bims-mricoa Biomed News
on MRI contrast agents
Issue of 2022‒02‒20
nine papers selected by
Merve Yavuz
Bilkent University

  1. Nanomaterials (Basel). 2022 Jan 28. pii: 456. [Epub ahead of print]12(3):
      Exchange bias (EB) properties have become especially important in hollow magnetic nanoparticles (MNPs) due to the versatility and reduced size of these materials. In this work, we present the synthesis and study of the EB properties of iron-oxide-based hollow MNPs and their precursors Fe/iron oxide MNPs with core/void/shell structure. The two mechanisms involved in EB generation were investigated: the frozen spins present in the nanograins that form the nanoparticles and the surface spins. The effect of external parameters on the coercivity (HC), remanence (MR), exchange bias field (HEB) and frozen spins, such as cooling field (HFC) and temperature, was investigated. Both HC and HEB present a maximum threshold above which their values begin to decrease with HFC, showing a new trend of HEB with HFC and allowing modulation on demand. The existence of surface spins, present on the outer and inner surfaces, was demonstrated, and an intrinsic EB phenomenon (HEB = 444 Oe for hollow iron oxide-based MNPs of 13.1 nm) with significant magnetization (MS~50 emu/g) was obtained. Finally, core/void/shell MNPs of 11.9 nm prior to the formation of the hollow MNPs showed a similar behavior, with non-negligible HEB, highlighting the importance of surface spins in EB generation.
    Keywords:  exchange bias; interfacial effects; magnetic nanoparticles; nanomagnetism; surface spins
  2. Nanomaterials (Basel). 2022 Jan 21. pii: 343. [Epub ahead of print]12(3):
      This paper describes the preparation and obtained magnetic properties of large single domain iron oxide nanoparticles. Such ferrimagnetic particles are particularly interesting for diagnostic and therapeutic applications in medicine or (bio)technology. The particles were prepared by a modified oxidation method of non-magnetic precursors following the green rust synthesis and characterized regarding their structural and magnetic properties. For increasing preparation temperatures (5 to 85 °C), an increasing particle size in the range of 30 to 60 nm is observed. Magnetic measurements confirm a single domain ferrimagnetic behavior with a mean saturation magnetization of ca. 90 Am2/kg and a size-dependent coercivity in the range of 6 to 15 kA/m. The samples show a specific absorption rate (SAR) of up to 600 W/g, which is promising for magnetic hyperthermia application. For particle preparation temperatures above 45 °C, a non-magnetic impurity phase occurs besides the magnetic iron oxides that results in a reduced net saturation magnetization.
    Keywords:  hyperthermia; hysteresis; large single domain; magnetic iron oxide nanoparticles
  3. Curr Cancer Drug Targets. 2022 Feb 11.
      Ferroptosis is an iron-dependent nonapoptotic kind of regulated cell death resulting from the destruction of redox balance in the cytosol. Unlike apoptosis, ferroptosis is caused by an increase in intracellular iron and lipid peroxides that causes significant damage to the membrane lipid bilayer and mitochondria, which leads to cell death. Increased iron level in the cell promotes ROS production. Ferroptosis inducer molecules increase ROS production and inhibit the antioxidant defence mechanism to facilitate ferroptosis in cancer cells. Inhibition of GPX4, redox-active iron availability, and lipid peroxidation are major contributors to ferroptosis. Ferroptosis is involved in many diseases like heart disease, neurodegenerative disease as well as cancer. Ferroptosis induction recently emerged as an attractive strategy for cancer therapy. In this review, we discuss the regulatory mechanism of ferroptosis, its different hallmarks, including genetic and metabolic regulators and inducers that promote ferroptosis in the cancer cells. Finally, the latest progress and development in ferroptosis research in different cancer with a focus on proposing a novel strategy in cancer therapy, are discussed.
    Keywords:  Ferroptosis; cancer; hallmarks; inducer.; redox imbalance; regulated cell death
  4. Sci China Chem. 2022 Jan 26. 1-11
      Information-rich molecules provide opportunities for evolution. Genetically engineered materials are superior in that their properties are coded within genetic sequences and could be fine-tuned. In this review, we elaborate the concept of genetically engineered materials (GEMs) using examples ranging from engineered protein materials to engineered living materials. Protein-based materials are the materials of choice by nature. Recent progress in protein engineering has led to opportunities to tune their sequences for optimal material performance. Proteins also play a central role in living materials where they act in concert with other biological components as well as nonbiological cofactors, giving rise to living features. While the existing GEMs are often limited to those constructed by building blocks of biological origin, being genetically engineerable does not preclude nonbiologic or synthetic materials, the latter of which have yet to be fully explored.
    Keywords:  genetic engineering; living materials; protein; self-assembly
  5. Mol Cancer. 2022 02 12. 21(1): 47
      Ferroptosis is an intracellular iron-dependent form of cell death that is distinct from apoptosis, necrosis, and autophagy. Extensive studies suggest that ferroptosis plays a pivotal role in tumor suppression, thus providing new opportunities for cancer therapy. The development of resistance to cancer therapy remains a major challenge. A number of preclinical and clinical studies have focused on overcoming drug resistance. Intriguingly, ferroptosis has been correlated with cancer therapy resistance, and inducing ferroptosis has been demonstrated to reverse drug resistance. Herein, we provide a detailed description of the mechanisms of ferroptosis and the therapeutic role of regulating ferroptosis in reversing the resistance of cancer to common therapies, such as chemotherapy, targeted therapy and immunotherapy. We discuss the prospect and challenge of regulating ferroptosis as a therapeutic strategy for reversing cancer therapy resistance and expect that our review could provide some references for further studies.
    Keywords:  Chemotherapy; Drug resistance; Ferroptosis; Immunotherapy; Targeted therapy
  6. Nanomaterials (Basel). 2022 Jan 18. pii: 303. [Epub ahead of print]12(3):
      In this study, we report the realization of drug-loaded smart magnetic nanocarriers constituted by superparamagnetic iron oxide nanoparticles encapsulated in a dual pH- and temperature-responsive poly (N-vinylcaprolactam-co-acrylic acid) copolymer to achieve highly controlled drug release and localized magnetic hyperthermia. The magnetic core was constituted by flower-like magnetite nanoparticles with a size of 16.4 nm prepared by the polyol approach, with good saturation magnetization and a high specific absorption rate. The core was encapsulated in poly (N-vinylcaprolactam-co-acrylic acid) obtaining magnetic nanocarriers that revealed reversible hydration/dehydration transition at the acidic condition and/or at temperatures above physiological body temperature, which can be triggered by magnetic hyperthermia. The efficacy of the system was proved by loading doxorubicin with very high encapsulation efficiency (>96.0%) at neutral pH. The double pH- and temperature-responsive nature of the magnetic nanocarriers facilitated a burst, almost complete release of the drug at acidic pH under hyperthermia conditions, while a negligible amount of doxorubicin was released at physiological body temperature at neutral pH, confirming that in addition to pH variation, drug release can be improved by hyperthermia treatment. These results suggest this multi-stimuli-sensitive nanoplatform is a promising candidate for remote-controlled drug release in combination with magnetic hyperthermia for cancer treatment.
    Keywords:  controlled drug release; drug delivery; magnetic hyperthermia; magnetite nanoparticles; pH-responsive nanocarriers; thermo-responsive nanocarriers
  7. Methods Mol Biol. 2022 ;2446 581-593
      Synthetic protein-binding tools based on anti-green fluorescent protein (GFP) nanobodies have recently emerged as useful resources to study developmental biology. By fusing GFP-targeting nanobodies to well-characterized protein domains residing in discrete sub-cellular locations, it is possible to directly and acutely manipulate the localization of GFP-tagged proteins-of-interest in a predictable manner. Here, we describe a detailed protocol for the application of nanobody-based GFP-binding tools, namely Morphotrap and GrabFP, to study the localization and function of extracellular and intracellular proteins in the Drosophila wing imaginal disc. Given the generality of these methods, they are easily applicable for use in other tissues and model organisms.
    Keywords:  Drosophila; GFP; GrabFP; Morphotrap; Nanobody; Protein binders
  8. Methods Mol Biol. 2022 ;2446 531-546
      Over the last two decades, the variable domains from heavy chain-only antibodies in camelids (nanobodies) have emerged as valuable immunoreagents for analytical and diagnostic applications. One prominent use of nanobodies is for the detection of small molecules due to their ease of production, resistance to solvents used in sample extraction, facile genetic manipulation, and small size. These last two properties make it possible to produce biotinylated nanobodies in vivo, which can be loaded in an orientated manner on magnetic beads covered with avidin, creating high-density immunoadsorbenpi twbch ""ts. The method described here details the use of nanobody-based adsorbents to concentrate small molecular weight analytes for subsequent quantitative analysis by MALDI-TOF mass spectrometry. Quantitation requires the inclusion of an internal standard (IS), a compound with properties similar to those of the analyte, enabling compensation for uneven distribution during crystallization of the MALDI-TOF matrix. Since nanobody generation against small compounds requires conjugation to carrier proteins, the same conjugation chemistry can be used to synthesize the IS. By design the IS cross reacts with the capture nanobody and can be preloaded in the immunoadsorbent, facilitating quantitative detection of the target compound.
    Keywords:  Hapten; Immunoadsorbent; Immunoconcentration; Internal standard; Nanobody; Quantitative MALDI-TOF; Streptavidin; VHH
  9. ACS Synth Biol. 2022 Feb 18.
      Reversible computing is a nonconventional form of computing where the inputs and outputs are mapped in a unique one-to-one fashion. Reversible logic gates in single living cells have not been demonstrated. Here, we constructed a synthetic genetic reversible Feynman gate in single E. coli cells, and the input-output relations were measured in a clonal population. The inputs were extracellular chemicals, isopropyl β-d-1-thiogalactopyranoside (IPTG), and anhydrotetracycline (aTc), and the outputs were two fluorescence proteins. We developed a simple mathematical model and simulation to capture the essential features of the circuit and experimentally demonstrated that the behavior of the circuit was ultrasensitive and predictive. We showed an application by creating an intercellular Feynman gate, where input information from bacteria was computed and transferred to HeLa cells through shRNAs delivery and the output signals were observed as silencing of native AKT1 and CTNNB1 genes. The introduction of reversible logics in synthetic biology is new, and given that one-to-one input-output mapping, such reversible genetic systems might have applications in sensing, diagnostics, cellular computing, and synthetic biology.
    Keywords:  Feynman gate; cell−cell interaction; reversible computing; synthetic biology; synthetic genetic circuits