pH-dependent antibacterial effects on oral microorganisms through pure PLGA implants and composites with nanosized bioactive glass

Abstract

Biomaterials made of biodegradable poly(-hydroxyesters) such as poly(lactide-co-glycolide) (PLGA) are known to decrease the pH in the vicinity of the implants. Bioactive glass (BG) is being investigated as a counteracting agent buffering the acidic degradation products. However, in dentistry the question arises whether an antibacterial effect is rather obtained from pure PLGA or from BG/PLGA composites, as BG has been proved to be antimicrobial. In the present study the antimicrobial properties of electrospun PLGA and BG45S5/PLGA fibres were investigated using human oral bacteria (specified with mass spectrometry) incubated for up to 24 h. BG45S5 nanoparticles were prepared by flame spray synthesis. The change in colony-forming units (CFU) of the bacteria was correlated with the pH of the medium during incubation. The morphology and structure of the scaffolds as well as the appearance of the bacteria were followed bymicroscopy. Additionally, we studied if the presence of BG45S5 had an influence on the degradation speed of the polymer. Finally, it turned out that the pH increase induced by the presence of BG45S5 in the scaffold did not last long enough to show a reduction in CFU. On the contrary, pure PLGA demonstrated antibacterial properties that should be taken into consideration when designing biomaterials for dental applications. AbstractBiomaterials made of biodegradable poly(α-hydroxyesters) like poly(lactide-co-glycolide) (PLGA) are known to decrease the pH in the vicinity of the implants. Bioactive glass (BG) is being investigated as a counteracting agent buffering the acidic degradation products.However, in dentistry the question arises whether an antibacterial effect is rather obtained from pure PLGA or from BG/PLGA composites, as BG has been proved antimicrobial. In the present study the antimicrobial properties of electrospun PLGA and BG45S5/PLGA fibres were investigated using human oral bacteria (specified with mass spectrometry) incubated for up to 24 h. BG45S5 nanoparticles were prepared by flame spray synthesis. The change in colony-forming units (CFU) of the bacteria was put into correlation with the pH of the medium during incubation. Morphology and structure of the scaffolds as well as the appearance of the bacteria were followed by microscopy. Additionally, we studied if the presence of BG45S5 had an influence on the degradation speed of the polymer. Finally, it turned out that the pH increase induced by BG45S5 presence in the scaffold did not last long enough to show a reduction in CFU. On the contrary, pure PLGA demonstrated antibacterial properties that should be taken into consideration when designing biomaterials for dental applications.

Evaluation of selected properties of a new root repair cement containing surface pre-reacted glass ionomer fillers

“…However, the incorporation of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 13 bioactive glass fillers into relatively bioinert materials has gained popularity in recent years as an attempt to achieve more specific biological responses such as inducing antibacterial action [28] or promoting a particular cell response [29]. The antibacterial test used in this study was a modified direct contact test, which is a common antibacterial test used in the endodontic literature to test the antibacterial properties of root cements [4] and sealers [30].…”

Characterization of nanostructured ureteral stent with gradient degradation in a porcine model

“…PLGA degrades faster generally. [26][27][28][29] Auge et al reports that the human urinary milieu is different from that of animals, whereas urinalyses indicate that the urine pH values of animals are close to those of humans. 30 The degradation products of PLGA are acidic, and are easily metabolized in and eliminated from the body via the Krebs cycle.…”

Degradability, biocompatibility, and osteogenesis of biocomposite scaffolds containing nano magnesium phosphate and wheat protein both in vitro and in vivo for bone regeneration

“…22 It is known that the release of acidic degradation by-products from some degradable polymers could lead to inflammatory responses in vivo, and many methods have been tried to control the pH decrease during the degradation of these polymers. 23,24 In this study, it was found that there was gradually a decrease of pH in the solution containing WP (from 7.40 to 7.10), indicating that some acidic products (amino acids) might be produced from WP degradation during the soaking process. However, the pH for MWC scaffolds showed a slight increase from the initial value of 7.40 to 7.76 during the soaking process.…”