Diamond Relaxometry as a Tool to Investigate the Free Radical Dialogue between Macrophages and Bacteria

Macrophage-Inspired marine antifouling coating with dynamic surfaces based on regulation of dynamic covalent bonds

Macrophages can kill bacteria and viruses by releasing free radicals, which provides a possible approach to construct antifouling coatings with dynamic surfaces that release free radicals if the breaking of dynamic covalent bonds is precisely regulated. Herein, inspired by the defensive behavior of macrophages of releasing free radicals to kill bacteria and viruses, a marine antifouling coating composed of polyurethane incorporating dimethylglyoxime (PUx-DMG) is prepared by precise regulation of dynamic oxime-urethane covalent bonds. The obtained alkyl radical (R·) derived from the cleavage of the oxime-urethane bonds manages to effectively suppress the attachment of marine biofouling. Moreover, the intrinsic dynamic surface makes it difficult for biofouling to adhere and ultimately achieves sustainable antifouling property. Notably, the PU50-DMG coating not only presents efficient antibacterial and antialgae properties, but also prevents macroorganisms from settling in the sea for up to 4 months. This provides a pioneer broad-spectrum strategy to explore the marine antifouling coatings.

Advances in biosensors for major depressive disorder diagnostic biomarkers

Depression is one of the most common mental disorders and is mainly characterized by low mood or lack of interest and pleasure. It can be accompanied by varying degrees of cognitive and behavioral changes and may lead to suicide risk in severe cases. Due to the subjectivity of diagnostic methods and the complexity of patients' conditions, the diagnosis of major depressive disorder (MDD) has always been a difficult problem in psychiatry. With the discovery of more diagnostic biomarkers associated with MDD in recent years, especially emerging non-coding RNAs (ncRNAs), it is possible to quantify the condition of patients with mental illness based on biomarker levels. Point-of-care biosensors have emerged due to their advantages of convenient sampling, rapid detection, miniaturization, and portability. After summarizing the pathogenesis of MDD, representative biomarkers, including proteins, hormones, and RNAs, are discussed. Furthermore, we analyzed recent advances in biosensors for detecting various types of biomarkers of MDD, highlighting representative electrochemical sensors. Future trends in terms of new biomarkers, new sample processing methods, and new detection modalities are expected to provide a complete reference for psychiatrists and biomedical engineers.

Quantum-enhanced diamond molecular tension microscopy for quantifying cellular forces

The constant interplay and information exchange between cells and the microenvironment are essential to their survival and ability to execute biological functions. To date, a few leading technologies such as traction force microscopy, optical/magnetic tweezers, and molecular tension-based fluorescence microscopy are broadly used in measuring cellular forces. However, the considerable limitations, regarding the sensitivity and ambiguities in data interpretation, are hindering our thorough understanding of mechanobiology. Here, we propose an innovative approach, namely, quantum-enhanced diamond molecular tension microscopy (QDMTM), to precisely quantify the integrin-based cell adhesive forces. Specifically, we construct a force-sensing platform by conjugating the magnetic nanotags labeled, force-responsive polymer to the surface of a diamond membrane containing nitrogen-vacancy centers. Notably, the cellular forces will be converted into detectable magnetic variations in QDMTM. After careful validation, we achieved the quantitative cellular force mapping by correlating measurement with the established theoretical model. We anticipate our method can be routinely used in studies like cell-cell or cell-material interactions and mechanotransduction.

Quantum Sensing of Free Radicals in Primary Human Granulosa Cells with Nanoscale Resolution

Cumulus granulosa cells (cGCs) and mural granulosa cells (mGCs), although derived from the same precursors, are anatomically and functionally heterogeneous. They are critical for female fertility by supporting oocyte competence and follicular development. There are various techniques used to investigate the role of free radicals in mGCs and cCGs. Yet, temporospatial resolution remains a challenge. We used a quantum sensing approach to study free radical generation at nanoscale in cGCs and mGCs isolated from women undergoing oocyte retrieval during in vitro fertilization (IVF). Cells were incubated with bare fluorescent nanodiamonds (FNDs) or mitochondria targeted FNDs to detect free radicals in the cytoplasm and mitochondria. After inducing oxidative stress with menadione, we continued to detect free radical generation for 30 min. We observed an increase in free radical generation in cGCs and mGCs from 10 min on. Although cytoplasmic and mitochondrial free radical levels are indistinguishable in the physiological state in both cGCs and mGCs, the free radical changes measured in mitochondria were significantly larger in both cell types, suggesting mitochondria are sites of free radical generation. Furthermore, we observed later occurrence and a smaller percentage of cytoplasmic free radical change in cGCs, indicating that cGCs may be more resistant to oxidative stress.

Quantum Sensing for Real-Time Monitoring of Drug Efficacy in Synovial Fluid from Arthritis Patients

Diamond-based T1 relaxometry is a new technique that allows nanoscale magnetic resonance measurements. Here we present its first application in patient samples. More specifically, we demonstrate that relaxometry can determine the free radical load in samples from arthritis patients. We found that we can clearly differentiate between osteoarthritis and rheumatoid arthritis patients in both the synovial fluid itself and cells derived from it. Furthermore, we tested how synovial fluid and its cells respond to piroxicam, a common nonsteroidal anti-inflammatory drug (NSAID). It is known that this drug leads to a reduction in reactive oxygen species production in fibroblast-like synoviocytes (FLS). Here, we investigated the formation of free radicals specifically. While FLS from osteoarthritis patients showed a drastic decrease in the free radical load, cells from rheumatoid arthritis retained a similar radical load after treatment. This offers a possible explanation for why piroxicam is more beneficial for patients with osteoarthritis than those with rheumatoid arthritis.

Fluorescent Nanodiamonds for Tracking Single Polymer Particles in Cells and Tissues

Polymer nanoparticles are widely used in drug delivery and are also a potential concern due to the increased burden of nano- or microplastics in the environment. In order to use polymer nanoparticles safely and understand their mechanism of action, it is useful to know where within cells and tissues they end up. To this end, we labeled polymer nanoparticles with nanodiamond particles. More specifically, we have embedded nanodiamond particles in the polymer particles and characterized the composites. Compared to conventional fluorescent dyes, these labels have the advantage that nanodiamonds do not bleach or blink, thus allowing long-term imaging and tracking of polymer particles. We have demonstrated this principle both in cells and entire liver tissues.

An Evaluation of Antibacterial Effects of Human Amniotic Fluid on Pathogenic and Probiotic Bacteria In Vitro

Background

Amniotic fluid in the uterus is beneficial for the fetus growth and protection due to its nutritional elements as well as its antibacterial and anti-inflammatory properties. Today, body membranes are increasingly being used in multiple fields. The purpose of the current study was evaluation of the antibacterial effects of amniotic fluid and comparison of its effects on pathogenic and probiotic bacteria.

Methods

This experimental study was conducted on amniotic fluid obtained from 43 healthy mothers who gave birth by selective cesarean section. Then, antibacterial effects of amniotic fluids were investigated on 8 standard bacterial strains, including Bacillus cereus, Escherichia coli, Staphylococcus aureus, Shigella flexneri, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus cereus, and Lactobacillus plantarum by agar well-diffusion method. Data analysis was performed by SPSS software, vs. 22 (IBM, US).

Results

Amniotic fluid revealed an inhibitory effect on the growth of bacterial strains. Staphylococcus aureus and Streptococcus pyogenes strains showed growth inhibition in 39% and 17% of samples, respectively. In other bacterial strains, there was growth inhibition in less than 5% of the samples. Also, the zone of growth inhibition for Staphylococcus aureus and Streptococcus pyogenes was significantly higher than the other strains. Amniotic fluid samples had an antibacterial effect on all pathogen strains in general, but not on the Lactobacillus plantarum probiotic strain.

Conclusion

Our findings suggest that the antibacterial effect of amniotic fluid on pathogenic bacteria is significantly higher than the Lactobacillus plantarum as a probiotic one. Overall, the findings support the use of natural substances as alternative therapeutic agents to combat antibiotic resistance.