Sareh Arjmand

Carbon quantum dots (CQDs) have emerged as eco-friendly nanomaterials with tunable optical properties and biomedical potential. This study aimed to synthesize and characterize phosphorus-doped CQDs from Saccharomyces cerevisiae β-glucan, providing a green, reproducible production route and assessing their physicochemical and biological properties. β-Glucan extracted from yeast cell wall (YCW) was hydrothermally carbonized at 250 °C to yield fluorescent CQDs. Structural, optical, and compositional analyses were conducted using FTIR, XRD, EDX-MAP, TEM, and DLS. The antibacterial, antioxidant, anti-inflammatory, and cytotoxic properties were systematically evaluated using standard in vitro assays. The synthesized CQDs exhibited strong π–π* absorption at 201 nm and pH-sensitive blue photoluminescence with a 24% quantum yield, and TEM confirmed core sizes below 10 nm. The CQDs displayed broad-spectrum antibacterial activity, exceeding ciprofloxacin against resistant Pseudomonas aeruginosa, with MIC and MBC values ranging from 0.93 to 3.75 mg mL⁻¹. They also showed high antioxidant activity under acidic conditions and reduced erythrocyte sedimentation rate from 12 mm h⁻¹ to 1 mm h⁻¹, indicating anti-inflammatory potential. Cell viability remained above 70% at ~ 47 µg mL⁻¹, confirming acceptable biocompatibility. β-Glucan-derived CQDs offer sustainable synthesis, strong optical properties, and multifunctional bioactivity, creating an eco-friendly nanomaterial for antimicrobial, antioxidant, and inflammation-responsive uses.

Mitochondrial DNA (mtDNA) copy number and telomere length are widely recognized as biomarkers of cellular aging and metabolic health. This study aimed to investigate the relationships between BMI, exercise modality, mtDNA copy number, and telomere length using saliva samples from Iranian adults. Participants ( n = 96) were categorized into four groups: endurance athletes, strength athletes, overweight/obese individuals (BMI > 25), and healthy controls (BMI 18–25). Saliva samples were collected for DNA extraction, and mtDNA copy number and telomere length were quantified using real‐time PCR. Statistical analyses included Kruskal–Wallis and Dunnett's post hoc tests, as well as linear regression to assess correlations among variables. The results indicated that endurance athletes exhibited a significantly higher mtDNA copy number compared to controls and strength athletes, reflecting enhanced mitochondrial biogenesis from aerobic training. No significant differences in telomere length were observed among groups. While BMI showed no significant correlation with telomere length or mtDNA copy number overall, a significant negative correlation between mtDNA copy number and BMI was found exclusively in endurance athletes. Additionally, a strong positive correlation between mtDNA copy number and telomere length was observed in all groups except strength athletes. No significant differences were found between saliva and blood samples for either biomarker, and women demonstrated longer telomeres than men. This study highlights the positive impact of endurance exercise on mitochondrial biogenesis while revealing complex relationships between BMI, exercise modality, and cellular aging biomarkers. These findings offer insights into exercise‐specific effects on cellular aging.

Nanofibers show promise for wound healing by facilitating active agent delivery, moisture retention, and tissue regeneration. However, selecting suitable dressings for diverse wound types and managing varying exudate levels remains challenging. This study synthesized carbon quantum dots (CQDs) from citrate salt and thiourea using a hydrothermal method. The CQDs displayed antibacterial activity against Staphylococcus aureus and Escherichia coli. A nanoscaffold comprising gelatin, chitosan, and polycaprolactone (GCP) was synthesized and enhanced with silver nanoparticle-coated CQDs (Ag-CQDs) to form GCP-Q, while citrate addition yielded GCP-QC. Multiple analytical techniques, including electron microscopy, FT-IR spectroscopy, dynamic light scattering, UV–Vis, photoluminescence, X-ray diffraction, porosity, degradability, contact angle, and histopathology assessments characterized the CQDs and nanofibers. Integration of CQDs and citrate into the GCP nanofibers increased porosity, hydrophilicity, and degradability—properties favorable for wound healing. Hematoxylin and eosin staining showed accelerated wound closure with GCP-Q and GCP-QC compared to GCP alone. Overall, GCP-Q and GCP-QC nanofibers exhibit significant potential for skin tissue engineering applications.

This chapter reviews the different promoters used to control gene expression in the yeast Pichia pastoris, mainly for recombinant protein production. It covers natural inducible, derepressed, and constitutive promoters, as well as engineered synthetic/hybrid promoters, orthologous promoters from related yeasts, and emerging bidirectional promoters. Key examples, characteristics, and regulatory mechanisms are discussed for each promoter class. Recent efforts in promoter engineering through rational design, mutagenesis, and computational approaches are also highlighted. Looking ahead, we anticipate further developments that will enhance promoter design for Pichia pastoris. Overall, this comprehensive overview underscores the importance of promoter choice and engineering for fully harnessing Pichia pastoris biotechnological potential.

Recombinant proteins are essential in various industries, and scientists employ genetic engineering and synthetic biology to enhance the host cell’s protein production capacity. Stress response pathways have been found effective in augmenting protein secretion. Cold atmospheric pressure plasma (CAP) can induce oxidative stress and enhance protein production. Previous studies have confirmed the applicability of CAP jets on Phytase and green fluorescent protein (GFP) production in Pichia pastoris hosts. This study investigates the effect of CAP treatment on another valuable recombinant protein, Endoglucanase II (EgII), integrated into the Pichia pastoris genome. The results demonstrated that plasma induction via two different ignition modes: sinusoidal alternating current (AC) and pulsed direct current (DC) for 120, 180, and 240 s has boosted protein secretion without affecting cell growth and viability. The AC-driven jet exhibited a higher percentage increase in secretion, up to 45%. Simulation of plasma function using COMSOL software provided a pattern of electron temperature (T_e) and density distribution, which determine the plasma cocktail’s chemistry and reactive species production. Furthermore, electron density (n_e) and temperature were estimated from the recorded optical spectrum. The difference in electron properties may explain the moderately different impressions on expression capability. However, cell engineering to improve secretion often remains a trial-and-error approach, and improvements are, at least partially, specific to the protein produced.

Cold atmospheric pressure plasma (CAP) has been described as a novel technology with expanding applications in biomedicine and biotechnology. In the present study, we provide a mildly stressful condition using non-lethal doses of CAP (120, 180, and 240 s) and evaluate its potential benefits on the recombinant production of a model protein (enhanced green fluorescent protein (eGFP)) in yeast Pichia pastoris. The measured eGFP fluorescence augmented proportional to CAP exposure time. After 240 s treatment with CAP, the measured fluorescent intensity of culture supernatant (after 72 h) and results of real-time PCR (after 24 h) indicated an 84% and 76% increase in activity and related RNA concentration, respectively. Real-time analysis of a list of genes involved in oxidative stress response revealed a significant and durable improvement in their expression at five h and 24 h following CAP exposure. The improvement of the recombinant model protein production may be partly explained by the impact of the RONS on cellular constituents and altering the expression of specific stress genes. In conclusion, using CAP strategy may be considered a valuable strategy to improve recombinant protein production, and deciphering the molecular background mechanism could be inspiring in the reverse metabolic engineering of host cells.

Background Reprogramming in transcriptional regulation provides an effective tool for adjusting cellular metabolic activities. The strong methanol-inducible alcohol oxidase-1 promoter (pAOX1) is commonly used for heterologous gene expression in the yeast Pichia pastoris. Here, we present a novel Pichia pastoris strain engineered to co-express methanol-induced transcription factor 1 (Mit1) and the target protein. Mit1 upregulates pAOX1 in response to methanol. Methods and Results Two model proteins (VEGF and eGFP) have been used as the target proteins under the control of pAOX1. The sequence of Mit1 had obtained from the yeast genome and likewise cloned under the control of pAOX1. The results indicated a 1.9 and 2.2 fold increase in the detected VEGF and eGFP, respectively, when co-expressed with Mit1. Furthermore, the double-recombinant cells, containing Mit-1 and eGFP, produced 1.3 fold more eGFP when the methanol feeding concentration was doubled. The real-time PCR indicated a slight increase in the Mit1 expression, probably due to the negative regulatory feedback loop that exists for the intrinsic yeast Mit1. Overexpression of Mit1 also led to duplication of AOX1 enzyme activity, which may enhance the yeast cells’ capacity for methanol detoxification. Conclusion Overexpression of Mit1 could be considered a promising strategy for upregulation of target recombinant proteins in Pichia pastoris. Graphical Abstract Intracellular overexpression of Mit1 upregulates the heterologous target gene (eGFP) production, which is expressed under the control of pAOX1.