99mTc–meropenem as a potential SPECT imaging probe for tumor hypoxia

Extraction, purification and radioiodination of Khellin as cancer theranostic agent

Khellin was successfully extracted from Ammi visnaga fruits with a recovery percent of 96.15%. Next radio-iodination of Khellin was successfully achieved with a high yield. The biodistribution study of [131I]iodo-khellin in tumour bearing mice revealed that khellin preferentially localization at tumour tissue. Target prediction study for [131I]iodo-khellin revealed that PI3K and VEGFR are potential targets for iodo-khellin with good affinity. The results of this study potentiate [131I]iodo-khellin as a good theranostic agent for tumour imaging and therapy.

99m Tc-labeled antibiotics for infection diagnosis: Mechanism, action, and progress

Discovery of penicillin marked a turning point in the history of infection therapy which also led to the emergence of bacterial resistance. It is now 100 years to fight with ever-muted variants of pathogens by developing more and more antibiotics. Since 1987 to todate, no successful class of antibiotic was introduced; this three decade period is known as "the discovery void" period. While, the clinically approved antibiotics are gradually dying in front of bacterial resistance due to which bacterial infections are appearing leading cause of death and disability. Nuclear medicine imaging technique is the strongest modality to diagnose and follow-up of deep-seated and complicated infections. However, the selection of radiolabeled antimicrobial agents plays critical role in gaining sensitivity and specificity of the imaging results. This review comprises of two main sections; first section explains antibiotic targets, and second section explains the imaging efficacy of ^99m Tc-labeled antimicrobial agents against bacterial infection along with the emphasis on progress and update of ^99m Tc-labeled antibiotics as infection imaging probes. The review, in conclusion, could be an acceleration for radiopharmaceutical chemists for designing and developing ^99m Tc-labeled antimicrobial agents to improve infection imaging quality.

Radiosynthesis, molecular modeling and biodistribution of 99mTc-Protoporphyrin as a preclinical model for tumor diagnosis

Porphyrins are among the most important and widely used compounds involved in a variety of chemical and biochemical applications. These molecules exhibit very special properties that encourage researchers to label many derivatives with diagnostic or therapeutic radionuclides for medical applications. This study reports the radiolabeling and biodistribution of [Formula: see text]Tc-protoporphyrin IX ([Formula: see text]Tc-PPIX) as a novel potential solid-tumor imaging agent. The factors affecting the radiolabeling process were varied to achieve maximum radiochemical yield. [Formula: see text]Tc-PPIX was obtained in high yield of 97.34 ± 0.21% and high stability in serum up to 24 h. The radiochemical yield of [Formula: see text]Tc-PPIX was assessed by a combination of a paper chromatographic technique and HPLC. A computational analysis for all the potential structures that may be formed due to the interaction between protoporphyrin IX and technetium was performed via the DFT method of calculations in gas phase to predict the most likely structure. Molecular docking was further employed to shed light on the nature of the interaction between the most stable complexes with the target protein. Finally, the in-vivo biodistribution of [Formula: see text]Tc-PPIX complex was evaluated in solid-tumor-bearing mice and high tumor/tissue ratio of 5.17 ± 0.34 at 60 min post injection was obtained. Our finding clearly suggests [Formula: see text]Tc-PPIX as a potential SPECT agent for tumor imaging.

A novel 99m Tc-diester complex as tumor targeting agent: Synthesis, radiolabeling, and biological distribution study

The target of this study is the synthesis of a new diester derivative and radiolabeling with one of the most effective diagnostic radioisotopes to be investigated as a novel targeting radiotracer for tumor imaging. 10-[2-(9-Carboxynonanoyloxy)propoxy]-10-oxodecanoic acid was synthesized in excellent yield and characterized by Fourier-transform infrared spectroscopy, mass, 1 H-NMR, and 13 C-NMR spectra. The diester was technetium-99m (99m Tc) radiolabeled by direct technique using sodium dithionite as a reducing agent. The labeling parameters such as diester amount, reducing agent amount, pH of the medium, and reaction time were optimized. High radiochemical yield of 95.10 ± 0.41% and in vitro stability in serum up to 12 h have been obtained on complexation of the synthesized diester with Tc-99m. Evaluation of the diester anticancer activity against breast cancer cell line (MCF-7) showed high percent of inhibition about 61.5% at 100 μg/ml. The rhenium complex of the diester was synthesized and characterized by liquid chromatography-mass spectrometry (ESI) and elemental analysis depending on the strong chemical resemblance between Tc and Re. Biodistribution studies of 99m Tc-diester complex showed high target to nontarget ratio (T/NT) equals 6.24 ± 0.09 in tumor-bearing mice at 30-min postinjection, suggesting this complex could be used as hopeful solid tumor-imaging agent.

99mTc-doxorubicin-loaded gallic acid-gold nanoparticles (99mTc-DOX-loaded GA-Au NPs) as a multifunctional theranostic agent

The development of cancer theranostic nanomedicines is recommended to concurrently achieve and evaluate the therapeutic benefit and progress. The current work aims to develop gallic acid-gold nanoparticles (GA-Au NPs) as a theranostic probe for ^99mTc-Doxorubicin (^99mTc-DOX) based on the spatiotemporal release pattern induced intra-tumoral (IT) delivery. DOX-loaded GA-Au NPs were developed and identified via UV-Vis spectroscopy. The system was characterized for drug loading efficiency%, particle size, zeta potential, topography, in vitro DOX release and anti-proliferative activity against the MCF-7 cell-line. The factors influencing radiolabeling efficiency of DOX with ^99mTc (DOX concentration, stannous chloride concentration, reaction time and pH) were optimized. The in vitro stability in mice serum and in vivo distribution studies in mice of ^99mTc-DOX-loaded GA-Au NPs were investigated following IV and IT administration. Dox-loaded GA-Au NPs had a loading efficiency of 91%, a small particle size (≈50 nm), a promising zeta potential (-20 mV) and a sustained drug release profile at pH 5.3. GA-Au NPs exhibited increased anti-proliferative activity, with approximately a four-fold lower IC₅₀ value (0.15 μg/ml) than free DOX. The optimized radiolabeling efficiency of ^99mTc-DOX was ≈93%. It showed good physiological stability in mice serum for at least 8 h. The IT delivery of ^99mTc-DOX-loaded GA-Au NPs in tumor-induced mice showed dramatic tumor accumulation. A maximum magnitude of 86.73%ID/g was achieved, at 15 min post-injection, with a target/non-target ratio of ≈56. ^99mTc-DOX-loaded GA-Au NPs could be used for the selective IT delivery of a chemotherapeutic agent and an imaging agent to a target organ.

99mTc-gallic-gold nanoparticles as a new imaging platform for tumor targeting

Early and accurate detection of tumor assists in identifying more effective therapies. Gold nanoparticles (GNPs) were synthesized by green synthesis method using gallic acid (GA) then characterized and labeled with technetium-99m. This new platform was biologically evaluated in both normal and solid tumor bearing mice. The in-vivo study of [^99mTc]Tc-gallic-GNPs via both I.V. and I.T injecton showed a high accumulation in tumor site. As a result, [^99mTc]Tc-gallic-GNPs can be afforded as a potential nano-platform for tumor imaging.

Imaging the Tumor Microenvironment

The tumor microenvironment consists of tumor, stromal, and immune cells, as well as extracellular milieu. Changes in numbers of these cell types and their environments have an impact on cancer growth and metastasis. Non-invasive imaging of aspects of the tumor microenvironment can provide important information on the aggressiveness of the cancer, whether or not it is metastatic, and can also help to determine early response to treatment. This chapter provides an overview on non-invasive in vivo imaging in humans and mouse models of various cell types and physiological parameters that are unique to the tumor microenvironment. Current clinical imaging and research investigation are in the areas of nuclear imaging (positron emission tomography (PET) and single photon emission computed tomography (SPECT)), magnetic resonance imaging (MRI) and optical (near infrared (NIR) fluorescence) imaging. Aspects of the tumor microenvironment that have been imaged by PET, MRI and/or optical imaging are tumor associated inflammation (primarily macrophages and T cells), hypoxia, pH changes, as well as enzymes and integrins that are highly prevalent in tumors, stroma and immune cells. Many imaging agents and strategies are currently available for cancer patients; however, the investigation of novel avenues for targeting aspects of the tumor microenvironment in pre-clinical models of cancer provides the cancer researcher with a means to monitor changes and evaluate novel treatments that can be translated into the clinic.

Radioiodinated famotidine as a new highly selective radiotracer for peptic ulcer disorder detection, diagnostic nuclear imaging and biodistribution

Famotidine was labeled with iodine-125 to obtain 125I-famotidine (125I-fam) as an agent for ulcer imaging. The radiochemical yield of 125I-famotidine reached approximately 98.5 ± 0.23% at optimum conditions of pH, oxidizing agent, reaction time and the amount of substrate. 125I-fam was stable for 48 h. Different chromatographic techniques were used to determine the radiochemical yield and purity. Intravenous biodistribution studies of 125I-fam revealed high concentration in the stomach ulcer, reaching about 65.9 ± 0.28% of the total injected dose at 30 min post injection. This concentration of 125I-fam in stomach ulcer makes this agent promising for stomach ulcer imaging.

Platelet-12 lipoxygenase targeting via a newly synthesized curcumin derivative radiolabeled with technetium-99m

Background

One of the most popular techniques for cancer detection is the nuclear medicine technique. The present research focuses on Platelet-12-lipoxygenase (P-12-LOX) as a promising target for treating and radio-imaging tumor tissues. Curcumin was reported to inhibit this enzyme via binding to its active site.

Results

A novel curcumin derivative was successfully synthesized and characterized with yield of 74%. It was radiolabeled with the diagnostic radioisotope technetium-99m with 84% radiochemical yield and in vitro stability up to 6 h. The biodistribution studies in tumor bearing mice confirmed the high affinity predicted by the docking results with a free binding energy value of (ΔG −50.10 kcal/mol) and affinity (13.64 pki) showing high accumulation in solid tumor with target/non-target ratio >6.

Conclusion

The newly synthesized curcumin derivative, as a result of a computational study on platelet-12 lipoxygenase, showed its excellent free binding energy (∆G −50.10 kcal/mol) and high affinity (13.64 pKi). It could be an excellent radio-imaging agent that targeting tumor cells via targeting of P-12-LOX.Graphical abstract