Pharmaceutical grade sodium [99mTc] pertechnetate from low specific activity 99Mo using an automated 99Mo/99mTc-TCM-autosolex generator

New strategies for a sustainable 99mTc supply to meet increasing medical demands: Promising solutions for current problems

The continuing rapid expansion of ^99mTc diagnostic agents always calls for scaling up ^99mTc production to cover increasing clinical demand. Nevertheless, ^99mTc availability depends mainly on the fission-produced ⁹⁹Mo supply. This supply is seriously influenced during renewed emergency periods, such as the past ⁹⁹Mo production crisis or the current COVID-19 pandemic. Consequently, these interruptions have promoted the need for ^99mTc production through alternative strategies capable of providing clinical-grade ^99mTc with high purity. In the light of this context, this review illustrates diverse production routes that either have commercially been used or new strategies that offer potential solutions to promote a rapid production growth of ^99mTc. These techniques have been selected, highlighted, and evaluated to imply their impact on developing ^99mTc production. Furthermore, their advantages and limitations, current situation, and long-term perspective were also discussed. It appears that, on the one hand, careful attention needs to be devoted to enhancing the ⁹⁹Mo economy. It can be achieved by utilizing ⁹⁸Mo neutron activation in commercial nuclear power reactors and using accelerator-based ⁹⁹Mo production, especially the photonuclear transmutation strategy. On the other hand, more research efforts should be devoted to widening the utility of ⁹⁹Mo/^99mTc generators, which incorporate nanomaterial-based sorbents and promote their development, validation, and full automization in the near future. These strategies are expected to play a vital role in providing sufficient clinical-grade ^99mTc, resulting in a reasonable cost per patient dose.

Aptamer-based technology for radionuclide targeted imaging and therapy: a promising weapon against cancer

INTRODUCTION

aptamers are short artificial, single-strand oligonucleotide sequences (DNA, RNA or modified RNA), capable of binding to biological molecules with high affinity and specificity. Due to their relatively low cost of production and scarce immunogenicity, many efforts have been made to produce aptamers directed against specific molecular targets, such as receptors or transporters overexpressed by malignancies.

AREAS COVERED

the technological approaches for generating aptamers are reviewed. Furthermore, the applications of radiolabeled aptamers for the in vivo imaging of several oncological biomarkers through single photon emission computed tomography (SPECT) or positron emission tomography (PET), are covered. Lastly, targeted therapy based on the utilization of aptamers labeled with radionuclides emitting beta particles is discussed, with particular emphasis to the oncological perspectives.

EXPERT OPINION

The main limitation of radiolabeled aptamers is represented by their in vivo sensitivity to endogenous nuclease, so that several strategies have been developed to increase the stability of these compounds. Although the applications of aptamers are still in a preliminary and pre-clinical phase, it is reasonable to hypothesize that this technology will play a major role for personalized medicine in the next years.

A compact solvent extraction based 99Mo/99mTc generator for hospital radiopharmacy

A compact and portable ⁹⁹Mo-^99 mTc generator based on solvent-extraction, mimic to the conventional ⁹⁹Mo-^99 mTc alumina column generator is much-needed commodity for use in hospital radiopharmacy setup. The present study includes the development of a portable, simple and low cost ⁹⁹Mo/^99 mTc-generator based on MEK solvent extraction technique to obtain a very high concentration of no-carrier added (nca) ^99 mTc solution, where low specific activity ⁹⁹Mo source is obtained through ⁹⁸Mo(n, γ)⁹⁹Mo reaction in a research reactor. The unit is intended for operation under the conditions of medical radiological laboratories. Technical trials showed that the mean time of preparation of sodium [^99mTc] pertechnetate radiopharmaceutical did not exceed 15 min. The quality and yield of ^99 mTc-pertechnetate is upto the mark for formulation of radiopharmaceuticals.

Studies on 99Mo–99mTc adsorption and elution behaviors using the inorganic sorbent ceric tungstate and conventional organic resins

Adsorption behavior of 99Mo(VI) and 99mTc(VII) was studied on ceric tungstate (CeW) and compared with the adsorption on the conventional cation and anion exchangers Dowex-50X8 and AG-2X8, respectively. The studies were carried out under static and dynamic conditions. The effect of contact time and pH on the adsorption was investigated under static conditions. High Kd-values for sorption of 99Mo(VI) on (CeW) were obtained over the investigated pH range. 99mTc was adsorbed with much lower Kd-values. The Kd-values were pH dependent. Kd-values of 99Mo-adsorption on AG-2X8 were lower than those on (CeW) and vice versa for 99mTc. Ionic species of both elements were not adsorbed on Dowex-50X8, indicating the absence of cationic species and the adsorption of both elements on AG-2X8 and (CeW) as anionic species. The loading and elution behaviors of 99Mo and 99mTc on (CeW) were studied using different eluents. 99Mo remained strongly adsorbed under all conditions whereas 99mTc was easily eluted. Adsorption of some fission products, i.e. 95Zr(IV) and 95Nb(V), in addition to 123mTe(IV) and 75Se(IV), as representatives of their corresponding fission product isotopes, as well as 181Hf, as probable radioactive contaminant was also studied. Solutions of the ionic species of those metals were loaded in mixtures together with 99Mo on (CeW) columns. Strong adsorption of those ionic species and 99Mo on (CeW) was found whereas 99mTc was easily eluted. Different eluents were investigated for eluting 99mTc from 99Mo-adsorbed on (CeW).

Comparison with adsorption of Re (VII) by two different γ-radiation synthesized silica-grafting of vinylimidazole/4-vinylpyridine adsorbents

Two silica gel based adsorbents for Re (VII), i.e. SS-MPTS-VIMH and SS-MPTS-VPQ, were synthesised. Silica gel was used as the matrix for γ-radiation grafting, and the monomer of 1-vinyl imidazole (VIM) and 4-vinylpyridine (4-VP) was grafted onto the silica silanized by methacryloxy propyl trimethoxyl silane, respectively. A VIM concentration of 2molL^-1 and an absorbed dose of 30kGy were the optimal grafting conditions for adsorbent SS-MPTS-VIM, and a 4-VP concentration of 4molL^-1 and an absorbed dose of 40kGy were the optimal grafting conditions for adsorbent SS-MPTS-VP. At the certain condition, the grafting yield of SS-MPTS-VIM was 30.1% and that of SS-MPTS-VP was 21.0%. The adsorption capacity of adsorbent SS-MPTS-VIMH was 145.99mgg^-1 and that of SS-MPTS-VPQ was 71.08mgg^-1 according to the Langmuir model. The adsorbent SS-MPTS-VPQ had better adsorption properties of acid resistance and anti-interference than SS-MPTS-VIMH. Dynamic column experiments showed that protonated adsorbent SS-MTPS-VIMH could be recycled with good performance while quaternized adsorbent SS-MPTS-VPQ could not. The adsorbent SS-MPTS-VIMH belongs to weak anion exchange adsorbent and SS-MPTS-VPQ belongs to strong anion exchange adsorbent. This study paves a way to the synthesis and application of a novel silica base adsorbents for Re (VII).