TABLE 8.
Other types of nAbts and their associated functions.
| Other types of NPs | NPs | Size/shape | Conjugated antibiotic | Conjugate’s chemistry | Targeted bacteria | Target site | Mechanism of action | Reference |
|---|---|---|---|---|---|---|---|---|
| Nanocomposite (NC) | Ag | Ag 15 ± 5 nm, quasi-spherical | Tetracycline (TC) | Ag chemically binds with amide group of TC | Escherichia coli K12 ATCC 29425 (S), Escherichia coli ST648 (R), Staphylococcus aureus ATCC 25923 (S) | Outer cell membrane | Ag cytotoxicity in bacterial cells with TC as protein synthesis inhibition brings synergistic dual antimicrobial mechanism. | Djafari et al. (2016) |
| Nanosheets | Montmorillonite | 40–120 nm, sheet | Tetracycline (TC) | At low pH, tetracycline absorbs on the external surface by complexation/chelation with Al3+, Fe2+/Fe3+, Si4+, Mg2+ ions. Furthermore, diffuse into interlayer spaces by the cation exchange mechanism. | Escherichia coli, Staphylococcus aureus | Outer cell membrane | Dissolved metal ions release and multivalent cations acquisition overload crossing outer membrane channel. | Chahardahmasoumi et al. (2019); Hohle et al. (2011) |
| Nanomesh | Gold NPs | 5 nm, spherical | Vancomycin (Van), Colistin/Polymyxin E | Using an electrospinning method, the drug’s charge and the functionalization of charged particles within a nanofiber/nanomesh system enable the drug positioning within a mesh. | Escherichia coli | Outer cell membrane | The opposite charge of Gold NPs to the drugs can increase the release from the Nanomesh. Increased burst release of dual drugs diffuses from the mesh in the first few hours and subsequently has different sustained release rates. | Fuller et al. (2019) |
| Hydrocarbon | Norbornene (Nb) NPs | 50 nm, spherical | Vancomycin (Van) | NPs are synthesized by ring-opening metathesis copolymerization (ROMP) of Nb-Van (polyethylene oxide). Amide bond of Van functionalized with Nb by a covalent link on a titanium surface. | Methicillin-resistant Staphylococcus aureus (MRSA BCB8) | Cell wall | The multivalent polymer of the Van-Nb NP system can increase the specific surface and deliver 1.2 × 106 van molecules/NP, such high Van density at a specific site enhances the antibacterial activity. | Pichavant et al. (2016) |
| Solid Lipid (SLNs) | Lipid NPs (L-NPs), Phospholipid NPs (PL NPs) | 125–175 nm, spherical | Penicillin-G (PenG), levofloxacin (Levo) | Two stearoyl chains of alkane-based lipids are connected with the antibiotic’s extended hydroxyl groups. Diacetyl phosphate groups of phospholipids are conjoined with R-O groups of antibiotics. | Methicillin sensitiveStaphylococcus aureus | Cell membrane | PenG-PL NPs can load a high amount of PenG with a rapid release rate. PL part attaches PenG to the cell membrane, thus achieve greater internalization inside the cell, killing intracellular bacteria. | Zhang et al. (2019) |