Development of antimicrobial hybrid mesoporous silver phosphate–pectin microspheres for control release of levofloxacin

• Stable spherical Ag3PO4 microparticles were chemically synthesized in presence of pectin under controlled physicochemical conditions.
• The hybrid Ag3PO4–pectin microparticles allow to load levofloxacin in a single device defined upon therapeutic requirements.
• The synthesis of Ag3PO4 pectin microparticles is made under soft condition (Green Chemistry) and does not require further purification.
• Antimicrobial properties of Ag3PO4–pectin microparticles displayed enhanced antimicrobial activity against Gram (+) and Gram (−) bacteria.
• The silver phosphate pectin microparticle showed antibiotic controlled release.

Pectin was used as nucleation agent in the synthesis of spherical mesoporous Ag3PO4 microspheres for the development of dual antimicrobial carrier containing a fluoroquinolone. The hybrid Ag3PO4–pectin microspheres were characterized by biophysical methods using optical, scanning and transmission electronic microscopies, X-ray diffraction and energy dispersive analysis, differential scanning calorimetry, laser diffraction, and molecular gas adsorption (Brunauer–Emmett–Teller). Scanning electron microscopy (SEM) images of silver phosphate microspheres without pectin displayed heterogeneous surface, bimodal size distribution between 0.9–1.0 μm and 1.5–1.8 μm with 20% and 25% population yield respectively and high amount of salt detritus. Meanwhile, SEM microphotographies of silver phosphate microspheres synthesized in presence of pectin showed a drastic change of particle morphology, homogenous surface, narrow size particle distribution in the 1.3–1.5 μm range with 90% population yield, 20–30% pore size increase and without debris. X-ray diffraction analysis of silver phosphate microspheres showed the same crystal profile in presence or absence of pectin suggesting no changes in the crystalline structure of Ag3PO4 by the addition of the biopolymer was made. Effect of silver phosphate hybrid microspheres loaded with levofloxacin tested against Escherichia coli and Staphylococcus aureus showed strong bactericidal activity compared with the bacteriostatic effect of free levofloxacin. The results are suggesting that hybrid Ag3PO4–pectin microspheres containing levofloxacin can be used as effective antimicrobial against several microorganisms, making them applicable to diverse medical devices and for antimicrobial control systems. The Ag3PO4–pectin hybrid microspheres are advantageous since they are synthesized by green chemistry methodology under standard laboratory conditions, do not requiring purification steps, the technique is highly reproducible and they are available for drug loading and specific target tailoring. The main advantage of Ag3PO4–pectin microspheres is the synergic antimicrobial activity of the silver ion and the antibiotic in the same microdevice acting as biocide matrix and also as carrier for levofloxacin.

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