bims-mricoa Biomed News
on MRI contrast agents
Issue of 2021‒12‒05
nine papers selected by
Merve Yavuz
Bilkent University

  1. ACS Omega. 2021 Nov 23. 6(46): 31161-31167
      Magnetic nanoparticles have an important role as heat generators in magnetic fluid hyperthermia, a type of next-generation cancer treatment. Despite various trials to improve the heat generation capability of magnetic nanoparticles, iron oxide nanoparticles are the only approved heat generators for clinical applications, which require a large injection dose due to their low hyperthermia efficiency. In this study, iron oxide nanoclusters (NCs) with a highly enhanced hyperthermia effect and adjustable size were synthesized through a facile and simple solvothermal method. Among the samples, the NCs with a size of 25 nm showed the highest hyperthermia efficiency. Differently sized NCs exhibit inconsistent interparticle crystalline alignments, which affect their magnetic properties (e.g., coercivity and saturation magnetization). As a result, the optimal NCs exhibited a significantly enhanced heat generation efficiency compared with that of isolated iron oxide nanoparticles (ca. 7 nm), and their hyperthermia effect on skin cancer cells was confirmed.
  2. Front Oncol. 2021 ;11 778492
      Iron is an essential trace element for the human body, and its deficiency or excess can induce a variety of biological processes. Plenty of evidences have shown that iron metabolism is closely related to the occurrence and development of tumors. In addition, iron plays an important role in cell death, which is very important for the development of potential strategies for tumor treatment. Here, we reviewed the latest research about iron metabolism disorders in various types of tumors, the functions and properties of iron in ferroptosis and ferritinophagy, and new opportunities for iron-based on treatment methods for tumors, providing more information regarding the prevention and treatment of tumors.
    Keywords:  cancer; ferritinophagy; ferroptosis; iron; prognostic; therapy
  3. Heat Mass Transf. 2021 Nov 26. 1-11
      In this study, a more precise and cost-effective method is used for studying the drug delivery and distribution of magnetic nanoparticles in fluid hyperthermia cancer treatment, and numerical methods are employed to determine the effect of blood circulation on heat transfer and estimate the success of cancer treatment. A combination of numerical, analytical, and experimental researches is being conducted, which illustrates the essential role of numerical methods in medical and biomedical science. Magnetic NanoParticles' distribution and effects of infusion rate on the treatment are also discussed by considering the real distribution of MNPs. To increase accuracy and reduce costs in the in-vitro section, direct cutting and image processing methods are used instead of MRI. Based on the results of this section, with a tenfold increase in the infusion rate (4 μl/min to 40 μl/min), the penetration depth increases by 1 mm, which represents a nearly 17 percent increase. Concentrations of MNPs also decrease significantly at higher infusion rates. The simulations of heat transfer reveal that maximum temperatures occur at the lowest infusion rate (1.25 μl/min), and blood flow also has a significant effect on heat transfer. With an increase in the infusion rate, necrosis tissue recedes from the tumor center and approaches the border between the tumor and healthy tissue. Results also show that, in lower MNPs' concentrations, higher infusion rates result in better treatment even though minimum infusion rates are suggested to be the best rates to facilitate distribution and treatment.
  4. ACS Synth Biol. 2021 Nov 29.
      Advanced microbial therapeutics have great potential as a novel modality to diagnose and treat a wide range of diseases. Yet, to realize this potential, robust parts for regulating gene expression and consequent therapeutic activity in situ are needed. In this study, we characterized the expression level of more than 8000 variants of the Escherichia coli sigma factor 70 (σ70) promoter in a range of different environmental conditions and growth states using fluorescence-activated cell sorting and deep sequencing. Sampled conditions include aerobic and anaerobic culture in the laboratory as well as growth in several locations of the murine gastrointestinal tract. We found that σ70 promoters in E. coli generally maintain consistent expression levels across the murine gut (R2: 0.55-0.85, p value < 1 × 10-5), suggesting a limited environmental influence but a higher variability between in vitro and in vivo expression levels, highlighting the challenges of translating in vitro promoter activity to in vivo applications. Based on these data, we design the Schantzetta library, composed of eight promoters spanning a wide expression range and displaying a high degree of robustness in both laboratory and in vivo conditions (R2 = 0.98, p = 0.000827). This study provides a systematic assessment of the σ70 promoter activity in E. coli as it transits the murine gut leading to the definition of robust expression cassettes that could be a valuable tool for reliable engineering and development of advanced microbial therapeutics.
    Keywords:  engineering; flow-seq; gut; microbiota; probiotics; promoter
  5. J Appl Microbiol. 2021 Dec 03.
      AIMS: This study envisaged the isolation and characterization of magnetite nanoparticles (MNPs) from magnetotactic bacteria (MTB) and the evaluation of their antibacterial efficacy.METHODS AND RESULTS: MNPs were extracted from twenty motile but morphologically different MTB, and they were subjected to antibacterial activity assay. These MNPs were found to be highly effective against Vibrio cholerae. MTB17 was considered as the potent MTB strain based on the antibacterial activity. The MNPs of MTB17were isolated and validated by UV-Visible spectroscopy, Particle size analysis, FTIR analysis, and PXRD.
    CONCLUSIONS: Isolation and characterization of ~85 nm MNPs from MTB is reported, and it is highly active against all the gram-positive and gram-negative strains tested.
    SIGNIFICANCE AND IMPACT OF THE STUDY: This study focuses on a novel use of biogenic magnetite MNPs as an antibacterial agent, which can be further explored using in vivo studies.
    Keywords:  Magnetotactic bacteria; antibacterial activity; magnetite nanoparticles; magnetosomes; natural substance
  6. Mater Sci Eng C Mater Biol Appl. 2021 Dec;pii: S0928-4931(21)00629-9. [Epub ahead of print]131 112489
      Hydrogels have attracted much attention for biomedical and pharmaceutical applications due to the similarity of their biomimetic structure to the extracellular matrix of natural living tissues, tunable soft porous microarchitecture, superb biomechanical properties, proper biocompatibility, etc. Injectable hydrogels are an exciting type of hydrogels that can be easily injected into the target sites using needles or catheters in a minimally invasive manner. The more comfortable use, less pain, faster recovery period, lower costs, and fewer side effects make injectable hydrogels more attractive to both patients and clinicians in comparison to non-injectable hydrogels. However, it is difficult to achieve an ideal injectable hydrogel using just a single material (i.e., polymer). This challenge can be overcome by incorporating nanofillers into the polymeric matrix to engineer injectable nanocomposite hydrogels with combined or synergistic properties gained from the constituents. This work aims to critically review injectable nanocomposite hydrogels, their preparation methods, properties, functionalities, and versatile biomedical and pharmaceutical applications such as tissue engineering, drug delivery, and cancer labeling and therapy. The most common natural and synthetic polymers as matrices together with the most popular nanomaterials as reinforcements, including nanoceramics, carbon-based nanostructures, metallic nanomaterials, and various nanosized polymeric materials, are highlighted in this review.
    Keywords:  Drug delivery; In situ-forming hydrogels; Injectable hydrogels; Nanocomposite hydrogels; Stimuli-responsive polymers; Tissue engineering
  7. ACS Synth Biol. 2021 Dec 02.
      Corynebacterium glutamicum is an important workhorse in industrial white biotechnology. It has been widely applied in the producing processes of amino acids, fuels, and diverse value-added chemicals. With the continuous disclosure of genetic regulation mechanisms, various strategies and technologies of synthetic biology were used to design and construct C. glutamicum cells for biomanufacturing and bioremediation. This study mainly aimed to summarize the design and construction strategies of C. glutamicum-engineered strains, which were based on genomic modification, synthetic biological device-assisted metabolic flux optimization, and directed evolution-based engineering. Then, taking two important bioproducts (N-acetylglucosamine and hyaluronic acid) as examples, the applications of C. glutamicum cell factories were introduced. Finally, we discussed the current challenges and future development trends of C. glutamicum-engineered strain construction.
    Keywords:  Corynebacterium glutamicum; chassis cell; directed evolution; genomic modification; synthetic biology
  8. Angew Chem Int Ed Engl. 2021 Dec 01.
      Bottom-up synthetic biology is the science of building systems that mimic the structure and function of living cells from scratch. To do this, researchers combine tools from chemistry, materials science and biochemistry to develop functional and structural building blocks to construct synthetic cell-like systems. The many strategies and materials that have been developed in recent decades have enabled scientists to engineer synthetic cells and organelles that mimic essential functions and behaviors of natural cells. Examples include synthetic cells that can synthesize their own ATP using light, maintain metabolic reactions through enzymatic networks, perform gene replication, and even grow and divide. In this review, we discuss recent developments in the design and construction of synthetic cells and organelles using the bottom-up approach. Our goal is to present representative synthetic cells of increasing complexity and strategies for solving distinct challenges in bottom-up synthetic biology.
    Keywords:  Synthetic biology; artificial cells; artificial organelles; cell mimics; microreactors
  9. Nat Commun. 2021 Nov 29. 12(1): 6957
      Gene expression noise can reduce cellular fitness or facilitate processes such as alternative metabolism, antibiotic resistance, and differentiation. Unfortunately, efforts to study the impacts of noise have been hampered by a scaling relationship between noise and expression level from individual promoters. Here, we use theory to demonstrate that mean and noise can be controlled independently by expressing two copies of a gene from separate inducible promoters in the same cell. We engineer low and high noise inducible promoters to validate this result in Escherichia coli, and develop a model that predicts the experimental distributions. Finally, we use our method to reveal that the response of a promoter to a repressor is less sensitive with higher repressor noise and explain this result using a law from probability theory. Our approach can be applied to investigate the effects of noise on diverse biological pathways or program cellular heterogeneity for synthetic biology applications.