Objective
Chitosan nanoparticle (nanochitosan) has a broad antimicrobial spectrum against diverse pathogenic microorganisms. However, its effect on dental caries-associated microorganisms, such as
Streptococcus mutans
and
Candida albicans
is yet to be explored. These microorganisms are known for causing early childhood caries. Therefore, this study was aimed at investigating nanochitosan inhibition capacity against dual-species biofilms of
S. mutans
and
C. albicans.
In this study, nanochitosan antimicrobial activity is reported against mono and dual biofilm species of
S. mutans
and/or
C. albicans
at 3 and 18 h incubation time. Nanochitosan inhibition capacity was observed through biofilm mass quantity and cell viability.
Results
The present study successfully synthesized nanochitosan with average diameter of approximately 20–30 nm, and also established dual-species biofilms of
S. mutans
and
C. albicans
in vitro. With nanochitosan treatment, the cell viability of both microorganisms significantly decreased with the increasing concentration of nanochitosan. There was no significant decrease in biofilm mass both in the dual and single-species biofilms after 3 h of incubation. However, greater inhibition of biofilm was observed at 18 h incubation.
Docking analysis of propolis's natural compound was successfully performed against SARS-CoV-2 main protease (Mpro) and spike protein subunit 2 (S2). Initially, the propolis's protein was screened using chromatography analysis and successfully identified 22 compounds in the propolis. Four compounds were further investigated, i.e., neoblavaisoflavone, methylophiopogonone A, 3′-Methoxydaidzin, and genistin. The binding affinity of 3′-Methoxydaidzin was −7.7 kcal/mol, which is similar to nelfinavir (control), while the others were −7.6 kcal/mol. However, we found the key residue of Glu A:166 in the methylophiopogonone A and genistin, even though the predicted binding energy slightly higher than nelfinavir. In contrast, the predicted binding affinity of neoblavaisoflavone, methylophiopogonone A, 3′-Methoxydaidzin, and genistin against S2 were −8.1, −8.2, −8.3, and −8.3 kcal/mol, respectively, which is far below of the control (pravastatin, −7.3 kcal/mol). Instead of conventional hydrogen bonding, the π bonding influenced the binding affinity against S2. The results reveal that this is the first report about methylophiopogonone A, 3′-Methoxydaidzin, and genistin as candidates for anti-viral agents. Those compounds can then be further explored and used as a parent backbone molecule to develop a new supplementation for preventing SARS-CoV-2 infections during COVID-19 outbreaks.
The PAN/TiO
2
/Ag nanofibers membrane for air filtration
media was successfully synthesized with electrospinning method. The
morphology, size, and element percentage of the nanofiber were characterized
by a scanning electron microscopy–energy dispersive spectroscopy,
while X-ray fluorescence and FTIR were used to observe the chemical
composition. The water contact angle and UV–vis absorption
were measured for physical properties. Performance for air filtration
media was measured by pressure drop, efficiency, and quality factor
test. TiO
2
and Ag have been successfully deposited in nonuniform
570 nm PAN/TiO
2
/Ag nanofibers. The nanofiber membrane had
hydrophilic surface after TiO
2
and Ag addition with a water
contact angle of 34.58°. UV–vis data showed the shifting
of absorbance and band gap energy of nanofibers membrane to visible
light from 3.8 to 1.8 eV. The 60 min spun PAN/TiO
2
/Ag nanofibers
membrane had a 96.9% efficiency of PM
2.5
, comparable to
results reported in previous studies. These properties were suitable
to be applied on air filtration media with photocatalytic activity
for self-cleaning performance.
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