Nanometrology and its perspectives in environmental research

Analysis of TEM micrographs with deep learning reveals APOE genotype-specific associations between HDL particle diameter and Alzheimer's dementia

High-density lipoprotein (HDL) particle diameter distribution is informative in the diagnosis of many conditions, including Alzheimer's disease (AD). However, obtaining an accurate HDL size measurement is challenging. We demonstrated the utility of measuring the diameter of more than 1,800,000 HDL particles with the deep learning model YOLOv7 (you only look once) from micrographs of 183 HDL samples, including patients with dementia or normal cognition (controls). This method was shown to be more efficient and accurate than conventional image analysis software. Using this method, we found a higher abundance of small HDLs in participants with dementia compared to controls in patients with the apolipoprotein E (APOE) ε3ε4 genotype, whereas patients with the APOE ε3ε3 genotype had higher variability in the abundance of different HDL subclasses. Our results show an example of accurate individual HDL particle diameter measurement for large-scale clinical samples, which can be expanded to characterize the relationship between disease risk and other nanoparticles in the sub-20-nm diameter size range.

Utilization of Ziziphus spina-christi leaf extract-loaded chitosan nanoparticles in wastewater treatment and their impact on animal health

Ziziphus leaf extract (ZEX), chitosan nanoparticles (CS NPs) and Ziziphus leaf extract loaded chitosan nanoparticles (ZEX-CS NPs) were prepared in this study and after chemical analysis and characterization, they were used in wastewater purification. The study also aimed to establish, using an animal model, the feasibility of employing treated water in drinking applications. ZEX-CS NPs were prepared by ionic gelation method. About 25 male Sprague Dawley rats (10 weeks and 170-200 g) were divided into five groups (5 rats/group): group I received tape water; group II received untreated wastewater, group III received ZEX treated wastewater, group IV received CS NPs treated wastewater and group V received ZEX-CS NPs treated wastewater. ZEX-CS NPs have a size of 73 nm, hydrodynamic size of 85.81 nm and zeta potential of -33.68 mV. In addition, ZEX-CS NPs have stronger antioxidant and anti-inflammatory activity with moderate anti-coagulant activity and weaker cytotoxicity than ZEX and CS NPs. Group II showed a significant elevation in the kidney function parameters, oxidative stress and cytokine levels when compared to the other groups, in addition; no significant differences were found in all measured parameters between the rats of group I and V. ZEX-CS NPs were effective in wastewater purification.

Eobania vermiculata whole-body muscle extract-loaded chitosan nanoparticles enhanced skin regeneration and decreased pro-inflammatory cytokines in vivo

BACKGROUND

Usually, wounds recover in four to six weeks. Wounds that take longer time than this to heal are referred to as chronic wounds. Impaired healing can be caused by several circumstances like hypoxia, microbial colonization, deficiency of blood flow, reperfusion damage, abnormal cellular reaction and deficiencies in collagen production. Treatment of wounds can be enhanced through systemic injection of the antibacterial drugs and/or other topical applications of medications. However, there are a number of disadvantages to these techniques, including the limited or insufficient medication penetration into the underlying skin tissue and the development of bacterial resistance with repeated antibiotic treatment. One of the more recent treatment options may involve using nanotherapeutics in combination with naturally occurring biological components, such as snail extracts (SE). In this investigation, chitosan nanoparticles (CS NPs) were loaded with an Eobania vermiculata whole-body muscle extract. The safety of the synthesized NPs was investigated in vitro to determine if these NPs might be utilized to treat full-skin induced wounds in vivo.

RESULTS

SEM and TEM images showed uniformly distributed, spherical, smooth prepared CS NPs and snail extract-loaded chitosan nanoparticles (SE-CS NPs) with size ranges of 76-81 and 91-95 nm, respectively. The zeta potential of the synthesized SE-CS NPs was - 24.5 mV, while that of the CS NPs was 25 mV. SE-CS NPs showed a remarkable, in vitro, antioxidant, anti-inflammatory and antimicrobial activities. Successfully, SE-CS NPs (50 mg/kg) reduced the oxidative stress marker (malondialdehyde), reduced inflammation, increased the levels of the antioxidant enzymes (superoxide dismutase and glutathione), and assisted the healing of induced wounds. SE-CS NPs (50 mg/kg) can be recommended to treat induced wounds safely. SE was composed of a collection of several wound healing bioactive components [fatty acids, amino acids, minerals and vitamins) that were loaded on CS NPs.

CONCLUSIONS

The nanostructure enabled bioactive SE components to pass through cell membranes and exhibit their antioxidant and anti-inflammatory actions, accelerating the healing process of wounds. Finally, it is advised to treat rats' wounds with SE-CS NPs.

Measuring nanoparticles in liquid with attogram resolution using a microfabricated glass suspended microchannel resonator

The use of nanoparticles has been growing in various industrial fields, and concerns about their effects on health and the environment have been increasing. Hence, characterization techniques for nanoparticles are essential. Here, we present a silicon dioxide microfabricated suspended microchannel resonator (SMR) to measure the mass and concentration of nanoparticles in a liquid as they flow. We measured the mass detection limits of the device using laser Doppler vibrometry. This limit reached a minimum of 377 ag that correspond to a 34 nm diameter gold nanoparticle or a 243 nm diameter polystyrene particle, when sampled every 30 ms. We compared the fundamental limits of the measured data with an ideal noiseless measurement of the SMR. Finally, we measured the buoyant mass of gold nanoparticles in real-time as they flowed through the SMR.

Suspended Nanochannel Resonator Arrays with Piezoresistive Sensors for High-Throughput Weighing of Nanoparticles in Solution

As the use of nanoparticles is expanding in many industrial sectors, pharmaceuticals, cosmetics among others, flow-through characterization techniques are often required for in-line metrology. Among the parameters of interest, the concentration and mass of nanoparticles can be informative for yield, aggregates formation or even compliance with regulation. The Suspended Nanochannel Resonator (SNR) can offer mass resolution down to the attogram scale precision in a flow-through format. However, since the readout has been based on the optical lever, operating more than a single resonator at a time has been challenging. Here we present a new architecture of SNR devices with piezoresistive sensors that allows simultaneous readout from multiple resonators. To enable this architecture, we push the limits of nanofabrication to create implanted piezoresistors of nanoscale thickness (∼100 nm) and implement an algorithm for designing SNRs with dimensions optimized for maintaining attogram scale precision. Using 8-in. processing technology, we fabricate parallel array SNR devices which contain ten resonators. While maintaining a precision similar to that of the optical lever, we demonstrate a throughput of 40 000 particles per hour-an order of magnitude improvement over a single device with an analogous flow rate. Finally, we show the capability of the SNR array device for measuring polydisperse solutions of gold particles ranging from 20 to 80 nm in diameter. We envision that SNR array devices will open up new possibilities for nanoscale metrology by measuring not only synthetic but also biological nanoparticles such as exosomes and viruses.

Application of Organic-Inorganic Hybrids in Chemical Analysis, Bio- and Environmental Monitoring

Organic-inorganic hybrids (OIH) are considered to be a powerful platform for applications in many research and industrial fields. This review highlights the application of OIH for chemical analysis, biosensors, and environmental monitoring. A methodology toward metrological traceability measurement and standardization of OIH and demonstration of the role of mathematical modeling in biosensor design are also presented. The importance of the development of novel types of OIH for biosensing applications is highlighted. Finally, current trends in nanometrology and nanobiosensors are presented.

Magnetic hyperthermia of breast cancer cells and MRI relaxometry with dendrimer-coated iron-oxide nanoparticles

BACKGROUND

Recently, some studies have focused on dendrimer nanopolymers as a magnetic resonance imaging (MRI) contrast agent or a vehicle for gene and drug delivery. Considering the suitable properties of these materials, they are appropriate candidates for coating iron-oxide nanoparticles which are applied in magnetic hyperthermia. To the best of our knowledge, the novelty of this study is the investigation of fourth-generation dendrimer-coated iron-oxide nanoparticles (G4@IONPs) in magnetic hyperthermia and MRI.

METHODS

IONPs were synthesized via co-precipitation and coated with the fourth generation (G4) of polyamidoamine dendrimer. The cytotoxicity of G4@IONPs with different concentrations was assessed in a human breast cancer cell line (MCF7) and human fibroblast cell line (HDF1). Hemolysis and stability of G4@IONPs were investigated, and in addition, the interaction of these particles with MCF7 cells was assessed by Prussian blue staining. Heat generation and specific absorption rate (SAR) were calculated from measurement and simulation results at 200 and 300 kHz. MCF7 and HDF1 cells were incubated with G4@IONPs for 2 h and then put into the magnetic coil for 120 min. Relaxometry experiments were performed with different concentrations of G4@IONPs with T1- and T2-weighted MR images.

RESULTS

The TEM results showed that G4@IONPs were 10 ± 4 nm. The in vitro toxicity assessments showed that synthesized nanoparticles had low toxicity. The viability of MCF7 cells incubated with G4@IONPs decreased significantly after magnetic hyperthermia. In addition, MR imaging revealed that G4@IONPs improved transverse relaxivity (r2) significantly.

CONCLUSIONS

Our results encouraged the future application of G4@IONPs in magnetic hyperthermia and MR imaging.

Biodistribution, pharmacokinetics, and toxicity of dendrimer-coated iron oxide nanoparticles in BALB/c mice

Background

The possibility of using a specific nanoparticle in nanomedicine highly depends on its biodistribution profile and biocompatibility. Due to growing demand for iron oxide nanoparticles (IONPs) and dendrimers in biomedical applications, this study was performed to assess the biodistribution, pharmacokinetics, and toxicity of dendrimer-coated iron oxide nanoparticles (G₄@IONPs).

Materials and methods

IONPs were synthesized via co-precipitation and coated with the fourth generation (G₄) of polyamidoamine (PAMAM) dendrimer. To determine the biodistribution, 5 mg/mL G₄@IONPs suspension was intraperitoneally injected into tumor-bearing BALB/c mice, and iron levels in blood and various organs, including the lung, liver, brain, heart, tumor, and kidney, were measured by inductively coupled plasma mass spectrometry (ICP-MS) at 4, 8, 12, and 24 h after injection. Also, to investigate the toxicity of G₄@IONPs, different concentrations of G₄@IONPs were injected into BALB/c mice, and blood, renal, and hepatic factors were measured. Furthermore, histopathological staining was performed to investigate the effect of G₄@IONPs on the liver and kidney tissues.

Results

The results showed that the iron content was higher in the kidney, liver, and lung tissues 24 h after injection. Toxicity assessments revealed a significant increase in blood urea nitrogen (BUN) and direct bilirubin at the concentration of 10 mg/kg. Also, in this concentration, histopathological abnormalities were detected in liver tissue.

Conclusion

Although more systematic studies are still required, our results encouraged the future investigations of G₄@IONPs in biomedical applications.