bims-mricoa Biomed News
on MRI contrast agents
Issue of 2022‒05‒15
four papers selected by
Merve Yavuz
Bilkent University

  1. Small. 2022 May 13. e2200537
      The demand for highly efficient cancer diagnostic tools increases alongside the high cancer incidence nowadays. Moreover, there is an imperative need for novel cancer treatment therapies that lack the side effects of conventional treatment options. Developments in this aspect employ magnetic nanoparticles (MNPs) for biomedical applications due to their stability, biocompatibility, and magnetic properties. Certain organisms, including many bacteria, can synthesize magnetic nanocrystals, which help their spatial orientation and survival by sensing the earth's geomagnetic field. This work aims to convert Escherichia coli to accumulate magnetite, which can further be coupled with drug delivery modules. The authors design magnetite accumulating bacterial machines using genetic circuitries hiring Mms6 with iron-binding activity and essential in magnetite crystal formation. The work demonstrates that the combinatorial effect of Mms6 with ferroxidase, iron transporter protein, and material binding peptide enhances the paramagnetic behavior of the cells in magnetic resonance imaging (MRI) measurements. Cellular machines are also engineered to display Mms6 peptide on the cell surface via an autotransporter protein that shows augmented MRI performance. The findings are promising for endowing a probiotic bacterium, able to accumulate magnetite intracellularly or extracellularly, serving as a theranostics agent for cancer diagnostics via MRI scanning and hyperthermia treatment.
    Keywords:  genetic circuits; iron oxide nanoparticles; magnetic bacteria; magnetic resonance imaging contrast agents; nanomagnets; synthetic biology
  2. Front Bioeng Biotechnol. 2022 ;10 789016
      Magnetotactic bacteria (MTB) are aquatic microorganisms have the ability to biomineralize magnetosomes, which are membrane-enclosed magnetic nanoparticles. Magnetosomes are organized in a chain inside the MTB, allowing them to align with and traverse along the earth's magnetic field. Magnetosomes have several potential applications for targeted cancer therapy when isolated from the MTB, including magnetic hyperthermia, localized medication delivery, and tumour monitoring. Magnetosomes features and properties for various applications outperform manufactured magnetic nanoparticles in several ways. Similarly, the entire MTB can be regarded as prospective agents for cancer treatment, thanks to their flagella's ability to self-propel and the magnetosome chain's ability to guide them. MTBs are conceptualized as nanobiots that can be guided and manipulated by external magnetic fields and are driven to hypoxic areas, such as tumor sites, while retaining the therapeutic and imaging characteristics of isolated magnetosomes. Furthermore, unlike most bacteria now being studied in clinical trials for cancer treatment, MTB are not pathogenic but might be modified to deliver and express certain cytotoxic chemicals. This review will assess the current and prospects of this burgeoning research field and the major obstacles that must be overcome before MTB can be successfully used in clinical treatments.
    Keywords:  biocompatible; cancer treatment; magnetic field; magnetosomes; magnetotactic bacteria; therapeutic applications.
  3. Front Mol Biosci. 2022 ;9 892957
      Ferroptosis, a novel form of regulated cell death (RCD), has garnered increasing attention in studies on numerous human diseases in the last decade. Emerging evidence has indicated that the pathological process of ferroptosis involves the overloaded production of reactive oxygen species (ROS), followed by aberrant accumulation of lipid peroxidation in an iron-dependent manner, accompanied with an increased uptake of polyunsaturated fatty acids into the cellular membrane, further unfolding an ancient vulnerability in multiple context. The unique nature of ferroptosis differentiates it from other forms of RCD, as it is intricately associated with several biological processes, including the metabolism of iron, amino acids, synthesis of ROS and lipid peroxidation. Accordingly, inducers and inhibitors designed to target the key processes of ferroptosis have been extensively studied. Characterized by its distinct properties as mentioned above and its inducible nature, ferroptosis has been widely implicated in several diseases, and numerous studies have focused on identifying effective therapeutic targets for multiple human diseases, including in cancer, by targeting this process. In the present review, recent studies on the involvement of ferroptosis in several types of cancer are summarized and the findings discussed, highlighting the need for increased contemplation of its involvement in the study of cancer, particularly in the clinical setting. A comprehensive summary of the biological mechanisms underlying ferroptosis, the implications of the multiple inducers of ferroptosis, as well as immunotherapy targeting ferroptosis in different types of cancer is provided in this review to highlight the pathophysiological role of ferroptosis in carcinogenesis, to serve as an aid in future studies on the role of ferroptosis in cancer.
    Keywords:  AT-rich interaction domain 1A; chromatin accessibility; ether lipid; ferroptosis; ferroptosis suppressor protein 1; glutathione peroxidase 4; iron metabolism; lipid peroxidation
  4. Mater Sci Eng C Mater Biol Appl. 2021 Dec 21. pii: S0928-4931(21)00762-1. [Epub ahead of print] 112622
      Bacteria elimination from water sources is key to obtain drinkable water. Hence, the design of systems with ability to interact with bacteria and remove them from water is an attractive proposal. A diversity of polycationic macromolecules has shown bactericide properties, due to interactions with bacteria membranes. In this work, we have grafted cationic carbosilane (CBS) dendrons and dendrimers on the surface of iron oxide magnetic nanoparticles (MNP), leading to NP (ca. 10 nm) that interact with bacteria by covering bacteria membrane. Application of an external magnetic field removes MNP from solution sweeping bacteria attached to them. The interaction of the MNP with Gram-positive S. aureus bacteria is more sensible to the size of dendritic system covering the MNP, whereas interaction with Gram-negative E. coli bacteria is more sensible to the density of cationic groups. Over 500 ppm of NPM, MNP covered with dendrons captured over 90% of both type of bacteria, whereas MNP covered with dendrimers were only able to capture S. aureus bacteria (over 90%) but not E. coli bacteria. Modified MNP were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), Z potential and dynamic light scattering (DLS). Interaction with bacteria was analyzed by UV, TEM and scanning electron microscopy (SEM). Moreover, the possibility to recycle cationic dendronized MNP was explored.
    Keywords:  Bacteria; Carbosilane; Dendrimer and dendron; Magnetic nanoparticles; Water purification