Antimicrobial properties of spray-dried cellulose nanocrystals and metal oxide-based nanoparticles-in-microspheres

Spray-dried nanoparticle-in-microsphere formulations, composed of aluminum oxide nanoparticles (NPs), zinc oxide, zinc oxide NPs and cellulose nanocrystals (CNCs), with potent antimicrobial and antibiofilm activity against Gram-negative and Gram-positive bacteria are reported. The study highlights the role of matrix compositions (ratios) in manipulating metal oxide biomaterials' antimicrobial properties and toxicity. The antimicrobial activity of nanoparticle-in-microsphere was higher than each raw material used. A formulation composed of CNCs (weight % >= 0.75%) and an equal weight % of aluminum oxide and zinc oxide NPs (similar to 0.25% per type of NPs) produced the highest antimicrobial and antibiofilm activity. Interestingly, the toxicity of these formulations, tested against peripheral blood mononuclear cells, was very minimal (<= 500 mu g/ml) and significantly lower than the toxicity of the metal oxide NPs when tested alone. Nanoparticles-in-microspheres with low toxicity and high antimicrobial properties could be employed in target drug delivery to bypass antibiotics.

Automated summary

Spray-dried nanoparticle-in-microsphere formulations composed of aluminum oxide nanoparticles, zinc oxide, zinc oxide nanoparticles, and cellulose nanocrystals are reported to have potent antimicrobial and antibiofilm activity against various bacteria. The study emphasizes the importance of matrix compositions in manipulating the antimicrobial properties and toxicity of metal oxide biomaterials. The formulations showed higher antimicrobial activity compared to individual raw materials, and a specific formulation with CNCs, aluminum oxide, and zinc oxide nanoparticles exhibited the highest antimicrobial and antibiofilm activity. Importantly, these formulations also had minimal toxicity when tested against blood cells. Thus, low-toxicity and high antimicrobial nanoparticle-in-microsphere formulations could be used for targeted drug delivery and reducing the use of antibiotics.