs. The data obtained show that the site-specific ⁶⁸Ga-labeled NOTA-mal-hPD-L1 Nb is a promising PET radio-immunotracer due to its ease of production, stability and specificity for PD-L1.

Optical Biosensors for Virus Detection: Prospects for SARS-CoV-2/COVID-19

The recent pandemic of the novel coronavirus disease 2019 (COVID-19) has caused huge worldwide disruption due to the lack of available testing locations and equipment. The use of optical techniques for viral detection has flourished in the past 15 years, providing more reliable, inexpensive, and accurate detection methods. In the current minireview, optical phenomena including fluorescence, surface plasmons, surface-enhanced Raman scattering (SERS), and colorimetry are discussed in the context of detecting virus pathogens. The sensitivity of a viral detection method can be dramatically improved by using materials that exhibit surface plasmons or SERS, but often this requires advanced instrumentation for detection. Although fluorescence and colorimetry lack high sensitivity, they show promise as point-of-care diagnostics because of their relatively less complicated instrumentation, ease of use, lower costs, and the fact that they do not require nucleic acid amplification. The advantages and disadvantages of each optical detection method are presented, and prospects for applying optical biosensors in COVID-19 detection are discussed.

Dendrimers based cancer nanotheranostics: An overview

Cancer is a known deadliest disease that requires a judicious diagnostic, targeting, and treatment strategy for an early prognosis and selective therapy. The major pitfalls of the conventional approach are non-specificity in targeting, failure to precisely monitor therapy outcome, and cancer progression leading to malignancies. The unique physicochemical properties offered by nanotechnology derived nanocarriers have the potential to radically change the landscape of cancer diagnosis and therapeutic management. An integrative approach of utilizing both diagnostic and therapeutic functionality using a nanocarrier is termed as nanotheranostic. The nanotheranostics platform is designed in such a way that overcomes various biological barriers, efficiently targets the payload to the desired locus, and simultaneously supports planning, monitoring, and verification of treatment delivery to demonstrate an enhanced therapeutic efficacy. Thus, a nanotheranostic platform could potentially assist in drug targeting, image-guided focal therapy, drug release and distribution monitoring, predictionof treatment response, and patient stratification. A class of highly branched nanocarriers known as dendrimers is recognized as an advanced nanotheranostic platform that has the potential to revolutionize the oncology arena by its unique and exciting features. A dendrimer is a well-defined three-dimensional globular chemical architecture with a high level of monodispersity, amenability of precise size control, and surface functionalization. All the dendrimer properties exhibit a reproducible pharmacokinetic behavior that could ensure the desired biodistribution and efficacy. Dendrimers are thus being exploited as a nanotheranostic platform embodying a diverse class of therapeutic, imaging, and targeting moieties for cancer diagnosis and treatment.

Precision Oncology, Signaling and Anticancer Agents in Cancer Therapeutics

BACKGROUND

The global alliance for genomics and healthcare facilities provides innovational solutions to expedite research and clinical practices for complex and incurable health conditions. Precision oncology is an emerging field explicitly tailored to facilitate cancer diagnosis, prevention and treatment based on patients' genetic profile. Advancements in "omics" techniques, next-generation sequencing, artificial intelligence and clinical trial designs provide a platform for assessing the efficacy and safety of combination therapies and diagnostic procedures.

METHOD

Data were collected from Pubmed and Google scholar using keywords: "Precision medicine", "precision medicine and cancer", "anticancer agents in precision medicine" and reviewed comprehensively.

RESULTS

Personalized therapeutics including immunotherapy, cancer vaccines, serve as a groundbreaking solution for cancer treatment. Herein, we take a measurable view of precision therapies and novel diagnostic approaches targeting cancer treatment. The contemporary applications of precision medicine have also been described along with various hurdles identified in the successful establishment of precision therapeutics.

CONCLUSION

This review highlights the key breakthroughs related to immunotherapies, targeted anticancer agents, and target interventions related to cancer signaling mechanisms. The success story of this field in context to drug resistance, safety, patient survival and in improving quality of life is yet to be elucidated. We conclude that, in the near future, the field of individualized treatments may truly revolutionize the nature of cancer patient care.

Diffusion-weighted imaging with background body signal suppression (DWIBS) distinguishes benign lesions from malignant pulmonary solitary lesions

This study aimed to determine applicable value of DWIBS in diagnosis of solitary pulmonary lesions. This study involved 32 solitary lung disease patients. T1W1, T2W1, T2WI-SPAIR were examined using MRI scanner and analyzed with View-forum 6.0 workstation. Imaging characteristics of pulmonary solitary lesions on DWIBS and ADC when b=300, 500 and 800 s/mm² were observed. Signal-to-noise ratio (SNR), contrast-noise-ratio (CNR) and ADC value of lesions under different b-values were measured. Image quality in different b-values was compared by analyzing SNR and CNR. ADC values of benign and malignant lesions in different b-value groups were tested using t-test. ROC curve was used to evaluate diagnostic efficacy of ADC value, and obtain diagnostic threshold. The results indicated that SNR and CNR value of 300 and 500 s/mm² group was significantly higher compared to 800 s/mm² group (P<0.05). When b-value was assigned as 500 s/mm², DWIBS demonstrated better and ideal images. ADC value of malignant lesions in different b-values was significantly lower compared to benign lesions (P<0.05), suggesting ADC value is a feasible approach for distinguishing benign from malignant lesions. AUC value of b=500 s/mm² was significantly higher compared to b=300 and b=800 s/mm² group (P<0.05). When b-value was assigned as 500 s/mm², the best ADC threshold value was 1.435×10^-3 mm²/s, with high sensitivity, specificity and accuracy of 80.0%, 83.3% and 84.4%, respectively. In conclusion, quantitative analysis of DWIBS examination and ADC value was helpful for qualitative diagnosis of pulmonary solitary lesions, and demonstrated potential to distinguish benign and malignant pulmonary solitary lesions.

Advances in Medical Imaging: Aptamer- and Peptide-Targeted MRI and CT Contrast Agents

Computed tomography (CT) and magnetic resonance imaging (MRI) are among the most well-established modalities in the field of noninvasive medical imaging. Despite being powerful tools, both suffer from a number of limitations and often fall short when it comes to full delineation of pathological tissues. Since its conception, molecular imaging has been commonly utilized to further the understanding of disease progression, as well as monitor treatment efficacy. This has naturally led to the advancement of the field of targeted imaging. Targeted imaging research is currently dominated by ligand-modified contrast media for applications in MRI and CT imaging. Although a plethora of targeting ligands exist, a fine balance between their size and target binding efficiency must be considered. This review will focus on aptamer- and peptide-modified contrast agents, outlining selected formulations developed in recent years while highlighting the advantages offered by these targeting ligands.

Polymeric Nanoparticles for Drug Delivery: Recent Developments and Future Prospects

The complexity of some diseases—as well as the inherent toxicity of certain drugs—has led to an increasing interest in the development and optimization of drug-delivery systems. Polymeric nanoparticles stand out as a key tool to improve drug bioavailability or specific delivery at the site of action. The versatility of polymers makes them potentially ideal for fulfilling the requirements of each particular drug-delivery system. In this review, a summary of the state-of-the-art panorama of polymeric nanoparticles as drug-delivery systems has been conducted, focusing mainly on those applications in which the corresponding disease involves an important morbidity, a considerable reduction in the life quality of patients—or even a high mortality. A revision of the use of polymeric nanoparticles for ocular drug delivery, for cancer diagnosis and treatment, as well as nutraceutical delivery, was carried out, and a short discussion about future prospects of these systems is included.

PLGA-Based Drug Delivery Systems for Remotely Triggered Cancer Therapeutic and Diagnostic Applications

Intelligent drug delivery systems based on nanotechnology have been widely developed and investigated in the field of nanomedicine since they were able to maximize the therapeutic efficacy and minimize the undesirable adverse effects. Among a variety of organic or inorganic nanomaterials available to fabricate drug delivery systems (DDSs) for cancer therapy and diagnosis, poly(D,L-lactic-co-glycolic acid) (PLGA) has been extensively employed due to its biocompatibility and biodegradability. In this paper, we review the recent status of research on the application of PLGA-based drug delivery systems (DDSs) in remotely triggered cancer therapy and the strategies for tumor imaging provided by PLGA-based DDSs. We firstly discuss the employment of PLGA-based DDSs for remotely triggered cancer therapy, including photo-triggered, ultrasound-triggered, magnetic field-triggered, and radiofrequency-triggered cancer therapy. Photo-triggered cancer therapy involves photodynamic therapy (PDT), photothermal therapy (PTT), and photo-triggered chemotherapeutics release. Ultrasound-triggered cancer therapy involves high intensity focused ultrasound (HIFU) treatment, ultrasound-triggered chemotherapeutics release, and ultrasound-enhanced efficiency of gene transfection. The strategies which endows PLGA-based DDSs with imaging properties and the PLGA-based cancer theranostics are further discussed. Additionally, we also discuss the targeting strategies which provide PLGA-based DDSs with passive, active or magnetic tumor-targeting abilities. Numerous studies cited in our review demonstrate the great potential of PLGA-based DDSs as effective theranostic agent for cancer therapy and diagnosis.

Recent Advances of Bioresponsive Nano-Sized Contrast Agents for Ultra-High-Field Magnetic Resonance Imaging

The ultra-high-field magnetic resonance imaging (MRI) nowadays has been receiving enormous attention in both biomaterial research and clinical diagnosis. MRI contrast agents are generally comprising of T1-weighted and T2-weighted contrast agent types, where T1-weighted contrast agents show positive contrast enhancement with brighter images by decreasing the proton's longitudinal relaxation times and T2-weighted contrast agents show negative contrast enhancement with darker images by decreasing the proton's transverse relaxation times. To meet the incredible demand of MRI, ultra-high-field T2 MRI is gradually attracting the attention of research and medical needs owing to its high resolution and high accuracy for detection. It is anticipated that high field MRI contrast agents can achieve high performance in MRI imaging, where parameters of chemical composition, molecular structure and size of varied contrast agents show contrasted influence in each specific diagnostic test. This review firstly presents the recent advances of nanoparticle contrast agents for MRI. Moreover, multimodal molecular imaging with MRI for better monitoring is discussed during biological process. To fasten the process of developing better contrast agents, deep learning of artificial intelligent (AI) can be well-integrated into optimizing the crucial parameters of nanoparticle contrast agents and achieving high resolution MRI prior to the clinical applications. Finally, prospects and challenges are summarized.

10-Fold Quantum Yield Improvement of Ag2S Nanoparticles by Fine Compositional Tuning

Ag₂S semiconductor nanoparticles (NPs) are near-infrared luminescent probes with outstanding properties (good biocompatibility, optimum spectral operation range, and easy biofunctionalization) that make them ideal probes for in vivo imaging. Ag₂S NPs have, indeed, made possible amazing challenges including in vivo brain imaging and advanced diagnosis of the cardiovascular system. Despite the continuous redesign of synthesis routes, the emission quantum yield (QY) of Ag₂S NPs is typically below 0.2%. This leads to a low luminescent brightness that avoids their translation into the clinics. In this work, an innovative synthetic methodology that permits a 10-fold increment in the absolute QY from 0.2 up to 2.3% is presented. Such an increment in the QY is accompanied by an enlargement of photoluminescence lifetimes from 184 to 1200 ns. The optimized synthetic route presented here is based on a fine control over both the Ag core and the Ag/S ratio within the NPs. Such control reduces the density of structural defects and decreases the nonradiative pathways. In addition, we demonstrate that the superior performance of the Ag₂S NPs allows for high-contrast in vivo bioimaging.

Ultrasound molecular imaging: insights into cardiovascular pathology

Similar to what has already occurred in cancer medicine, the management of cardiovascular conditions will likely be improved by non-invasive molecular imaging technologies that can provide earlier or more accurate diagnosis. These techniques are already having a positive impact in pre-clinical research by providing insight into pathophysiology or efficacy of new therapies. Contrast enhanced ultrasound (CEU) molecular imaging is a technique that relies on the ultrasound detection of targeted microbubble contrast agents to examine molecular or cellular events that occur at the blood pool-endothelial interface. CEU molecular imaging techniques have been developed that are able to provide unique information on atherosclerosis, ischemia reperfusion injury, angiogenesis, vascular inflammation, and thrombus formation. Accordingly, CEU has the potential to be used in a wide variety of circumstances to detect disease early or at the bedside, and to guide appropriate therapy based on vascular phenotype. This review will describe the physical basis for CEU molecular imaging, and the specific disease processes for the pre-clinical translational research experience.

Therapeutic Efficiency of Multiple Applications of Magnetic Hyperthermia Technique in Glioblastoma Using Aminosilane Coated Iron Oxide Nanoparticles: In Vitro and In Vivo Study

Magnetic hyperthermia (MHT) has been shown as a promising alternative therapy for glioblastoma (GBM) treatment. This study consists of three parts: The first part evaluates the heating potential of aminosilane-coated superparamagnetic iron oxide nanoparticles (SPIONa). The second and third parts comprise the evaluation of MHT multiple applications in GBM model, either in vitro or in vivo. The obtained heating curves of SPIONa (100 nm, +20 mV) and their specific absorption rates (SAR) stablished the best therapeutic conditions for frequencies (309 kHz and 557 kHz) and magnetic field (300 Gauss), which were stablished based on three in vitro MHT application in C6 GBM cell line. The bioluminescence (BLI) signal decayed in all applications and parameters tested and 309 kHz with 300 Gauss have shown to provide the best therapeutic effect. These parameters were also established for three MHT applications in vivo, in which the decay of BLI signal correlates with reduced tumor and also with decreased tumor glucose uptake assessed by positron emission tomography (PET) images. The behavior assessment showed a slight improvement after each MHT therapy, but after three applications the motor function displayed a relevant and progressive improvement until the latest evaluation. Thus, MHT multiple applications allowed an almost total regression of the GBM tumor in vivo. However, futher evaluations after the therapy acute phase are necessary to follow the evolution or tumor total regression. BLI, positron emission tomography (PET), and spontaneous locomotion evaluation techniques were effective in longitudinally monitoring the therapeutic effects of the MHT technique.

Monoclonal antibody-based molecular imaging strategies and theranostic opportunities

Molecular imaging modalities hold great potential as less invasive techniques for diagnosis and management of various diseases. Molecular imaging combines imaging agents with targeting moieties to specifically image diseased sites in the body. Monoclonal antibodies (mAbs) have become increasingly popular as novel therapeutics against a variety of diseases due to their specificity, affinity and serum stability. Because of the same properties, mAbs are also exploited in molecular imaging to target imaging agents such as radionuclides to the cell of interest in vivo. Many studies investigated the use of mAb-targeted imaging for a variety of purposes, for instance to monitor disease progression and to predict response to a specific therapeutic agent. Herein, we highlighted the application of mAb-targeted imaging in three different types of pathologies: autoimmune diseases, oncology and cardiovascular diseases. We also described the potential of molecular imaging strategies in theranostics and precision medicine. Due to the nearly infinite repertoire of mAbs, molecular imaging can change the future of modern medicine by revolutionizing diagnostics and response prediction in practically any disease.

Magnetic Resonance Imaging for Translational Research in Oncology

The translation of results from the preclinical to the clinical setting is often anything other than straightforward. Indeed, ideas and even very intriguing results obtained at all levels of preclinical research, i.e., in vitro, on animal models, or even in clinical trials, often require much effort to validate, and sometimes, even useful data are lost or are demonstrated to be inapplicable in the clinic. In vivo, small-animal, preclinical imaging uses almost the same technologies in terms of hardware and software settings as for human patients, and hence, might result in a more rapid translation. In this perspective, magnetic resonance imaging might be the most translatable technique, since only in rare cases does it require the use of contrast agents, and when not, sequences developed in the lab can be readily applied to patients, thanks to their non-invasiveness. The wide range of sequences can give much useful information on the anatomy and pathophysiology of oncologic lesions in different body districts. This review aims to underline the versatility of this imaging technique and its various approaches, reporting the latest preclinical studies on thyroid, breast, and prostate cancers, both on small laboratory animals and on human patients, according to our previous and ongoing research lines.

Lung and Abdominal Biopsies in the Age of Precision Medicine

Image-guided percutaneous needle biopsies (PNBs) are one of the most common procedures performed in radiology departments today. Rapid developments in precision medicine, which identifies molecular and genomic biomarkers in cancers, have ushered a new paradigm of oncologic workup and treatment. PNB has conventionally been used to establish a benign or malignant nature of a lesion during initial diagnosis or in suspected metastatic or recurrent disease. However, increasing amounts of tissue are being required to meet the demands of molecular pathologic analysis, which are now being sought at multiple time points during the course of the disease to guide targeted therapy. As primary providers of biopsy, radiologists must be proactive in these developments to improve diagnostic yield and tissue acquisition in PNB. Herein, we discuss the important and expanding role of PNB in the age of precision medicine and review the technical considerations of percutaneous lung and intra-abdominal biopsy. Finally, we examine promising state-of-the-art techniques in PNB that may safely increase tissue acquisition for optimal molecular pathologic analysis.

Seeing Better and Going Deeper in Cancer Nanotheranostics

Biomedical imaging modalities in clinical practice have revolutionized oncology for several decades. State-of-the-art biomedical techniques allow visualizing both normal physiological and pathological architectures of the human body. The use of nanoparticles (NP) as contrast agents enabled visualization of refined contrast images with superior resolution, which assists clinicians in more accurate diagnoses and in planning appropriate therapy. These desirable features are due to the ability of NPs to carry high payloads (contrast agents or drugs), increased in vivo half-life, and disease-specific accumulation. We review the various NP-based interventions for treatments of deep-seated tumors, involving "seeing better" to precisely visualize early diagnosis and "going deeper" to activate selective therapeutics in situ.

Combining Diagnostic Imaging and Pathology for Improving Diagnosis and Prognosis of Cancer

In the era of personalized medicine, the management of oncological patients requires a translational and multidisciplinary approach. During early phases of cancer development, biochemical alterations of cell metabolism occur much before the formation of detectable tumour masses. Current molecular imaging techniques, targeted to the study of molecular kinetics, employ molecular tracers capable of detecting cancer lesions with both high sensitivity and specificity while also providing essential information for both prognosis and therapy. On the contrary, complementary and crucial information is provided by histopathological examination and ancillary techniques such as immunohistochemistry. Thus, the successful collaboration between diagnostic imaging and anatomic pathology can represent a fundamental step in the "tortuous" but decisive path towards personalized medicine.

Ocular Biodistribution Studies using Molecular Imaging

Classical methodologies used in ocular pharmacokinetics studies have difficulties to obtain information about topical and intraocular distribution and clearance of drugs and formulations. This is associated with multiple factors related to ophthalmic physiology, as well as the complexity and invasiveness intrinsic to the sampling. Molecular imaging is a new diagnostic discipline for in vivo imaging, which is emerging and spreading rapidly. Recent developments in molecular imaging techniques, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), allow obtaining reliable pharmacokinetic data, which can be translated into improving the permanence of the ophthalmic drugs in its action site, leading to dosage optimisation. They can be used to study either topical or intraocular administration. With these techniques it is possible to obtain real-time visualisation, localisation, characterisation and quantification of the compounds after their administration, all in a reliable, safe and non-invasive way. None of these novel techniques presents simultaneously high sensitivity and specificity, but it is possible to study biological procedures with the information provided when the techniques are combined. With the results obtained, it is possible to assume that molecular imaging techniques are postulated as a resource with great potential for the research and development of new drugs and ophthalmic delivery systems.

Theranostics in Interventional Oncology: Versatile Carriers for Diagnosis and Targeted Image-Guided Minimally Invasive Procedures

We are continuously progressing in our understanding of cancer and other diseases and learned how they can be heterogeneous among patients. Therefore, there is an increasing need for accurate characterization of diseases at the molecular level. In parallel, medical imaging and image-guided therapies are rapidly developing fields with new interventions and procedures entering constantly in clinical practice. Theranostics, a relatively new branch of medicine, refers to procedures combining diagnosis and treatment, often based on patient and disease-specific features or molecular markers. Interventional oncology which is at the convergence point of diagnosis and treatment employs several methods related to theranostics to provide minimally invasive procedures tailored to the patient characteristics. The aim is to develop more personalized procedures able to identify cancer cells, selectively reach and treat them, and to assess drug delivery and uptake in real-time in order to perform adjustments in the treatment being delivered based on obtained procedure feedback and ultimately predict response. Here, we review several interventional oncology procedures referring to the field of theranostics, and describe innovative methods that are under development as well as future directions in the field.

Ultrasound Molecular Imaging: Principles and Applications in Cardiovascular Medicine

PURPOSE OF REVIEW

Non-invasive molecular imaging is currently used as a research technique to better understand disease pathophysiology. There are also many potential clinical applications where molecular imaging may provide unique information that allows either earlier or more definitive diagnosis, or can guide precision medicine-based decisions on therapy. Contrast-enhanced ultrasound (CEU) with targeted microbubble contrast agents is one such technique that has been developed that has the unique properties of providing rapid information and revealing information only on events that occur within the vascular space.

RECENT FINDINGS

CEU molecular probes have been developed for a wide variety of disease states including atherosclerosis, vascular inflammation, thrombosis, tumor neovascularization, and ischemic injury. While the technique has not yet been adapted to clinical use, it has been used to reveal pathological processes, to identify new therapeutic targets, and to test the efficacy of novel treatments. This review will explore the physical basis for CEU molecular imaging, its strengths and limitations compared to other molecular imaging modalities, and the pre-clinical translational research experience.

Chemical and photonic interactions in vitro and in vivo between fluorescent tracer and nanoparticle-based scavenger for enhanced molecular imaging

We hereby present a concept of scavenging excess imaging agent prior to a diagnostic imaging session, consequently allowing for enhanced contrast of signals originating from the tissue area of interest to the signals originating from systemic imaging agent residues. In our study, a prospective silica core-shell nanoparticle-based scavenger was designed and explored for its feasibility to scavenge a specific imaging agent (tracer) in the bloodstream. The developed tracer-scavenger system was first investigated under in vitro conditions to ensure proper binding between tracer and scavenger is taking place, as confirmed by Förster/fluorescence resonance energy transfer studies. In vivo, two-photon imaging was utilized to directly study the interaction of the scavenger particles and the tracer molecules in the vasculature of mice. To our knowledge, a methodological solution for in vivo differentiation between signals, originating from tissue and blood, has not been presented elsewhere.

PEGylated peptide to TIP1 is a novel targeting agent that binds specifically to various cancers in vivo

Targeted molecular imaging allows specific visualization and monitoring of tumors. Cancer-specific peptides have been developed for imaging and therapy. Peptides that specifically target cancer have several advantages including, ease of synthesis, low antigenicity, and enhanced diffusion into tissues. We developed the HVGGSSV peptide as a molecular targeting/imaging agent. HVGGSSV targets Tax interacting protein 1 (TIP1) which is a 14 kDa PDZ domain-containing protein that is overexpressed in cancer. We docked HVGGSSV in silico using the three-dimensional structure of TIP1 and found the binding energy was -6.0 kCal/mol. The binding affinity of HVGGSSV to TIP1 protein was found to have a K_D of 3.3 × 10^-6 M using surface plasmon resonance. We conjugated a 40 kDa PEG to HVGGSSV to enhance the circulation and evaluated the tumor binding in nude mice bearing heterotopic cervical (HT3), esophageal (OE33), pancreatic (BXPC3), lung (A549) and glioma (D54) tumors. NanoSPECT/CT imaging of the mice was performed 48 h and 72 h after injecting with ¹¹¹Indium (¹¹¹In) labeled PEG-HVGGSSV or PEG-control peptide. SPECT imaging revealed that ¹¹¹In-PEG-HVGGSSV specifically bound to cervical, esophageal, pancreatic, lung and brain tumors. Post SPECT biodistribution data further validated tumor-specific binding. Overall, HVGGSSV peptide specifically binds to the major groove of the TIP1 protein surface. PEGylated-HVGGSSV could be used to target cancers that overexpress TIP1.

Combination of Cell-Penetrating Peptides with Nanoparticles for Therapeutic Application: A Review

Cell-penetrating peptides (CPPs), also known as protein translocation domains, membrane translocating sequences or Trojan peptides, are small molecules of 6 to 30 amino acid residues capable of penetrating biological barriers and cellular membranes. Furthermore, CPP have become an alternative strategy to overcome some of the current drug limitations and combat resistant strains since CPPs are capable of delivering different therapeutic molecules against a wide range of diseases. In this review, we address the recent conjugation of CPPs with nanoparticles, which constitutes a new class of delivery vectors with high pharmaceutical potential in a variety of diseases.

Tumor Retention of Enzyme-Responsive Pt(II) Drug-Loaded Nanoparticles Imaged by Nanoscale Secondary Ion Mass Spectrometry and Fluorescence Microscopy

In nanomedicine, determining the spatial distribution of particles and drugs, together and apart, at high resolution within tissues, remains a major challenge because each must have a different label or detectable feature that can be observed with high sensitivity and resolution. We prepared nanoparticles capable of enzyme-directed assembly of particle therapeutics (EDAPT), containing an analogue of the Pt(II)-containing drug oxaliplatin, an 15N-labeled monomer in the hydrophobic block of the backbone of the polymer, the near-infrared dye Cy5.5, and a peptide that is a substrate for tumor metalloproteinases in the hydrophilic block. When these particles reach an environment rich in tumor associated proteases, the hydrophilic peptide substrate is cleaved, causing the particles to accumulate through a morphology transition, locking them in the tumor extracellular matrix. To evaluate the distribution of drug and EDAPT carrier in vivo, the localization of the isotopically labeled polymer backbone was compared to that of Pt by nanoscale secondary ion mass spectrometry (NanoSIMS). The correlation of NanoSIMS with super-resolution fluorescence microscopy revealed the release of the drug from the nanocarrier and colocalization with cellular DNA within tumor tissue. The results confirmed the dependence of particle accumulation and Pt(II) drug delivery on the presence of a Matrix Metalloproteinase (MMP) substrate and demonstrated antitumor activity. We conclude that these techniques are powerful for the elucidation of the localization of cargo and carrier, and enable a high-resolution assessment of their performance following in vivo delivery.

Safety markers for rhabdomyosarcoma cells using an in vivo imaging system

In vivo imaging system (IVIS) is a novel and rapidly expanding technology that is widely applied in life sciences, including cell tracing. IVIS is able to quantify biological events, including tumor proliferation, through counting the number of photons emitted from a specimen. PLA802-enhanced green fluorescent protein (EGFP), PLA802-monomeric cherry fluorescent protein (mCherry), RH30-EGFP and RH30-mCherry tumor cells were injected into 18 BALB/c female nude mice subcutaneously with 5×10⁶ cells in 100 µl to quantitatively analyze EGFP and mCherry cells traced by IVIS. Inversion fluorescence microscopy revealed no transfection efficiency difference between PLA802-EGFP (95.3±1.2%) and PLA802-mCherry (95.8±1.7%), or between RH30-EGFP (94.7±2.1%) and RH30-mCherry (95.2±1.9%). Transfection did not influence the cell morphology of PLA802 or RH30. The cell migration, invasion and proliferation assay results of lentivirus-EGFP and lentivirus-mCherry revealed no significant difference prior to or following transfection. Therefore, lentivirus-EGFP and lentivirus-mCherry may serve as safety biological markers for PLA802 and RH30 cells. In vivo experiments demonstrated that lentivirus-EGFP and lentivirus-mCherry tumor luminescence signals were observed in all mice by IVIS. Hematoxylin-eosin staining and immunohistochemistry indicated that PLA802-EGFP, PLA802-mCherry, RH30-EGFP and RH30-mCherry cell lines exhibited rhabdomyosarcoma (RMS) characteristics like the maternal cells. In summary, mCherry and green fluorescent protein in human RMS PLA802 and RH30 cancer cells may be safely and stably expressed for a long time in vitro and in vivo.

Advances in Retinal Optical Imaging

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

Fabrication, Characterization and Cytotoxicity of Spherical-Shaped Conjugated Gold-Cockle Shell Derived Calcium Carbonate Nanoparticles for Biomedical Applications

The evolution of nanomaterial in science has brought about a growing increase in nanotechnology, biomedicine, and engineering fields. This study was aimed at fabrication and characterization of conjugated gold-cockle shell-derived calcium carbonate nanoparticles (Au-CSCaCO3NPs) for biomedical application. The synthetic technique employed used gold nanoparticle citrate reduction method and a simple precipitation method coupled with mechanical use of a Programmable roller-ball mill. The synthesized conjugated nanomaterial was characterized for its physicochemical properties using transmission electron microscope (TEM), field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). However, the intricacy of cellular mechanisms can prove challenging for nanomaterial like Au-CSCaCO3NPs and thus, the need for cytotoxicity assessment. The obtained spherical-shaped nanoparticles (light-green purplish) have an average diameter size of 35 ± 16 nm, high carbon and oxygen composition. The conjugated nanomaterial, also possesses a unique spectra for aragonite polymorph and carboxylic bond significantly supporting interactions between conjugated nanoparticles. The negative surface charge and spectra absorbance highlighted their stability. The resultant spherical shaped conjugated Au-CSCaCO3NPs could be a great nanomaterial for biomedical applications.

Practical Guidelines for Cerenkov Luminescence Imaging with Clinically Relevant Isotopes

Cerenkov luminescence imaging (CLI) is a relatively new imaging modality that utilizes conventional optical imaging instrumentation to detect Cerenkov radiation derived from standard and often clinically approved radiotracers. Its research versatility, low cost, and ease of use have increased its popularity within the molecular imaging community and at institutions that are interested in conducting radiotracer-based molecular imaging research, but that lack the necessary resources and infrastructure. Here, we provide a description of the materials and procedures necessary to conduct a Cerenkov luminescence imaging experiment using a variety of imaging instrumentation, radionuclides, and animal models.

Near-Infrared Visual Differentiation in Normal and Abnormal Breast Using Hemoglobin Concentrations

Introduction: Near-infrared (NIR) optical imaging is a non-ionizing modality that is emerging as a diagnostic/prognostic tool for breast cancer according to NIR differentiation of hemoglobin (Hb) concentration. Methods: The transmission values of LED-sourced light at 625 nm were measured by power meter to evaluate the optical properties of Hb in breast phantom containing major and minor vessels. For the simulation of blood variations in cancerous breast condition, we prepared 2 concentrations of pre-menopausal Hb and 4 concentrations of post-menopausal Hb and, for comparison with normal tissue, one concentration of Hb injected inside the phantom's vessels. Imaging procedure on the phantom was also conducted by LED source and CCD camera. The images from the experiments were compared with the results obtained from the images analyzed by MATLAB software. Finally, mammography of phantom including various concentration of Hb was prepared. Results: The transmitting intensities of NIR in blood containing 1, 2 and 4 concentrations of Hb in the major vessels were 52.83±2.85, 43.00±3.11 and 31.17±2.27 µW, respectively, and in minor vessels containing similar Hb concentrations were 73.50±2.43, 60.08±5.09 and 42.42±4.86 µW, respectively. The gray-scale levels on the major vessel were about 96, 124, 162 and on the minor vessel about 72, 100, 130 measured for 1, 2 and 4 Hb concentrations, respectively. The sensitivity and specificity of NIR imaging differentiation were 97.4% and 91.3%, respectively. Conclusion: Significant differences in transmitting intensity, optical imaging as well as software analysis of images were observed for 1, 2 and 4 concentrations of Hb in major and minor breast phantom vessels. Differentiation capability of minor vessels was higher than major vessels for Hb concentrations. Despite a good detection for location of vessels by mammography, it could not show differences between vessels with various concentrations. However, NIR optical imaging demonstrated a good image contrast for showing vessels in terms of concentration. This study recommends NIR optical imaging for prescreening breast cancer due to its potential for early diagnosis.

Preclinical Imaging for the Study of Mouse Models of Thyroid Cancer

Thyroid cancer, which represents the most common tumors among endocrine malignancies, comprises a wide range of neoplasms with different clinical aggressiveness. One of the most important challenges in research is to identify mouse models that most closely resemble human pathology; other goals include finding a way to detect markers of disease that common to humans and mice and to identify the most appropriate and least invasive therapeutic strategies for specific tumor types. Preclinical thyroid imaging includes a wide range of techniques that allow for morphological and functional characterization of thyroid disease as well as targeting and in most cases, this imaging allows quantitative analysis of the molecular pattern of the thyroid cancer. The aim of this review paper is to provide an overview of all of the imaging techniques used to date both for diagnosis and theranostic purposes in mouse models of thyroid cancer.