Microscopy Research and Technique最新文献

Scanning electron microscope (SEM) can observe bacterial morphology with nanoscale spatial resolution and is therefore used to investigate the action mechanisms of disinfectants. Since the structural changes that show antibacterial effects are extremely subtle, reliable specimen preparation is necessary to maintain and observe these traces. In this study, we demonstrated the fixation and drying conditions necessary to observe the effects of disinfectants on bacteria using SEM. In the double fixation of specimens, osmium tetroxide, which fixes lipids, did not appear to affect the SEM observation of the Escherichia coli surface, mainly composed of lipopolysaccharides, under our experimental conditions. Hexamethyldisilazane (HMDS), used to dry the specimens, retained a fine structure comparable to conventional freeze-drying methods without special equipment. Furthermore, shrinkage deformation due to drying was significantly suppressed in two of the three conditions tested compared to freeze-drying. When E. coli was treated with two types of disinfectant, benzalkonium chloride (BAC) and chlorhexidine gluconate (CHG), for 5 min, the number of viable bacteria fell below the detection limit. When E. coli collected from these bacterial suspensions was dried with HMDS, the two disinfectants roughened the bacterial surface. In some BAC-treated bacteria, membrane fusion was observed between adjacent bacteria. Pit structures were observed in the CHG-treated bacteria. These morphological changes, which indicate the effectiveness of the disinfectants, were consistent with the results of observations of the freeze-dried specimens used as a control test. These results suggest that chemical drying with HMDS can quickly and efficiently provide morphological information to understand how disinfectants cause deformation and affect bacterial function.

The disposal of coffee cherry pulping wastewater (CPWW) poses severe environmental risks, including water body eutrophication, soil acidification, and toxicity to aquatic life due to its high organic load (COD: 29,450 mg/L; BOD5: 16,500 mg/L), acidic pH (4.8), and elevated solids (TDS: 3240 mg/L; TSS: 4540 mg/L). To address this, we synthesized iron oxide nanoparticles from Ricinus communis L. seed extract via a green method and evaluated their efficacy in CPWW treatment. Characterization by XRD, SEM, and FTIR confirmed the formation of the nanoparticles stabilized by phytochemicals, with functional groups such as hydroxyl (OH) and amine (NH) critical for pollutant binding. At an optimal dosage of 0.08 g/100 mL, the nanoparticles achieved 74% COD removal, 69% TDS reduction, and 92% decolorization, significantly mitigating the pollutant load of the effluent, thereby minimizing risks to aquatic ecosystems and soil health. Furthermore, FTIR analysis of the treated sludge revealed the potential functional groups facilitating pollutant removal. This study highlights the dual environmental benefit of green-synthesized iron oxide nanoparticles: (1) a sustainable synthesis route avoiding toxic chemicals, and (2) high-efficiency pollutant removal, offering a scalable solution for coffee-processing industries to minimize their ecological footprint. By addressing the dual challenges of waste toxicity and treatment sustainability, this approach aligns with circular economy principles, promoting cleaner production in agro-industrial sectors.

In recent times, green-synthesized nanoparticles have been widely used in the biomedical field due to their low toxicity, eco-friendliness, cost-effectiveness, and enhanced therapeutic potential. This study investigated the anticancer, antibacterial, and antibiofilm properties of green-synthesized manganese dioxide nanoparticles derived from Artemisia pallens (AP-MnNPs). The AP-MnNPs were characterized through various techniques, including UV–Vis spectroscopy, SEM, EDX, XRD, and FTIR. These nanoparticles effectively inhibited the growth of cancer cell lines A431, A549, and MCF7, with the highest inhibition observed in A431 cells (IC₅₀ = 25 μg/mL). In A431 cells, AP-MnNPs induced ROS generation, mitochondrial disruption, arrested cell cycle progression at the G2/M phase, DNA breakage, and programmed cell death. AP-MnNPs also modulated apoptotic markers by increasing the expression of pro-apoptotic proteins (Bax, caspase 3) and decreasing the anti-apoptotic protein Bcl-2, thereby disrupting cell proliferation via suppression of the PI3K/Akt signaling pathway. Furthermore, AP-MnNPs demonstrated antibacterial and antibiofilm efficacy against Pseudomonas aeruginosa , Streptococcus mutans , Staphylococcus aureus , and their mixed cultures. Collectively, AP-MnNPs exhibit promising potential as anticancer agents that impede cancer cell growth and modulate proliferation-related signaling proteins, as well as antibacterial and antibiofilm agents.

Understanding meiotic behavior and pollen biology is crucial for effective conservation of plant species. This study presents the first detailed analysis of meiotic behavior and its correlation with pollen fertility and seed set in Phytolacca acinosa Roxb., a multipurpose medicinal herb native to the Himalaya. The flower buds were collected from two selected sites in the Kashmir Himalaya, India. In this study, we used the squash technique, in which anthers were squashed in 2% acetocarmine, and the slides were observed under a microscope to assess chromosome number and meiotic behavior. The species exhibited a chromosome count of 2n = 8x = 72. Most pollen mother cells (PMCs) (74%–79%) underwent normal meiosis; however, 21%–26% PMCs exhibited abnormalities, including chromosome stickiness, chromosomal bridges, laggards, un-oriented bivalents, and micronuclei. Chromosome stickiness was the most prominent meiotic abnormality, followed by laggard and bridge formation. These meiotic irregularities significantly reduced pollen fertility (75.45%–77.57%), fruit set (73.22%–75.67%), and seed set (71.1%–72.14%) across both selected sites. The findings highlight meiotic irregularities as a potential reproductive constraint, emphasizing the need for conservation measures to ensure the sustainable utilization of this medicinally important plant species. Future studies should investigate the genetic and environmental factors underlying these meiotic disturbances.

Herein, we adapted a quick, cost-effective, and environmentally friendly biological method for the synthesis of Ag-NPs using silver nitrate solution as a precursor, and the aqueous leaf extract of Lespedeza juncea (Chinese lespedeza) was exploited to synthesize Ag-NPs. Various physiochemical characterization techniques were used to characterize the nanoparticles. The UV spectrum revealed a resonance absorption peak at 428 nm, indicating successful synthesis of the nanoparticles. The EDX results indicated the presence of Ag, C, O, and Cl elements in biosynthesized Ag-NPs with elemental compositions of 53.93%, 32.34%, 12.49%, and 1.23%, respectively. The XRD analysis displayed the crystalline nature of the nanoparticles with a face-centered cubic lattice. The FTIR spectrum confirmed the involvement of plant-based biological compounds as reducing and capping agents. TEM revealed quasi-spherical Ag-NPs of 50 nm or smaller in size. An insight into its biological activities reveals significant antimicrobial activities against Staphylococcus aureus (14.1 ± 0.76 mm), Pseudomonas aeruginosa (11.50 ± 0.40 mm), Escherichia coli (16 ± 0.95 mm), and the fungal strains, viz. Candida albicans (14 ± 0.80 mm), Aspergillus flavus (16.50 ± 0.50 mm), Aspergillus niger (17 ± 0.86 mm) and afflicted 75% mortality to Caenorhabditis elegans. Furthermore, the Ag-NPs were found to be potent inhibitors of the enzymes tyrosinase, urease, acetylcholinesterase, and butyrylcholinesterase with IC₅₀ values of 14.3 ± 0.2, 19.5 ± 1.1, 9.3 ± 1.3, and 32.65 ± 1.9 μg/mL, respectively. The overall outcome of the study suggests that L. juncea mediated synthesized Ag-NPs hold the potential to be employed as a promising tool for their antibacterial, antifungal, nematocidal, and for a variety of enzymes inhibitory activities.

Focused ion beam-scanning electron microscopy (FIB-SEM) is a microscopy technique that can be used to investigate the quality and structural properties of industrial materials such as polyolefins. An understudied aspect and possible drawback of the technique could be the implantation of the impinging ions under the sample surface and damage to the molecular structure, hindering its use as a sample preparation tool for surface-sensitive techniques. We systematically investigated the damaging effects of gallium liquid metal focused ion beam under grazing incident beam angle and various accelerating voltages on polyethylene. Changes in molecular structure and ion implantation depth were analyzed with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) depth profiling and optical profilometry. Our results show that the gallium ion beam causes significant damage to the polyolefin structure, which is especially observed as dehydrogenation of the molecular structure of the (sub)surface. These molecular products are concentrated in distinct sub-surface zones, where damage is coupled to the presence of implanted gallium from the FIB etching.

The current study aims to compare the morphological features of the oropharyngeal roof of the little owl ( Athene noctua ) and the domestic pigeon ( Columba livia domestica) by gross anatomy, morphometric measurements, scanning electron microscopy, and light microscopy. Ten heads of normal, healthy, and adult little owls and domestic pigeons were used in the current study as follows: seven heads for gross anatomical examination and light microscopy, and three for scanning electron microscopy. The oropharyngeal roof had a triangular appearance in both birds, was enlarged and broad in the little owl, and narrowly elongated in the domestic pigeon. The little owl had a median longitudinal ridge, a transverse ridge, and two lateral longitudinal ridges, while the domestic pigeon had one median and two lateral ridges. The choanal slit in both birds was composed of rostrally narrow and caudally wide parts. In the little owl, the edges of both parts were encircled by papillae, while in the domestic pigeon, the papillae encircled the edges of the rostral part only. The surface of the pharyngeal roof in the little owl had numerous elongated conical pharyngeal papillae, while that of the domestic pigeon was devoid of papillae. The edges of the infundibular cleft in the little owl had prominent large conical papillae, while those in the pigeon were devoid of papillae. Histologically, the epithelium of the plate and pharynx of both birds was composed of stratified squamous epithelium. In conclusion, the present study clarified several differences between the oropharyngeal roof of the little owl and the domestic pigeon, which reflect their adaptation to their feeding habits and the surrounding environments.