SARS-CoV-2, the virus that causes the disease COVID-19, remains
viable on solids for periods of up to 1 week, so one potential
route for human infection is via exposure to an infectious dose
from a solid. We have fabricated and tested a coating that is
designed to reduce the longevity of SARS-CoV-2 on solids. The
coating consists of cuprous oxide (Cu
2
O) particles
bound with polyurethane. After 1 h on coated glass or stainless
steel, the viral titer was reduced by about 99.9% on average
compared to the uncoated sample. An advantage of a
polyurethane-based coating is that polyurethane is already used
to coat a large number of everyday objects. Our coating adheres
well to glass and stainless steel as well as everyday items that
people may fear to touch during a pandemic, such as a doorknob,
a pen, and a credit card keypad button. The coating performs
well in the cross-hatch durability test and remains intact and
active after 13 days of being immersed in water or after
exposure to multiple cycles of exposure to the virus and
disinfection.
The
ongoing COVID-19 pandemic has created a need for coatings that
reduce infection from SARS-CoV-2 via surfaces. Such a coating could
be used on common touch surfaces (e.g., door handles and railings)
to reduce both disease transmission and fear of touching objects.
Herein, we describe the design, fabrication, and testing of a cupric
oxide anti-SARS-CoV-2 coating. Rapid loss of infectivity is an important
design criterion, so a porous hydrophilic coating was created to allow
rapid infiltration of aqueous solutions into the coating where diffusion
distances to the cupric oxide surface are short and the surface area
is large. The coating was deposited onto glass from a dispersion of
cuprous oxide in ethanol and then thermally treated at 700 °C
for 2 h to produce a CuO coating that is ≈30 μm thick.
The heat treatment oxidized the cuprous oxide to cupric oxide and
sintered the particles into a robust film. The SARS-CoV-2 infectivity
from the CuO film was reduced by 99.8% in 30 min and 99.9% in 1 h
compared to that from glass. The coating remained hydrophilic for
at least 5 months, and there was no significant change in the cross-hatch
test of robustness after exposure to 70% ethanol or 3 wt % bleach.
This equivalence, randomized, clinical trial aimed to compare the postoperative pain of root canal therapy (RCT) with pulpotomy with mineral trioxide aggregate (PMTA) or calcium-enriched mixture (PCEM) in permanent mature teeth. In seven academic centers, 550 cariously exposed pulps were included and randomly allocated into PMTA (n = 188), PCEM (n = 194), or RCT (n = 168) arms. Preoperative “Pain Intensity” (PI) on Numerical Rating Scale and postoperative PIs until day 7 were recorded. Patients’ demographic and pre-/intra-/postoperative factors/conditions were recorded/analysed. The arms were homogeneous in terms of demographics. The mean preoperative PIs were similar (P=0.998), the mean sum PIs recorded during 10 postoperative intervals were comparable (P=0.939), and the trend/changes in pain relief were parallel (P=0.821) in all study arms. The incidences of preoperative moderate-severe pain in RCT, PMTA, and PCEM arms were 56.5%, 55.7%, and 56.7%, which after 24 hours considerably decreased to 13.1%, 10.6%, and 12.9%, respectively (P=0.578). The time span of endodontic procedures was statistically different; RCT = 69.73, PMTA = 35.37, and PCEM = 33.62 minutes (P<0.001). Patients with greater preoperative pain, symptomatic apical periodontitis, or presence of PDL widening suffered more pain (P=0.002, 0.035, and 0.023, resp.); however, other pre-/intra-/postoperative factors/conditions were comparable. Pulpotomy with MTA/CEM and RCT demonstrate comparable and effective postoperative pain relief.
The COVID-19 pandemic had a major impact on life in 2020 and 2021. One method of transmission occurs when the causative virus, SARS-CoV-2, contaminates solids. Understanding and controlling the interaction with solids is thus potentially important for limiting the spread of the disease. We review work that describes the prevalence of the virus on common objects, the longevity of the virus on solids, and surface coatings that are designed to inactivate the virus. Engineered coatings have already succeeded in producing a large reduction in viral infectivity from surfaces. We also review work describing inactivation on facemasks and clothing, and discuss probable mechanisms of inactivation of the virus at surfaces.
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