The antibiofilm and collagen-stabilizing effects of proanthocyanidin as an auxiliary endodontic irrigant

AIM

To evaluate the antibiofilm effect of proanthocyanidin (PA) solution as an irrigant against Enterococcus faecalis (E. faecalis) and its influence on the mechanical properties and biodegradation resistance of demineralized root dentine.

METHODOLOGY

Enterococcus faecalis were introduced into human root dentine tubules by a serial centrifugation method and grown for 1 week. Dentine blocks infected with 1-week-old E. faecalis biofilms were treated with the following irrigants: sterile water (control), 2% chlorhexidine (CHX), 2% PA, 5% PA and 10% PA. After treatment, the live and dead bacteria proportions within E. faecalis biofilms were analysed using confocal laser scanning microscopy. To evaluate the biostability of fully demineralized dentine treated by the aforementioned irrigants, the elastic modulus and hydroxyproline release of human dentine incubated in collagenase solution were tested at baseline, after irrigant treatment and after biodegradation, respectively. Furthermore, the surface chemical bond of demineralized dentine collagen treated by various irrigants was characterized by X-ray photoelectron spectroscopy (XPS). Statistical analysis was performed using one-way anova and Tukey's post hoc multiple comparisons with the significance level at 5%.

RESULTS

The proportion of dead E. faecalis volume was significantly higher in the PA and CHX groups than that in the control group (P < 0.05). PA irrigation significantly increased the mechanical properties of demineralized dentine (P < 0.05), and the effect was enhanced with increasing PA concentration. CHX and PA groups had significantly less elasticity loss and hydroxyproline release (P < 0.05). The biomodification of dentine collagen by PA was verified by increased C-O/C-N peak percentage under C1s and C-O peak percentage under O1s narrow-scan XPS spectra.

CONCLUSIONS

Proanthocyanidin killed E. faecalis within biofilms and enhanced the biostability of the collagen matrix of demineralized root dentine. It might be used as an auxiliary endodontic irrigant with antibiofilm and collagen-stabilizing effects.

Earth's orbital chirality and driving force of biomolecular evolution

In our recent studies, it has been suggested that both symmetry breaking (violation) and biological rhythms could be caused by the natural rhythmic right-handed helical force field produced by the Earth's orbital chirality (EOC) (1--3). In this essay, according to the further theoretical and experimental studies, it was suggested that the natural EOC force field could serve as the diving force of biomolecular evolution via the chiral interactions. In addition, the following suggestions also were pointed out: (1) The EOC force field could cause the origin of non-coding repetitive DNA sequences ('Junk DNA') to increase the genomes stability and complexity; (2) The EOC force field could increase the structural order of biological systems via the biomolecular EOC stabilization energy effects; (3) The biological information could be spontaneously produced by the chiral interactions of the protogenes with the EOC force field.

Periodicity of Earth's orbital chirality and possible mechanism of biological rhythms

Biological rhythms are ubiquitous in living systems from prokaryote to eukaryote on the Earth. So far, the origin of biological rhythms is still a problem. It is suggested here that the periodicity of the Earth's orbital chirality (EOC) could give rise to the periodicity of the chiral helical biomolecular stability and activity, and then generate the biological rhythms in terrestrial living systems. Our experimental results strongly support the theory that the periodic chiral helical EOC force-field should be the power behind the origin of biological rhythms.

Effect of earth's orbital chirality on elementary particles and unification of chiral asymmetries in life on different levels

Life is chirally asymmetric at all scales from microscopic elementary particles to molecular and macroscopic levels. How these chiral asymmetries in life on different levels are unified remains unanswered. It has been demonstrated that both the biomolecular homochirality and biological rhythms can be caused by the right-handed helical force-field of the Earth's orbital chirality (EOC). Similar to the helical biomolecules (1), it is here suggested that the right-handed EOC force-field could make the right-handed elementary particles more stable than their left-handed enantiomers to result in the symmetry violation of elementary particles, and the EOC could also cause the macroscopic predominant selection of right-handed asymmetries of living objects (e.g. the helical seashells and plants). Our studies indicated that the weak force in weak interaction may only be a form of the EOC force-field at the microscopic particle level, and the chiral asymmetries in life on various levels could be unified by the natural right-handed EOC force-field. Moreover, the chiral and quantum effects, time, mass, rhythms and relativity could also be unified by the interaction of the EOC force-field with chiral motions and structures under certain conditions.

Effect of chiral helical force field on molecular helical enantiomers and possible origin of biomolecular homochirality

Biomolecular homochirality means that the amino acids in proteins, and sugars in nucleic acids, occur in one form: amino acids in L-form and sugars in D-form. So far, the reason why these molecules have such uniform chirality is not known. In this paper, it is suggested that a net natural chiral right-handed helical force field, produced by the Earth's orbital chirality (EOC), could affect the stability of molecular helical enantiomers and make the right-handed helical enantiomers more stable than their left-handed enantiomers, so terrestrial biological systems must select both right-handed helical nucleic acids based on D-sugars, and proteins based on L-amino acids. In given conditions, the maximum energy difference between biomolecular helical enantiomers (deltaEmax=/Eleft-Eright/) caused by the EOC may be calculated theoretically to be in the order: B-DNA > A-RNA > A-DNA >> alpha-protein > beta-protein. Our experimental results strongly supported the hypothesis that the EOC could cause the spontaneous selection and amplification of right-handed helical enantiomers and could be the origin of homochirality on the Earth.