Bacterial drug resistance poses a global challenge to established antibacterial prevention and treatment schemes. Recent approaches focus on raising algal extracts' efficacy by fusing them to other antibacterial agents employing nanotechnology. Here, we successfully biosynthesized AgNPs using Galaxaura rugosa crude methanol extract (AgNP_CR) and raw powder aqueous (AgNP_AQ) solution. The resultant AgNPs were characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy. The AgNPs were spherical and ranged between 60 to 114.4 nm. The presence of the hydroxyl group and alkenes propped AgNPs biosynthesis. We investigated AgNPs antibacterial and antibiofilm activity against eighteen medically important bacteria, including multidrug-resistant bacteria. The sensitive and resistant Acinetobacter baumannii and Staphylococcus aureus were the most affected strains. The biofilm of MDR strains was mostly disturbed, indicating the reduced bacterial fitness in resistant strains. These results may aid antibacterial agents' development by investing in natural resources available abundantly in our environment.

The adaptive nature of algae results in producing unique chemical components that are gaining attention due to their efficiency in many fields and abundance. In this study, we screened the phytochemicals from the brown alga Hydroclathrus clathratus and tested its ability to produce silver nanoparticles (AgNPs) extracellularly for the first time. Lastly, we investigated its biological activity against a variety of bacteria. The biosynthesized nanoparticles were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and energy-dispersive spectroscopy. The biological efficacy of AgNPs was tested against eighteen different bacteria, including seven multidrug-resistant bacteria. Phytochemical screening of the alga revealed the presence of saturated and unsaturated fatty acids, sugars, carboxylic acid derivatives, triterpenoids, steroids, and other components. Formed AgNPs were stable and ranged in size between 7 and 83 nm and presented a variety of shapes. Acinetobacter baumannii , Staphylococcus aureus , Methicillin-resistant S. aureus (MRSA), and MDR A. baumannii were the most affected among the bacteria. The biofilm formation and development assay presented a noteworthy activity against MRSA, with an inhibition percentage of 99%. Acknowledging the future of nano-antibiotics encourages scientists to explore and enhance their potency, notably if they were obtained using green, rapid, and efficient methods.

Background and Purpose. Gentamicin (GEN) is a broad-spectrum antibiotic that cannot be prescribed freely because of its toxicity. Thymoquinone (THQ), a phytochemical, has antibacterial, antioxidant, and toxicity-reducing properties. However, its hydrophobicity and light sensitivity make it challenging to utilize. This incited the idea of co-encapsulating GEN and THQ in liposomes (Lipo-GEN-THQ). Method. Lipo-GEN-THQ were characterized using the zeta-potential, dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscope (TEM). The liposomes’ stability was evaluated under different storage and biological conditions. Lipo-GEN-THQ’s efficacy was investigated by the minimum inhibitory/bactericidal concentrations (MICs-MBCs), time–kill curves, and antibiofilm and antiadhesion assays. Bacterial interactions with the empty and GEN-THQ-loaded liposomes were evaluated using TEM. Results. The Lipo-GEN-THQ were spherical, monodispersed, and negatively charged. The Lipo-GEN-THQ were relatively stable and released GEN sustainably over 24 h. The liposomes exhibited significantly higher antibacterial activity than free GEN, as evidenced by the four-fold lower MIC and biofilm eradication in resistant E. coli strain (EC-219). TEM images display how the empty liposomes fused closely to the tested bacteria and how the loaded liposomes caused ultrastructure damage and intracellular component release. An antiadhesion assay showed that the Lipo-GEN-THQ and free GEN (0.125 mg/L) similarly inhibited Escherichia coli (EC-157) adhesion to the A549 cells (68% vs. 64%). Conclusions. The Lipo-THQ-GEN enhanced GEN by combining it with THQ within the liposomes, reducing the effective dose. The reduction in the GEN dose after adding THQ may indirectly reduce the toxicity and aid in developing an enhanced and safer form of GEN.

Background: The emergence of multidrug-resistant bacteria presents a significant global health threat. Liposomal antibiotics have shown a potential to improve antibiotic delivery and efficacy. This study aimed to develop liposomes encapsulating tobramycin (TOB) and methylglyoxal (MGO) to enhance TOB activity while reducing bacterial adhesion and biofilm formation. Methods: Clinical isolates of Pseudomonas aeruginosa and Klebsiella pneumoniae were characterized using whole-genome sequencing. Liposomes (Lip-MGO-TOB) were formulated using Manuka honey as a surfactant and loaded with MGO and TOB. Antibacterial activity, biofilm formation, and bacterial cell adhesion assays were performed to compare the efficacy of Lip-MGO-TOB against free TOB. Liposome characterization included analyses of morphology, zeta potential, TOB encapsulation efficiency, and stability under various biological conditions. Results: The Lip-MGO-TOB formulation, at a minimum inhibitory concentration (MIC) of 32 µg/mL, reduced the biofilm formation of the P. aeruginosa isolate (PA85) by 68%. Conversely, free TOB, at a MIC of 64 µg/mL, achieved only a 21% reduction. For the K. pneumoniae isolate (KP57), Lip-MGO-TOB inhibited bacterial adhesion to A549 cells at a lower concentration (256 µg/mL) compared to free TOB (512 µg/mL). Lip-MGO-TOB demonstrated sustained drug release over 24 h under tested conditions and retained over 99% of TOB. Conclusions: The Lip-MGO-TOB formulation significantly enhanced TOB activity against resistant bacteria compared to free TOB. Additionally, it provided a stable drug delivery system with controlled drug release. Liposomal TOB represents a promising advancement in combating antibiotic resistance by improving the efficacy and delivery of conventional antibiotics.

Background/Objectives: Ciprofloxacin (CIP) is a fluoroquinolone extensively used in hospital settings and for the treatment of bacterial infections; however, this antibiotic requires multiple doses because it has poor absorption, rapid elimination, and is ineffective against resistant bacterial strains. Enhanced delivery efficiency could also be used in the dose-sparing techniques, resulting in better antibiotic efficacy. The aim of this study was to improve CIP-loaded chitosan nanoparticles (NPs) and to evaluate their capacity to enhance the antibacterial response in sensitive and resistant bacterial isolates. Methods: CIP-loaded chitosan nanoparticles were fabricated via ionic gelation using sodium tripolyphosphate (TPP) as a crosslinking agent. Formulation parameters, such as CIP concentration and polymer-to-crosslinker ratios, were optimized. The obtained nanoparticles were evaluated for particle size, polydispersity index, zeta potential, entrapment efficiency, morphology, stability, and in vitro release studies. Antibacterial efficacy was evaluated by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against standard and ciprofloxacin-resistant clinical isolates. Results: Successful optimization of these formulations allowed the preparation of stable nanoparticles that ranged from 38.39 to 115.07 nm, highlighting the role of both the formulation composition and polymer-to-crosslinker ratios on the size of the nanoparticles. The formulation exhibits a drug entrapment efficiency of 84.1% and uniform particulate size (38.39 ± 0.63 nm), which were optimized due to the polymer and crosslinker ratios. These nanoparticles showed a slow release of the drug over 220 hours, and minimal size instability was noted after 28 days. Encapsulation of CIP resulted in enhanced antibacterial activity, yielding 2-4-fold reductions in MIC and MBC values against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa resistant strains, compared with free CIP. Conclusions: Optimized CIP-loaded chitosan nanoparticles demonstrated improved antibacterial efficacy against resistant strains and good drug delivery properties. These findings highlight the potential of chitosan-based nanocarrier systems to improve the performance of CIP and antibiotic delivery dose-sparing antibiotic strategies.

Background/Objectives: Ciprofloxacin (CIP) is a fluoroquinolone extensively used in hospital settings for the treatment of bacterial infections; however, this antibiotic requires multiple doses because it has poor absorption, rapid elimination, and is ineffective against resistant bacterial strains. Enhanced delivery efficiency could also be used in the dose-sparing techniques, resulting in better antibiotic efficacy. The aim of this study was to improve CIP-loaded chitosan nanoparticles (NPs) and to evaluate their capacity to enhance the antibacterial response in sensitive and resistant bacterial isolates. Methods: CIP-loaded chitosan nanoparticles were fabricated via ionic gelation using sodium tripolyphosphate (TPP) as a crosslinking agent. Formulation parameters, such as CIP concentration and polymer-to-crosslinker ratios, were optimized. The obtained nanoparticles were evaluated for particle size, polydispersity index, zeta potential, entrapment efficiency, morphology, stability, and in vitro release studies. Antibacterial efficacy was evaluated by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against standard and ciprofloxacin-resistant clinical isolates. Results: Successful optimization of these formulations allowed the preparation of stable nanoparticles that ranged from 38.39 to 115.07 nm, highlighting the role of both the formulation composition and polymer-to-crosslinker ratios on the size of the nanoparticles. The formulation exhibits a drug entrapment efficiency of 84.1% and uniform particulate size (38.39 ± 0.63 nm), which were optimized due to the polymer and crosslinker ratios. These nanoparticles showed a slow release of the drug over 220 h, and minimal size instability was noted after 28 days. Encapsulation of CIP resulted in enhanced antibacterial activity, yielding 2–4-fold reductions in MIC and MBC values against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa resistant strains, compared with free CIP. Conclusions: Optimized CIP-loaded chitosan nanoparticles demonstrated improved antibacterial efficacy against resistant strains and good drug delivery properties. These findings highlight the potential of chitosan-based nanocarrier systems to improve the performance of CIP and antibiotic delivery dose-sparing antibiotic strategies.