Imaging of intracellular behavior of polymeric nanoparticles in Staphylococcus epidermidis biofilms by slit-scanning confocal Raman microscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy

Green synthesis of zinc oxide nanoparticles from Sida acuta leaf extract for antibacterial and antioxidant applications, and catalytic degradation of dye through the use of convolutional neural network

This study synthesized zinc oxide nanoparticles (ZnO NPs) using a novel green approach, with Sida acuta leaf extract as a capping and reducing agent to initiate nucleation and structure formation. The innovation of this study lies in demonstrating the originality of utilizing zinc oxide nanoparticles for antibacterial action, antioxidant potential, and catalytic degradation of Congo red dye. This unique approach harnesses eco-friendly methods to initiate nucleation and structure formation. The synthesized nanoparticles' structure and conformation were characterized using UV-vis (λmax = 280 nm), X-ray, atomic force microscopy, SEM, HR-TEM and FTIR. The antibacterial activity of the Nps was tested against Pseudomonas sp, Klebsiella sp, Staphylococcus aureus, and E. coli, demonstrating efficacy. The nanoparticles exhibited unique properties, with a crystallite size of 20 nm (XRD), a surface roughness of 2.5 nm (AFM), and a specific surface area of 60 m2/g (SEM). A Convolutional Neural Network (CNN) was effectively employed to accurately classify and analyze microscopic images of green-synthesized zinc oxide nanoparticles. This research revealed their exceptional antioxidant potential, with an average DPPH scavenging rate of 80% at a concentration of 0.05 mg/mL. Additionally, zeta potential measurements indicated a stable net negative surface charge of approximately -12.2 mV. These quantitative findings highlight the promising applications of green-synthesized ZnO NPs in healthcare, materials science, and environmental remediation. The ZnO nanoparticles exhibited catalytic capabilities for dye degradation, and the degradation rate was determined using UV spectroscopy. Key findings of the study encompass the green synthesis of versatile zinc oxide nanoparticles, demonstrating potent antibacterial action, antioxidant capabilities, and catalytic dye degradation potential. These nanoparticles offer multifaceted solutions with minimal environmental impact, addressing challenges in various fields, from healthcare to environmental remediation.

Fate of Biodegradable Engineered Nanoparticles Used in Veterinary Medicine as Delivery Systems from a One Health Perspective

The field of veterinary medicine needs new solutions to address the current challenges of antibiotic resistance and the need for increased animal production. In response, a multitude of delivery systems have been developed in the last 20 years in the form of engineered nanoparticles (ENPs), a subclass of which are polymeric, biodegradable ENPs, that are biocompatible and biodegradable (pbENPs). These platforms have been developed to deliver cargo, such as antibiotics, vaccines, and hormones, and in general, have been shown to be beneficial in many regards, particularly when comparing the efficacy of the delivered drugs to that of the conventional drug applications. However, the fate of pbENPs developed for veterinary applications is poorly understood. pbENPs undergo biotransformation as they are transferred from one ecosystem to another, and these transformations greatly affect their impact on health and the environment. This review addresses nanoparticle fate and impact on animals, the environment, and humans from a One Health perspective.

Optical nanosensors for biofilm detection in the food industry: principles, applications and challenges

Biofilms are the universal lifestyle of bacteria enclosed in extracellular polymeric substances (EPS) on the contact surfaces of food processing facilities. The EPS-encapsulated foodborne bacterial pathogens are the main food contaminant sources, posing a serious threat to human health. The microcrystalline, sophisticated and dynamic biofilms necessitate the development of conventional microscopic imaging and spectral technology. Nanosensors, which can transfer the biochemical information into optical signals, have recently emerged for biofilm optical detection with high sensitivity and high spatial resolution at nanoscale scopes. Therefore, the aim of this review is to clarify the main detection scope in biofilms and the detection principles of optical nanosensors arousing Raman enhancement, fluoresce conversion and color change. The difficulties and challenges of biofilm characterization including the secretion and variation of main biochemical components are first discussed, the details about the principles and application examples of bioassays targeting foodborne pathogens based on optical nanosensors are then summarized. Finally, the challenges and future trends in developing optical nanosensors are also highlighted. The current review indicates that optical nanosensors have taken the challenges of detecting biofilm in complex food samples, including the characterization of biofilm formation mechanism, identification of microbial metabolic activities, diagnosis of potential food pathogens and sanitation monitoring of food processing equipment. Numerous in-depth explorations and various trials have proven that the bioassays based on multifunctional optical nanosensors are promising to ensure and promote food safety and quality. However, there still remains a daunting challenge to structure reproducible, biocompatible and applicable nano-sensors for biofilm characterization, identification, and imaging.

Environmental conditions shape the biofilm of the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

Biofilms are the most widely distributed and successful microbial modes of life. The capacity of bacteria to colonize surfaces provides stability in the growth environment, allows the capturing of nutrients and affords protection from a range of environmental challenges and stress. Bacteria living in cold environments, like Antarctica, can be found as biofilms, even though the mechanisms of how this lifestyle is related to their environmental adaptation have been poorly investigated. In this paper, the biofilm of Pseudoalteromonas haloplanktis TAC125, one of the model organisms of cold-adapted bacteria, has been characterized in terms of biofilm typology and matrix composition. The characterization was performed on biofilms produced by the bacterium in response to different nutrient abundance and temperatures; in particular, this is the first report describing the structure of a biofilm formed at 0 °C. The results reported demonstrate that PhTAC125 produces biofilms in different amount and endowed with different physico-chemical properties, like hydrophobicity and roughness, by modulating the relative amount of the different macromolecules present in the biofilm matrix. The capability of PhTAC125 to adopt different biofilm structures in response to environment changes appears to be an interesting adaptation strategy and gives the first hints about the biofilm formation in cold environments.

Modulation of quantum dots and clearance of Helicobacter pylori with synergy of cell autophagy

Helicobacter pylori (Hp) is one type of Gram-negative pathogenic bacterium that colonizes and causes a wide range of gastric diseases. Once Hp penetrates into cells, the currently recognized triple or quadruple therapy often loses effectiveness. Recent evidence suggests that autophagy is closely associated with Hp infection, and can play an important role in the eradication of Hp. More importantly, certain types of quantum dots (QDs) can induce and modulate cellular autophagy, and can be developed into conjugates making QDs potential candidates as new anti-Hp agents.