henhao
Sign in
Molecular BiologybioRxiv
Preprint

A simple magnetic nanoparticles-based viral RNA extraction method for efficient detection of SARS-CoV-2

Zhen ZhaoiD, Haodong CuiiD, Wenxing Song, Xiaoling Ru, Wenhua ZhouiD, Xue‐Feng YuiD

PDFDOI
Post to X
Threads on XPost to BlueskyThreads on Bluesky
In-depth full-text digest available · Jump to digest ↓

Abstract

1The ongoing outbreak of the novel coronavirus disease 2019 (COVID-19) originating from Wuhan, China, draws worldwide concerns due to its long incubation period and strong infectivity. Although RT-PCR-based molecular diagnosis techniques are being widely applied for clinical diagnosis currently, timely and accurate diagnosis are still limited due to labour intensive and time-consuming operations of these techniques. To address the issue, herein we report the synthesis of poly (amino ester) with carboxyl groups (PC)-coated magnetic nanoparticles (pcMNPs), and the development of pcMNPs-based viral RNA extraction method for the sensitive detection of COVID-19 causing virus, the SARS-CoV-2. This method combines the lysis and binding steps into one step, and the pcMNPs-RNA complexes can be directly introduced into subsequent RT-PCR reactions. The simplified process can purify viral RNA from multiple samples within 20 min using a simple manual method or an automated high-throughput approach. By identifying two different regions (ORFlab and N gene) of viral RNA, a 10-copy sensitivity and a strong linear correlation between 10 and 105 copies of SARS-CoV-2 pseudovirus particles are achieved. Benefitting from the simplicity and excellent performances, this new extraction method can dramatically reduce the turn-around time and operational requirements in current molecular diagnosis of COVID-19, in particular for the early clinical diagnosis.

02 /Specification & Classification

Click any tag to browse matching papers
Citations
219
OpenAlex Topics

In-depth summary

✦ Multi-agent verified full-text synthesis

Claude Opus 5.5 · xhigh effort · 17 Oct 2026 · from the full text of version 1 (27 Feb 2020)

Carboxyl-polymer-coated magnetic beads bind lysate RNA in one step and go straight into RT-PCR, detecting 10 pseudovirus copies with a linear response from 10 to 10^5 copies.

Silica spin-column RNA extraction, the common front end for SARS-CoV-2 RT-PCR, needs separate lysis, binding, washing and elution with repeated centrifugation, which is slow, contamination-prone and hard to automate. The method here merges lysis and binding, drops the elution step by feeding the bead-RNA complex into the reaction, and runs on a standard automated extractor.

Key results

  1. ShownUsing N gene pseudovirus standards spiked into serum, the workflow detects down to 10 copies and gives a linear Ct response across the 10-fold dilution series from 10 to 10^5 copies, with conventional and elution-free protocols behaving alike.

    Ten-fold dilution series from 10 to 10^5 copies: detection limit 10 copies, correlation coefficient R2 = 0.999 between log particle number and Ct, with about 3 cycles between neighbouring curves against a theoretical 3.3 for a 10-fold dilution. Direct RT-PCR gave a similar limit and linearity. · Sensitivity and dynamic range of pcMNPs-based…

  2. ShownThe bead-RNA complex can be put into the RT-PCR reaction without eluting, which loses no sensitivity relative to eluted material and amplifies as efficiently as template spiked straight into the mix.

    With 10^5 pseudovirus copies in 200 μL serum, ORF1ab Ct was slightly lower without elution than with it, possibly because only half the eluate is carried into the conventional reaction; no detectable difference in amplification efficiency versus the positive control, suggesting no carried-over PCR inhibitors. · Applications of pcMNPs in the detection of…

  3. ShownThe protocol transfers to a commercial magnetic-rod extraction platform using a program set from the manual protocol, and the two viral targets agree.

    On an NP968-C system handling up to 32 parallel samples in 96-well plates, amplification curves closely matched the positive control and the manual elution-free run; N gene results agreed with the ORF1ab results in both manual and automated formats. No breakage or leakage of the particles was seen at the most vigorous shaking setting. · Automated viral RNA extraction based on pcMNPs; Development of an automated protocol for RNA…

  4. ShownThe particles are small, well dispersed and strongly negatively charged after polymer coating, and capture most RNA from the combined lysis/binding mix within minutes.

    Average diameter 10.22 ± 2.8 nm by dynamic light scattering with an approximately 3 nm silica shell; zeta potential moves from −4.82 ± 0.54 mV (bare) and 20.57 ± 0.71 mV (silica-coated) to −38.67 ± 0.84 mV after coating. More than 90% of 2 μg RNA was adsorbed by 20 μg of particles within 10 min, and magnetic capture finished within 30 s. · Synthesis and characterization of pcMNPs; RNA binding property of pxMNPs

  5. ClaimedThe authors expect the same complexes to work with isothermal amplification such as recombinase polymerase amplification (RPA) and loop-mediated isothermal amplification (LAMP) for point-of-care testing.

    Stated in the conclusions; no isothermal amplification experiment is reported in this text. · 5 Conclusions

Methods, data and reproducibility

Magnetic nanoparticles were silica-coated, amino-functionalised, then coated with a carboxyl-bearing poly(amino ester) and characterised by electron microscopy, light scattering, zeta potential and infrared spectroscopy. Extraction is one lysis/binding incubation, magnetic collection and an ethanol wash, then either elution or direct transfer of the particle-RNA complex into one-step RT-PCR for ORF1ab and N.

  • SARS-CoV-2 pseudovirus particles (Zeesan Biotech) serially diluted in fetal calf serum as standards, down to 10 copies in 200 μL · SARS-CoV-2 pseudovirus · n = 10 to 10^5 copies per sample
  • Serum without pseudovirus as negative control, and reaction mix spiked with virus as positive control
  • RNA binding assay with purified RNA incubated with the coated particles in lysis/binding buffer · n = 2 μg RNA with 20 μg particles
Methods & tools
pcMNPs (carboxyl polymer-coated magnetic nanoparticles), VetMAX-Plus One-Step RT-PCR Kit, Bio-Red real-time PCR detection system, NP968-C automatic nucleic acid extraction system, transmission electron microscopy, dynamic light scattering, FTIR spectroscopy
Reagents & environment
Reagent suppliers, buffer compositions, thermal cycling conditions and instrument models are given; primer and probe sequences, the automated program and supplementary figures are referenced but not present in this text.
Reproducibility gaps
No code, data or sequence repository links appear in the text, and the referenced tables and figures (primer and probe sequences, optimisation data, automated program) are not included.
Limitations (3)
  • Negative controls sometimes produced amplification signals, though far later than 40 cycles; the authors say primer and probe design may need further optimisation to rule out false positives. · stated by the authors
  • Only pseudovirus particles spiked into fetal calf serum were tested; no patient specimens such as respiratory swabs, and no clinical sensitivity or specificity, are reported in this text. · noted in this summary
  • Two claims lack supporting measurements in this text: the comparison with a commercial kit is one unquantified sentence with no yield or Ct data, and the abstract's 20 min purification time is never timed in the results. · noted in this summary

Who should read:Read this if you run or automate RT-PCR viral testing and want a bead chemistry that collapses lysis, binding and elution into a workflow that feeds the beads straight into the reaction.

Reproducibility ledger

Nobody has reported trying to reproduce this paper yet. Did you replicate an experiment or run the code? Your report saves the next lab a week.

Sign in to file a reproducibility report.

Related papers

Similarity Map
SelectedSame fieldCross-field
THISWee '20Kalnina '20Bruce '20Wozniak '20Sentmanat '20Mallmann '20
81% semantic matchMicrobiology
S. K. Wee, S. P. Sivalingam, E. P. H. Yap·bioRxiv·Apr 17, 2020