Microbial Fabricated Nanosystems: Applications in Drug Delivery and Targeting

Novel Biological-Based Strategy for Synthesis of Green Nanochitosan and Copper-Chitosan Nanocomposites: Promising Antibacterial and Hematological Agents

Two novel samples of nanoparticles based on chitosan were greenly synthesized using pomegranate peel extract. The extract served as a nanoparticle precursor, facilitating the precipitation of nanosized chitosan through the ionic gelation method. Additionally, by mixing the green chitosan nanoparticles with copper ions, a nanoscale composite of chitosan and copper oxide was also produced. Structural and morphological investigations (FTIR, XRD, SEM, EDX, and TGA analyses) were performed for greenly synthesized chitosan nanoparticles and their copper oxide composite to determine all the significant characteristics of those nanoparticles. In addition, both samples were tested using some biological investigations, such as antimicrobial activity and hematological effects. The antimicrobial tests yielded promising results for both the green chitosan nanoparticles and the CuO composite when tested using two bacterial strains and two fungal strains. Moreover, the results showed that using a similar concentration of both green-based chitosan samples resulted in a slightly larger inhibition zone and a lower minimum inhibition concentration (MIC) for the copper oxide chitosan composite compared to the chitosan nanoparticles for all microorganisms included in the test. The mean count of blood components (RBCs and platelets), clotting time, and cholesterol levels in three different blood samples were used to indicate the hematological activity of both greenly synthesized nanoparticles. The results verified a slight reduction in blood component count after the addition of green chitosan nanoparticles, but the chitosan copper oxide composite did not have a noticeable effect on the three blood samples. The chitosan nanoparticles were able to cause a considerable reduction in clotting time and cholesterol levels for all blood samples, thus acting as procoagulants. However, the mixing of CuO with chitosan nanoparticles prolonged the rate of clotting in blood samples from hypercholesteremic individuals, and thus, the mixture acted as an anticoagulant agent.

Photosynthetic bacteria-based whole-cell inorganic-biohybrid system for multimodal enhanced tumor radiotherapy

The whole-cell inorganic-biohybrid systems show special functions and wide potential in biomedical application owing to the exceptional interactions between microbes and inorganic materials. However, the hybrid systems are still in stage of proof of concept. Here, we report a whole-cell inorganic-biohybrid system composed of Spirulina platensis and gold nanoclusters (SP-Au), which can enhance the cancer radiotherapy through multiple pathways, including cascade photocatalysis. Such systems can first produce oxygen under light irradiation, then convert some of the oxygen to superoxide anion (•O2-), and further oxidize the glutathione (GSH) in tumor cells. With the combination of hypoxic regulation, •O2- production, GSH oxidation, and the radiotherapy sensitization of gold nanoclusters, the final radiation is effectively enhanced, which show the best antitumor efficacy than other groups in both 4T1 and A549 tumor models. Moreover, in vivo distribution experiments show that the SP-Au can accumulate in the tumor and be rapidly metabolized through biodegradation, further indicating its application potential as a new multiway enhanced radiotherapy sensitizer.

A Dual-Biomineralized Yeast Micro-/Nanorobot with Self-Driving Penetration for Gastritis Therapy and Motility Recovery

Micro-/nanorobots have attracted great interest in the field of drug delivery and treatment, while preparations for biocompatible robots are extremely challenging. Here, a self-driving yeast micro-/nanorobot (Cur@CaY-robot) is designed via dual biomineralization and acid catalysis of calcium carbonate (CaCO₃). Inner nano-CaCO₃ inside yeast cells (CaY) is biomineralized through cell respiration and provides nanoscaffolds for highly encapsulating curcumin (Cur). Meanwhile, the CaCO₃ crystals outside yeast cells (outer-CaCO₃) through uniaxial growth offer an asymmetric power source for self-propelled motility. The Cur@CaY-robot displays an efficient motion in gastric acid, with the potential for deep penetration to the thick gastric mucus, which significantly improves the accumulation of drug agents in the stomach wall tissue for robust gastritis therapy. More importantly, Ca²⁺ cations released from the Cur@CaY-robot also synergistically repair the gastric motility of gastritis mice. Such yeast micro-/nanorobots exhibit desirable biocompatibility and biodegradability with a good loading capacity for drugs. This work provides an idea for the design of micro-/nanorobots through an environmentally friendly biosynthesis strategy for active drug delivery and precise therapy.

Application of biomaterials in the eradication of Helicobacter pylori: A bibliometric analysis and overview

Helicobacter pylori is a prominent cause of gastritis, peptic ulcer, and gastric cancer. It is naturally colonized on the surface of the mucus layer and mucosal epithelial cells of the gastric sinus, surrounded not only by mucus layer with high viscosity that prevents the contact of drug molecules with bacteria but also by multitudinous gastric acid and pepsin, inactivating the antibacterial drug. With high-performance biocompatibility and biological specificity, biomaterials emerge as promising prospects closely associated with H. pylori eradication recently. Aiming to thoroughly summarize the progressing research in this field, we have screened 101 publications from the web of science database and then a bibliometric investigation was performed on the research trends of the application of biomaterials in eradicating H. pylori over the last decade utilizing VOSviewer and CiteSpace to establish the relationship between the publications, countries, institutions, authors, and most relevant topics. Keyword analysis illustrates biomaterials including nanoparticles (NPs), metallic materials, liposomes, and polymers are employed most frequently. Depending on their constituent materials and characterized structures, biomaterials exhibit diverse prospects in eradicating H. pylori regarding extending drug delivery time, avoiding drug inactivation, target response, and addressing drug resistance. Furthermore, we overviewed the challenges and forthcoming research perspective of high-performance biomaterials in H. pylori eradication based on recent studies.

Disrupting biofilm and eradicating bacteria by Ag-Fe3O4@MoS2 MNPs nanocomposite carrying enzyme and antibiotics

In this study, novel multilayered magnetic nanoparticles (ML-MNPs) loaded with DNase and/or vancomycin (Vanc) were fabricated for eliminating multispecies biofilms. Iron-oxide MNPs (IO-core) (500-800 nm) were synthesized via co-precipitation; further, the IO-core was coated with heavy-metal-based layers (Ag and MoS₂ NPs) using solvent evaporation. DNase and Vanc were loaded onto the outermost layer of the ML-MNP formed by nanoporous MoS₂ NPs through physical deposition and adsorption. The biofilms of S. mutans or E. faecalis (or both) were formed in a brain-heart-infusion broth (BHI) for 3 days, followed by treatment with ML-MNPs for 24 h. The results revealed that coatings of Ag (200 nm) and ultrasmall MoS₂ (20 nm) were assembled as outer layers of ML-MNPs successfully, and they formed Ag-Fe₃O₄@MoS₂ MNPs (3-5 μm). The DNase-Vanc-loaded MNPs caused nanochannels digging and resulted in the enhanced penetration of MNPs towards the bottom layers of biofilm, which resulted in a decrease in the thickness of the 72-h biofilm from 48 to 58 μm to 0-4 μm. The sustained release of Vanc caused a synergistic bacterial killing up to 96%-100%. The heavy-metal-based layers of MNPs act as nanozymes to interfere with bacterial metabolism and proliferation, which adversely affects biofilm integrity. Further, loading DNase/Vanc onto the nanoporous-MoS₂-layer of ML-MNPs promoted nanochannel creation through the biofilm. Therefore, DNase-and Vanc-loaded ML-MNPs exhibited potent effects on biofilm disruption and bacterial killing.

Antibacterial, Antifungal, and Antioxidant Activities of Silver Nanoparticles Biosynthesized from Bauhinia tomentosa Linn

The biogenic synthesis of silver nanoparticles (AgNPs) has a wide range of applications in the pharmaceutical industry. Here, we synthesized AgNPs using the aqueous flower extract of Bauhinia tomentosa Linn. Formation of AgNPs was observed using ultraviolet-visible light spectrophotometry at different time intervals. Maximum absorption was observed after 4 h at 420 nm due to the reduction of Ag⁺ to Ag⁰. The stabilizing activity of functional groups was identified by Fourier-transform infrared spectroscopy. Size and surface morphology were also analyzed using scanning electron microscopy. The present study revealed the AgNPs were spherical in form with a diameter of 32 nm. The face-centered cubic structure of AgNPs was indexed using X-ray powder diffraction with peaks at 2θ = 37°, 49°, 63°, and 76° (corresponding to the planes of silver 111, 200, 220, 311), respectively. Energy-dispersive X-ray spectroscopy revealed that pure reduced silver (Ag⁰) was the major constituent (59.08%). Antimicrobial analyses showed that the biosynthesized AgNPs possess increased antibacterial activity (against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), with larger zone formation against S. aureus (9.25 mm) compared with that of E. coli (6.75 mm)) and antifungal activity (against Aspergillus flavus and Candida albican (with superior inhibition against A. flavus (zone of inhibition: 7 mm) compared with C. albicans (zone of inhibition: 5.75 mm)). Inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was found to be dose-dependent with half-maximal inhibitory concentration (IC₅₀) values of 56.77 μg/mL and 43.03 μg/mL for AgNPs and ascorbic acid (control), respectively, thus confirming that silver nanoparticles have greater antioxidant activity than ascorbic acid. Molecular docking was used to determine the mode of antimicrobial interaction of our biosynthesized B. tomentosa Linn flower-powder extract-derived AgNPs. The biogenic AgNPs preferred hydrophobic contacts to inhibit bacterial and fungal sustainability with reducing antioxidant properties, suggesting that biogenic AgNPs can serve as effective medicinal agents.

State of the Art on Toxicological Mechanisms of Metal and Metal Oxide Nanoparticles and Strategies to Reduce Toxicological Risks

Metal nanoparticles have been extensively investigated for different types of pharmaceutical applications. However, their use has raised some concerns about their toxicity involving the increase of reactive oxygen species causing cellular apoptosis. Therefore, in this review we summarize the most relevant toxicity mechanisms of gold, silver, copper and copper oxide nanoparticles as well as production methods of metal nanoparticles. Parameters involved in their toxicity such as size, surface charge and concentration are also highlighted. Moreover, a critical revision of the literature about the strategies used to reduce the toxicity of this type of nanoparticles is carried out throughout the review. Additionally, surface modifications using different coating strategies, nanoparticles targeting and morphology modifications are deeply explained.