Effective screening of infectious
diseases requires a fast, cheap,
and population-scale testing. Antigen pool testing can increase the
test rate and shorten the screening time, thus being a valuable approach
for epidemic prevention and control. However, the overall percent
agreement (OPA) with polymerase chain reaction (PCR) is one-half to
three-quarters, hampering it from being a comprehensive method, especially
pool testing, beyond the gold-standard PCR. Here, a multiantibodies
transistor assay is developed for sensitive and highly precise antigen
pool testing. The multiantibodies capture SARS-CoV-2 spike S1 proteins
with different configurations, resulting in an antigen-binding affinity
down to 0.34 fM. The limit of detection reaches 3.5 × 10–17 g mL–1SARS-CoV-2 spike S1 protein
in artificial saliva, 4–5 orders of magnitude lower than existing
transistor sensors. The testing of 60 nasopharyngeal swabs exhibits
∼100% OPA with PCR within an average diagnoses time of 38.9
s. Owing to its highly precise feature, a portable integrated platform
is fabricated, which achieves 10-in-1 pooled screening for high testing
throughput. This work solves the long-standing problem of antigen
pool testing, enabling it to be a valuable tool in precise diagnoses
and population-wide screening of COVID-19 or other epidemics in the
future.
Rapid screening of infected individuals
from a large population
is an effective means in epidemiology, especially to contain outbreaks
such as COVID-19. The gold standard assays for COVID-19 diagnostics
are mainly based on the reverse transcription polymerase chain reaction,
which mismatches the requirements for wide-population screening due
to time-consuming nucleic acid extraction and amplification procedures.
Here, we report a direct nucleic acid assay by using a graphene field-effect
transistor (g-FET) with Y-shaped DNA dual probes (Y-dual probes).
The assay relies on Y-dual probes modified on g-FET simultaneously
targeting ORF1ab and N genes of SARS-CoV-2 nucleic acid, enabling
high a recognition ratio and a limit of detection (0.03 copy μL
–1
) 1–2 orders of magnitude lower than existing
nucleic acid assays. The assay realizes the fastest nucleic acid testing
(∼1 min) and achieves direct 5-in-1 pooled testing for the
first time. Owing to its rapid, ultrasensitive, easily operated features
as well as capability in pooled testing, it holds great promise as
a comprehensive tool for population-wide screening of COVID-19 and
other epidemics.
Dithieno[3,2-b:2′,3′-d]pyrrole (DTP) derivatives are one of the most important organic photovoltaic materials due to better π-conjugation across fused thiophene rings.
The existing electrochemical biosensors lack controllable
and intelligent
merit to modulate the sensing process upon external stimulus, leading
to challenges in analyzing a few copies of biomarkers in unamplified
samples. Here, we present a self-actuated molecular-electrochemical
system that consists of a tentacle and a trunk modification on a graphene
microelectrode. The tentacle that contains a probe and an electrochemical
label keeps an upright orientation, which increases recognition efficiency
while decreasing the pseudosignal. Once the nucleic acids are recognized,
the tentacles nearby along with the labels are spontaneously actuated
downward, generating electrochemical responses under square wave voltammetry.
Thus, it detects unamplified SARS-CoV-2 RNAs within 1 min down to
4 copies in 80 μL, 2–6 orders of magnitude lower than
those of other electrochemical assays. Double-blind testing and 10-in-1
pooled testing of nasopharyngeal samples yield high overall agreement
with reverse transcription-polymerase chain reaction results. We fabricate
a portable prototype based on this system, showing great potential
for future applications.
The core plays a crucial role in achieving high performance of linear hole transport materials (HTMs) toward the perovskite solar cells (PSCs). Most studies focused on the development of fused heterocycles as cores for HTMs. Nevertheless, nonfused heterocycles deserve to be studied since they can be easily synthesized. In this work, we reported a series of low-cost triphenylamine HTMs (M101-M106) with different nonfused cores. Results concluded that the introduced core has a significant influence on conductivity, hole mobility, energy level, and solubility of linear HTMs. M103 and M104 with nonfused oligothiophene cores are superior to other HTMs in terms of conductivity, hole mobility, and surface morphology. PSCs based on M104 exhibited the highest power conversion efficiency of 16.50% under AM 1.5 sun, which is comparable to that of spiro-OMeTAD (16.67%) under the same conditions. Importantly, the employment of M104 is highly economical in terms of the cost of synthesis as compared to that of spiro-OMeTAD. This work demonstrated that nonfused heterocycles, such as oligothiophene, are promising cores for high performance of linear HTMs toward PSCs.
Accurate and population-scale screening technology is crucial in the control and
prevention of COVID-19, such as pooled testing with high overall testing efficiency.
Nevertheless, pooled testing faces challenges in sensitivity and specificity due to
diluted targets and increased contaminations. Here, we develop a graphene field-effect
transistor sensor modified with triple-probe tetrahedral DNA framework (TDF) dimers for
10-in-1 pooled testing of SARS-CoV-2 RNA. The synergy effect of triple probes as well as
the special nanostructure achieve a higher binding affinity, faster response, and better
specificity. The detectable concentration reaches 0.025–0.05 copy
μL
–1
in unamplified samples, lower than that of the reverse
transcript-polymerase chain reaction. Without a requirement of nucleic-acid
amplification, the sensors identify all of the 14 positive cases in 30 nasopharyngeal
swabs within an average diagnosis time of 74 s. Unamplified 10-in-1 pooled testing
enabled by the triple-probe TDF dimer sensor has great potential in the screening of
COVID-19 and other epidemic diseases.
Fused-ring thiophene
compounds emerged as an important type of
building blocks for organic dyes toward the dye-sensitized solar cells
(DSSCs) because of their good charge transfer and light-harvesting
properties. Nevertheless, some fused-ring thiophenes have a lack of
desired alkyl chains or side alkyl chains, which may induce a severe
charge recombination in devices. In this work, the hex-1-en-1-ylbenzene
(HEYB) unit was introduced in two new fused-ring thiophene organic
dyes (M60 and M59), resulting in a modest dihedral angle (∼36°)
between the donor and spacer in dyes. The effect of the HEYB unit
on optical, electrochemical, and photovoltaic properties has been
investigated by comparing with their congeners (M42 and M58) without
the HEYB unit. It is found that introduction of the HEYB unit in arylamine
donor enhanced the driving force for dye regeneration and beneficial
for suppressing dye aggregation as well as reducing the charge recombination.
Device performance characteristics demonstrate that introduction of
the HEYB unit in the arylamine donor is a feasible strategy toward
enhancing the performance of fused-ring thiophene organic dyes. Benefiting
from this strategy, a dye-sensitized solar cell employing the M60
photosensitizer and a cobalt electrolyte exhibits a good power conversion
efficiency of 9.75% measured under the 100 mW cm–2, simulated AM1.5 sunlight.
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