Gram-negative Research Articles

New chitosan schiff base-modified ferrite: Mechanistic insights and performance enhancement in photocatalysis and antibacterial applications

Harnessing biocompatibility and magnetic separability a Chitosan Schiff base-modified ferrite is an innovative approach for addressing the issue of environmental pollution. This study aims to use a new visible light-activated photocatalyst made of cobalt ferrite (CoFe) anchored with Chitosan Schiff Base (CSB) to examine Rhodamine B (RhB) photodegradation. CSB@CoFe composite was synthesized using hydrothermal and sol-gel methods. This modified CSB composite and oxygen vacancies (OVs) have been proven by X-ray photoelectron spectroscopy, experimental calculations, and radical capture tests. The process of oxidative degradation is facilitated by radicals such as hydroxyl (OH•) and superoxide (O2•−), as evidenced by research utilizing reactive species capture. The CSB@CoFe photocatalyst degraded 94.5 % of Rhodamine B (RhB, 50 mg/L) in 60 min at pH 7 and 1.0 g/L. The CSB@CoFe heterostructure outperformed CSB against Gram-positive and Gram-negative bacteria. The photocatalyst exhibited exceptional stability across the five cycles. This study shows CSB@CoFe's persistent photocatalytic ability to degrade hazardous pollutants and act as an antimicrobial. It employs visible light to solve environmental issues positively.

Green synthesis of silver nanoparticles from supercritical CO2 mediated Lagerstroemia speciosa extract: Characterization, antimicrobial and antibiofilm activity

In the current study, optimal supercritical fluid extract (SFE) of Lagerstroemia speciosa (LS) leaves at pressure 29.59 megapascal (MPa), temperature 89.50 ºC and extraction time 53.85 min. was used to extract phenolic compounds for the synthesis of silver nanoparticles (AgNPs). The synthesis was studied for 0-20 hrs. Initially the synthesis of nanoparticles (SFELS-AgNPs) was confirmed using UV -spectroscopy. It demonstrated a maximum surface plasmon resonance at 430 nm. The crystallite dimension of nanoparticles was determined using X-ray diffraction (XRD) (13.47 nm), Transmission electron microscopy (TEM), zeta potential analysis and energy-dispersive X-ray analysis (EDAX) were used to analyze the morphology, surface charge and presence of differential elements in SFELS-AgNPs respectively. Developed nanoparticles revealed antimicrobial activity against two gram-positive viz. Staphylococcus aureus and Bacillus cereus, and three gram-negative bacteria viz. Klebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli. The nanoparticle showed a minimum inhibitory concentration (MIC) of 64 μg/ml whereas the minimum bactericidal concentration (MBC) 128 μg/ml against K. pneumonia. They significantly inhibited K. pneumonia biofilm formation which was confirmed using scanning electron microscopy (SEM). The results were encouraging compared to the standards drug Chloramphenicol and other controls. The generated nanoparticles have highly effective antimicrobial properties against pathogenic bacteria.

Colistin-niclosamide effervescent dry suspension combats colistin-resistant Salmonella in vitro and in vivo

The increasing incidence of bacterial infections caused by multidrug-resistant (MDR) Gram-negative bacteria has deepened the need for new effective treatments. It has been reported that niclosamide (NIC) can restore the sensitivity of Gram-negative bacteria to colistin (COL). However, NIC is practically insoluble in water and sparingly soluble in organic solvents, leading to limited therapeutic applications. This study aims to prepare a COL-NIC effervescent dry suspension (CNEDS) and evaluate its antibacterial effect against COL-resistant Salmonella both in vitro and in broiler chickens. With the sedimentation volume ratio as an index, suitable suspending agent, wetting agent, filler and effervescent agent were screened through a single-factor method. The preparation conditions were optimized using the Box-Behnken response surface method to obtain the formulation for CNEDS. The quality evaluation results showed that the successfully prepared CNEDS had a sedimentation volume ratio of 0.99, a drying weight loss of 1.3%, and a re-dispersion capability of 1-2 times, all of which met pharmacopoeial requirements. In terms of pharmacological evaluation, we first demonstrated that CNEDS substantially restored COL sensitivity against COL-resistant bacteria. Subsequently, time-killing analysis, scanning electron microscopy (SEM) and live/dead assays confirmed the antibacterial activity of CNEDS against COL-resistant bacteria. Finally, a Salmonella infection model in broiler chickens was established to further assess the therapeutic effect of CNEDS in vivo. CNEDS improved the survival rate of broiler chickens, reduced the bacterial burden on organs. These findings suggest that CNEDS effectively overcome COL resistance, indicating its potential for the treatment of COL-resistant bacterial infections in broiler chickens.

MAM7 from Vibrio parahaemolyticus: Expression, purification and effects on RAW264.7cells.

V. parahaemolyticus is a Gram-negative bacterium that causes gastroenteritis. Within the realm of bacterial interactions with the gut, the outer membrane protein MAM7 plays a key role. However, the precise function of MAM7 in intestinal inflammation, particularly its interactions with macrophages, remains unclear. In this study, we successfully expressed and purified recombinant MAM7. After optimization of the MAM7 expression condition, it was found that the optimal concentration and temperature were 0.75mM and 15°C, respectively, resulting in a 27-fold increase in its yield. Furthermore, RAW264.7 cytotoxicity assay was conducted. The CCK-8 results revealed that MAM7 substantially stimulated the proliferation of RAW264.7cells, with its optimal concentration determined to be 7.5μg/mL. Following this, the NO concentration of MAM7 was tested, revealing a significant increase (p<0.05) in NO levels. Additionally, the relative mRNA levels of IL-1β, IL-6, and TNF-α in RAW264.7cells were measured by qRT-PCR, showing a remarkable elevation (p<0.05). Moreover, ELISA results demonstrated that MAM7 effectively stimulated the secretion of IL-6 and TNF-α by RAW264.7cells. In summary, these findings strongly suggest that MAM7 serves as a proinflammatory adhesion factor with the capacity to modulate immune responses.

Investigations on Photodegradation and Antibacterial Activity of Mixed Oxide Nanocrystalline Materials

In this study, we synthesized cobalt-doped molybdenum supported on silica (Co/MS) nanocomposites with varying concentrations of cobalt (1, 5, 10, 15, and 20 wt%) using the sol-gel method. We investigated their physico-chemical properties, photocatalytic activity, and antimicrobial efficacy. The synthesized nanocomposites were characterized using a range of techniques, including X-ray powder diffraction (XRD) to determine crystal structure, UV-vis spectroscopy for optical properties, Fourier transform infrared spectroscopy (FT-IR) for functional group analysis, and scanning electron microscopy coupled with energy-dispersive X-ray microanalysis (SEM-EDX) for morphological and elemental composition analysis. The photocatalytic performance of these catalysts was assessed by their ability to degrade organic dyes, specifically methyl orange and methylene blue, under visible light irradiation. Our results demonstrated that the photocatalytic efficiency increased with higher cobalt content, with the 20 wt% Co/MS nanocomposite showing the highest degradation rates. Additionally, we evaluated the antibacterial activity of the nanocomposites against a range of microorganisms, including Gram-positive and Gram-negative bacteria, as well as fungal species. The 20 wt% Co/MS nanocomposite exhibited superior antimicrobial activity compared to the other samples, indicating its potential for applications in environmental remediation and antimicrobial treatments.

Neonatal sepsis – etiological study at the Central Park teaching Hospital, Lahore.

Objective: To identify the causative bacteria responsible for early and late onset neonatal sepsis and to determine their antibiotic susceptibilities at Central Park Teaching Hospital. Study Design: Cross-sectional study. Setting: Neonatal Intensive Care Unit (NICU) of Central Park Teaching Hospital, Lahore. Study Period: Jan to June 2024. Methods: Neonates up to 28 days old with clinical features of sepsis were randomly sampled and included in the study. Key maternal and neonatal risk factors were evaluated. Blood cultures were analyzed to identify microbial isolates and assess resistance patterns. Demographic data, clinical features, and blood culture results were collected and analyzed using SPSS version 26.0. Results: Out of the cases studied, 55% were male. Early onset sepsis was slightly more prevalent at 51.5%. Significant maternal risk factors for early sepsis included maternal fever, offensive liquor, and prolonged second stage of labor. Blood cultures were positive in 18.8% of cases, with early onset sepsis accounting for 44.7% of positives and late onset sepsis for 55.3%. Gram-positive bacteria were more common in early sepsis (48.1%), with Acinetobacter baumannii and Candida blankii being notable isolates, while Gram-negative bacteria were more prevalent in late sepsis (63.6%), with Bacillus spp. and Burkholderia cenoc as key pathogens. Coagulase-negative Staphylococcus was the most frequently isolated pathogen in both early and late sepsis. Conclusion: The study underscores the importance of developing tailored antimicrobial strategies based on the timing of sepsis onset to improve neonatal outcomes. Significant differences in microbial distribution between early and late neonatal sepsis were observed (p &lt; 0.001).

Caught Between Stewardship and Resistance: How to Treat Acute Complicated Diverticulitis in Areas of Low Antimicrobial Susceptibility?

Antimicrobial resistance is one of the main threats to public health, with multidrug-resistant (MDR) pathogens on the rise across continents. Although treatment guidelines generally recommend antimicrobial therapy for acute complicated diverticulitis, they do not specify treatment pathways according to local or national resistance profiles. There is sparse data regarding specific pathogens involved in Hinchey II–IV patients who undergo surgery. This study seeks to address these issues and determine how often and what types of MDR bacteria occur in patients undergoing emergency surgery. We prospectively enrolled patients admitted between 2020–2023 and who underwent emergency surgery for complicated acute diverticulitis. We analysed the inflammatory response parameters at admission, the type of surgery employed for source control, identified pathogens in the peritoneal samples, their antimicrobial susceptibility, the efficacy of antimicrobial empiric therapy, and mortality. Gram-negative bacteria were identified most often, with Escherichia coli being mostly MDR (43.9%) or extended-spectrum beta-lactamase producing (ESBL +ve) (24.4%), while most strains of Klebsiella pneumoniae were extended-spectrum beta-lactamase positive (ESBL +ve) (80%) and MDR (80%). Of the Enterococcus spp., 57.14% were vancomycin-resistant (VRE) strains. Patients with Hinchey III/IV were significantly more associated with MDR. Patients with multiple pathogens were significantly associated with ESBL+/VRE strains. Age, leucocytosis, and procalcitonin levels at admission were good indicators for mortality prediction, which occurred in four cases. In an age when antibiotic stewardship is advisable especially in emergency settings, the treatment should be tailored according to local profiles of MDR to ensure adequate outcomes for patients.

National Cohort of Compassionate Use of Meropenem–Vaborbactam: No Benefit over Meropenem for Pseudomonas aeruginosa

Background: Meropenem–vaborbactam (MEM-VAB) is a novel carbapenem-beta-lactamase-inhibitor combination that demonstrates activity against carbapenem-resistant (CR) Gram-negative bacteria, and more specifically KPC-producers, since vaborbactam is an effective inhibitor of KPC enzymes in vitro. This study aimed to describe the initial uses and efficacy of MEM-VAB for compassionate treatment during the first 21 months following its early access in France. Method: A national multicenter retrospective study was conducted, including all patients who received at least one dose of MEM-VAB between 20 July 2020, and 5 April 2022. Clinical characteristics and outcomes were collected using a standardized questionnaire. The minimum inhibitory concentration (MIC) of antimicrobials, and complete genome sequencing of bacteria were performed when bacterial isolates were available. Results: Ultimately, 21 patients from 15 French hospitals were included in the study. The main indication for MEM-VAB treatment was respiratory tract infections (n = 9). The targeted bacteria included Pseudomonas aeruginosa (n = 12), Klebsiella pneumoniae (n = 3), Enterobacter spp (n = 3), Citrobacter freundii (n = 1), Escherichia coli (n = 1), and Burkholderia multivorans (n = 1). Overall, no significant advantage of vaborbactam over meropenem alone was observed across all strains of P. aeruginosa in terms of in vitro susceptibility. However, MEM-VAB demonstrated a notable impact, compared to carbapenem alone, on the MIC for the two KPC-3-producing K. pneumoniae and B. multivorans. Conclusions: MEM-VAB seems effective as a salvage treatment in compassionate use, but vaborbactam was shown to lack benefits compared to meropenem in treating P. aeruginosa-related infections. Therefore, it is crucial to compare meropenem to MEM-VAB MICs, particularly for P. aeruginosa, before prescribing MEM-VAB.

Synthesis of Antimicrobial and Antioxidant Zinc Oxide Hydrogel for Drug Delivery Applications

A novel and simple method was used to synthesize antimicrobial and antioxidant porous (N-tert-butylacrylamide-co-N-vinylpyrrolidone) zinc oxide hydrogel via free radical copolymerization. The hydrogel was characterized by NMR, XRD, and SEM. Thermodynamic properties of the hydrogel were described quantitatively by the Flory-Rehner method. The results indicate that the synthesized hydrogel exhibits strong antioxidant activity, making it a potential candidate for use in preventing degenerative diseases. The antimicrobial tests showed that the hydrogel could inhibit the growth of Gram-positive and Gram-negative bacteria, as well as some pathogenic bacteria and fungi. The inhibition zones ranged from 10 to 15 mm for bacteria and from 5.2 to 9.1 mm for fungi. The reactivity ratio r1 × r2 equal to 1 confirmed ideal copolymerization showed the composition of the copolymer and the comonomer feed are same. The hydrogel's structure and reactivity are significant for constructing effective delivery systems for specific applications. Optimizing the monomer proportion could enhance hydrogel efficiency and release behavior. The hydrogel's water solubility, non-toxicity, and antioxidant properties suggest it could be safe and effective throughout the drug delivery process, contributing both passive and reactive targeting functions.

2-Aminobenzothiazole based adjuvant of polymyxin E against Gram-negative bacteria

Antibiotic resistance has emerged as a pressing global health issue. Polymyxin E, commonly regarded as a clinically important antibiotic, faces limitations due to its dose-dependent toxicity. A crucial strategy to combat this is the development of an antibiotic adjuvant to enhance efficacy while reducing dosage. Screening from our extensive in-house compound library, KJ1071 emerged as a promising adjuvant candidate for polymyxin E. Subsequent structure–activity relationship studies led to the discovery of compound A35, which demonstrated superior synergistic activity. However, its limited aqueous solubility posed challenges for biological experiments. To address this, we carried out a structural derivatization aimed at enhancing its solubility. The amino acid derivative A59 notably improved aqueous solubility to 3.237 mg/mL, a substantial 3237-fold increase compared to compound A35. Moreover, A59 amplified the efficacy of polymyxin E in eradicating a variety of Gram-negative bacteria, including certain clinical strains that are resistant to polymyxin E. The mechanism studies indicated that A59 might target the bacterial membrane. These findings suggest that the discovery of this innovative scaffold could provide critical insights for new adjuvant therapies.

Synthesis, Characterization, Biological, and Antioxidant Activity of New Metal Ion Complexes with Schiff Base Derived from 2-Hydroxybenzohydrazide

The study involved the synthesis of new complexes with tetradentate ligand (LH). The general formula of complexes was [M(LH)(H2O)2] with M of Ni2+, Co2+, Cu2+, and Zn+. The ligand was synthesized by treating the 2-hydroxybenzohydrazide with salicylaldehyde. The structural characteristics of ligands and complexes were analyzed using various techniques, including elemental analyses, magnetic susceptibility, molar conductivity, infrared, ultraviolet absorption, mass, and NMR spectroscopy studies. The physical measurements indicated that the prepared complexes are non-electrolyte and showed that the ligand is tetradentate when coordinated with metal ions through the nitrogen of azomethine (–C=N–), two oxygen atoms of O–H phenolic, and an oxygen atom of carbonyl (C=O) for benzohydrazide. It was found that Co2+, Cu2+, and Zn2+ complexes are octahedral, while Ni2+ complexes are square planar. The biological screening of the complexes demonstrates that the Schiff base metal complexes exhibit remarkable efficacy in combating microorganisms by utilizing Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) bacteria, as well as Candida albicans fungi. Hence, their results were good in inhibition. Then, the potential of these prepared compounds as antioxidants was determined by inhibiting free radicals.

Carboxymethylcellulose-based aggregation-induced emission antibacterial material for multifunctional applications.

Polysaccharides are ubiquitous in nature, typically harmless, and highly compatible with various tissues in biomedical contexts. These properties make them attractive for use in multifunctional materials. In this study, the aggregation-induced emission (AIE) antibacterial material (PLOCMC) was successfully synthesized by carboxymethylcellulose (CMC) and ε-Poly-Lysine (ε-PL). PLOCMC exhibits not only the AIE property but also a room temperature phosphorescent (RTP) phenomenon. This dual emission behavior enhances its potential applications in chemical sensing and anti-counterfeiting. Notably, PLOCMC shows low cytotoxicity and exhibits antibacterial activity against typical Gram-positive and Gram-negative bacteria, making it a potent agent against a variety of bacterial strains. Additionally, PLOCMC demonstrates specific responsiveness to Fe3+ ions and nitrite, indicating its potential utility in food safety and monitoring applications.

Antibacterial Activity of Reduced Graphene-Silver Oxide Nanocomposite against Gram-Negative Bacteria

Antibacterial Activity of Reduced Graphene-Silver Oxide Nanocomposite against Gram-Negative Bacteria

Synergistic interaction of green-synthesized titanium dioxide nanoparticles and Averrhoa carambola extract in chitosan films.

Chitosan-based films incorporated with green-synthesized TiO2 nanoparticles (CT) and Averrhoa carambola extract (CP) at different concentrations were fabricated and optimised based on enhanced tensile, moisture-gas barrier and retention capabilities of antioxidants. Chitosan incorporated with 0.06 % TiO2 NP and those incorporated with 6 % carambola extract exhibited optimal results, and developed films of the above two concentrations of the additives were blended into chitosan (CTP) for further analysis. Biodegradability assays confirmed the ecological sustainability of the films. FT-IR revealed a successful interaction between the additives and the chitosan. The XRD spectra of the control film and film containing carambola extract and TiO2 NP reveal a broad, amorphous nature, with carambola extract altering diffraction peaks. SEM revealed homogenous surfaces in control films, whereas those incorporated with the additives showed granules and microstructures. TGA revealed that the heat stability of chitosan-based films infused with TiO2 NP was boosted compared to those infused with carambola extract. Antimicrobial profiling showed good inhibition against gram-positive bacteria (E. faecalis and S. aureus), gram-negative bacteria (P. aeruginosa and E. coli), and a fungus (C. tropicalis). The developed biodegradable films are potential natural alternative food packaging or edible coating for delaying the maturation of fresh harvests.

Analysis of risk factor microflora colonization on pregnancy vagina in makassar

Introduction: Worldwide infection rates based on estimated 20-30 % colonization at 35 weeks gestation. During normal pregnancy colonization transient, intermittent, or chronic infection and the spectrum varies from asymptomatic colonization to the sepsis. Intrapartum transmission of bacteria from mother to neonatal, will cause the infection develops into neonatal sepsis during childbirth. This study aimed to determine the proportion of the colonization of gram positive and negative bacteria in pregnant women over 31 weeks of age. Research Methodology: This research uses vaginal swab samples from pregnant women and blood samples from babies who are born, then these samples will be examined in the Unhas Hospital laboratory. Vaginal swab samples via transport medium will be placed in BHIB medium then incubated at 270 C for 24 hours. Result: Prevalence of gram-positive bacterium identified Streptococcus species (0.9%), S. Aureus (11.8%) and S. Epidermidis (78.4%). For gram-negative bacteria had identified; Enterobacter Sp (32.3%), Providencia Sp (12.7%), Proteus Sp (8.8%), Acinetobacter sp (5.9%) and E. Coli (6.9%). Candida Sp obtained on SDA culture and gram staining followed by a number of 54 samples (55.1%). The symptom was to be is Discharge Vagina over 30% cases. Among 76.6% with habitually antiseptic usual. Based on data statistical analysis can be concluded that the age have a significance level 0:01 (ρ &lt; 0.05) .and contraceptive used have a significance level of 0.038 (ρ &lt; 0.05), had a relationship with a potential fetomaternal infection to infant. Conclusion: that maternal age and history of contraceptive use are significantly associated with bacterial colonization in pregnant women. These findings underscore the need to consider demographic and behavioral factors when assessing and managing vaginal health during pregnancy. Effective educational interventions focusing on proper hygiene practices and the risks associated with antiseptic soap use, coupled with targeted monitoring of older pregnant women and those with a history of contraceptive use, are recommended to reduce the risks associated with vaginal microbial colonization

Zn-MIL53(Fe) as an electro-Fenton catalyst: Application in organic pollutant degradation and pathogen inactivation

In this study, the potential of a bimetallic Metal-Organic Framework Zn-MIL53(Fe) for electro-Fenton catalysis was evaluated. After the material characterisation, its catalytic activity was validated in Fenton reaction to degrade a model organic pollutant: Rhodamine B. After that, the evaluation of Zn-MIL53(Fe) as electro-Fenton catalyst was performed and improved outcomes were reached by electro-Fenton regarding anodic oxidation. Then, electro-Fenton treatment optimisation was carried out using response surface methodology assays considering different catalyst dosages (7.2–43.2 mg), current intensities (5–45 mA) and treatment time (30–90 min) in a volume of 0.1 L. Under optimal conditions, a degradation rate over 90 % for Fluoxetine and Sulfamethoxazole in synthetic wastewater was achieved within 90 min, using graphite sheet as anode and nickel foam as cathode (25 mA), with a catalyst dosage of 43.2 mg in a volume of 0.1 L. Additionally, its application in the pathogen inactivation was evaluated using different gram-negative and gram-positive bacteria. Complete eliminations of both types of bacteria were reached in 5 min using the optimal conditions. In the end, Zn-MIL53(Fe) was proven as a reusable material, capable of performing 3 complete cycles of electro-Fenton treatment for both types of pollutants bacteria and pharmaceuticals, which makes it a promising candidate for more efficient wastewater treatment applications which involve the Fenton reaction.

Folic acid functionalized Ag@MOF(Ag) decorated carboxymethyl starch nanoparticles as a new doxorubicin delivery system with inherent antibacterial activity

Considering the benefits of controlled drug delivery in cancer treatment, as well as the importance of biological macromolecules in this area, herein, the pre-synthesized carboxymethyl starch (CMS) was converted to CMS nanoparticles (CMS NPs) in one easy nanoprecipitation way. Thereafter, the Ag@MOF(Ag) was in situ synthesized in the presence of pre-prepared CMS NPs (CMS NPs/Ag@MOF(Ag)). Eventually, the functionalization with folic acid (FA) obtained the CMS NPs/Ag@MOF(Ag)-FA. The success of the accomplished process was approved by doing several techniques, including FT-IR, XRD, EDX, AFM, etc. The SEM analysis showed a combination of rod-like and spherical-like morphology for the fabricated bio-nanocomposite. The generated CMS NPs/Ag@MOF(Ag)-FA with a surface area of 10.595 m2/g displayed a pore size of 13.666 nm and 82.99 % of doxorubicin (DOX) loading efficiency (DOX@CMS NPs/Ag@MOF(Ag)-FA). The 38.46 % and 58.19 % of loaded DOX were released respectively within 240 h at pH 7.4 and pH 5.0, referring to the pH-responsivity of the constructed system. 27.25 % of inhibitory effects on HeLa cells were obtained for the drug-loaded bio-nanocomposite. The CMS NPs/Ag@MOF(Ag)-FA also displayed an inherent antibacterial activity towards two common gram-negative and gram-positive bacteria. All of these results can contribute to developing polysaccharide-based porous systems in controlled cancer therapy.

Preparation and properties of calcium oxide and calcium peroxide from eggshell waste for enhanced antimicrobial activity

Calcium peroxide (CaO2), which releases hydrogen peroxide (H2O2) upon contact with water, has garnered attention as a potential alternative to liquid H2O2. Researchers have explored various methods to enhance the production of CaO2 with reduced environmental impact. This study focuses on the preparation of two potent antimicrobial agents, calcined calcium oxide (C-CaO) and synthesized calcium peroxide (S-CaO2) from eggshell waste. These agents were then incorporated into ethylene vinyl alcohol (EVOH) composite films for antimicrobial packaging. The synthesized CaO and CaO2 were analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM). The results confirmed the successful synthesis of high-purity CaO and CaO2 from eggshell waste. Compared to CaO (a well-known antimicrobial agent), CaO2 exhibited approximately 1.6 to 2 times higher antimicrobial activity, which is attributed to its release of H2O2. EVOH films containing 3% of CaO2 demonstrated significant microbial growth deactivation, reaching 99.99% and 97.24% for gram-negative and gram-positive bacteria, while EVOH films containing 3% of CaO exhibited relatively low deactivation ability of 79.01% and 48.82, respectively. This study underscores the potential of eggshell waste as a valuable resource for producing high-value materials. Moreover, CaO2 emerges as an effective antimicrobial agent, particularly in antimicrobial packaging applications, showcasing its versatility across various sectors.

Cu2O@Cu-composed hollow spheres capable of Generating Rich reactive oxygen species for efficient photodynamic antibacterial application

Cuprous oxide (Cu2O), which has an appropriate band gap, is widely used as a marine antifouling biocide. This makes it increasingly valuable for photocatalytic antibacterial applications. Using crystal engineering technology to create Cu2O with tailored Cu2O/Cu interfaces and crystal planes can effectively enhance its performance but presents challenges. Herein, we report a simple wet chemical method for the controlled preparation of Cu2O@Cu hollow heterostructure. Experimental results demonstrate that the prepared composites exhibited highly efficient and broad-spectrum photocatalytic antibacterial effects against both Gram-negative and Gram-positive bacteria, achieving 100% antibacterial efficiency under 10 min of irradiation, much more effective than the bulk Cu2O. Characterization results show that a hollow spherical structure consisted of fine Cu2O@Cu nanoparticles in their wall, and the generated interfaces facilitated the migration and separation of photogenerated charge carriers and promoted the formation of hydroxyl radicals with stronger oxidizing abilities. Meanwhile, the Cu outside layer of each Cu2O@Cu particle not only acted as a shield to protect Cu2O from corrosion but also served as an electron acceptor to efficiently transfer photogenerated electrons, thereby demonstrating highly effective and stable antibacterial performance. This study not only offers a valuable reference for developing highly efficient and universal photocatalytic materials but also provides insight into the chemical reaction in the photocatalytic antibacterial process.

Repurposing of monocyclic β-lactams as anti-inflammatory agents – The case of new ferrocene-azetidin-2-one hybrids

There is growing interest in developing monotherapy drugs that treat inflammation caused by microbial infections, focusing on dual antimicrobial and anti-inflammatory agents with minimal side effects and high safety margins. This study synthesized and characterized a library of novel cis-4-ferrocenylazetidin-2-ones, evaluating their antimicrobial and anti-inflammatory activities. These organometallic monocyclic β-lactams showed moderate in vitro antimicrobial activity against various standard microbial strains, including yeasts and Gram-negative and Gram-positive bacteria. Some compounds overcame the resistance of clinical Staphylococcus aureus isolates. Traditionally, monocyclic β-lactams target Gram-negative bacilli, but adding a ferrocene moiety and substituting the COOH group near the N-1 position with a non-ionizable ester group (COOR) extended their activity spectrum. The anti-inflammatory properties were assessed in macrophage-based models, revealing non-cytotoxicity below 10 μM. Two compounds were shown to be strong and selective arginase inhibitors, while five others effectively suppressed excessive NO formation without affecting basal NO production. The presence of a phenoxy group at C-3 of the β-lactam ring appeared to be crucial for selective NO inhibition. These hybrids did not scavenge NO but inhibited NO synthesis by suppressing iNOS expression. Overall, two novel hybrids were identified as promising hit candidates for treating infection-induced inflammatory reactions.