1.Nanomaterials for Virus Detection
Viruses are contagious, reproduced within the infected host cells and spreading among people to cause diseases. As population density increases, virus transmission is becoming a serious problem in the society today. One effective way to prevent infection is to detect and identify the virus early, for which some rapid and sensitive methods has been developed (Figure 1). Some methods implement the interaction between viral proteins and light or the unique geometry of viral protein shells. One of the most researched methods is based on the use of biochemical interactions.
1930 1950 1970 1980 1990 2000 2010
Figure 1. The onset of nanotechnology in virus detection applications compared with the development of the most common virus detection techniques.
Hemagglutination-inhibition Immunoblotting Assays
Loop-mediated Isothermal Amplification
Nucleic Acid Sequence-based Amplification
Polymerase Chain Reaction
Nanotechnology & Virus Detection
2.Viruses are consisted of two components: 1). the capsid protein that makes up the viral shell, and 2). the nucleic acid that contains genetic information inside the shell (Figure 2). Both components can be used as targets for biochemical detection, and the speciﬁc target determines the type of the biochemical interaction. A typical biochemical mechanism for capturing selective capsid proteins is the use of antigen-antibody interactions. Highly speciﬁc and sensitive antibodies can selectively detect the viral proteins. In nucleic acid detection, complementary sequences can be used to detect viral nucleic acids. The designed oligonucleotides also capture viral target nucleic acids in a highly sensitive and selective manner.
D E F
Figure 2. Virus structures. A, adenovirus; B, inﬂuenza virus; C, tobacco mosaic virus; D, HIV; E, hepatitis virus; F, herpes
Infectious diseases caused by viruses (HIV, inﬂuenza and hepatitis) cause nearly 8 million deaths each year. Early diagnosis is essential to prevent viral spreading at the regional level and to prevent broader damage. Due to the relatively low concentration of target virus particles in body ﬂuids, accurate and rapid detection of such diseases requires highly sensitive biosensors with fast processing time to ensure timely treatment of affected individuals. In addition, limited resources and medical staff in the point-of-care setting can be a major challenge for early diagnosis. Therefore, there is an urgent need for simple, cheap and sensitive diagnostic tools to achieve timely diagnosis of infectious diseases.
Many traditional virus tests (Table 1) do not meet these requirements. The most mature virus detection method is the enzyme-linked immunosorbent assay (ELISA), in which a solid-phase enzyme detects the presence of a speciﬁc substance, such as an antigen. But ELISA is not suitable for rapid diagnosis because it requires speciﬁc laboratory equipment, and typical sample preparation takes four hours or more. Cell culture or plaque analysis is another clinical technique for virus detection and quantiﬁcation.
3.It inoculates potentially infected samples into the host cell layer and observes the unique cytopathic effects. Although sensitive, the analysis of this method usually takes several weeks. In addition, there are several other conventional detection methods, including real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR), hemagglutination, and endpoint dilution. However, all of these rely heavily on diffusion-limited biochemical ampliﬁcation to indicate the presence of the virus, also requiring long time for analysis and larger sample size. Therefore, these methods cannot guarantee the on-site and instant detection of viral particles to prevent the epidemics.
Table 1. A comparison of different virus detection techniques.
Technique Detection Principle Time Cost Remarks
Nanomaterials have unique optical, electrical, magnetic and mechanical properties, and are attractive in the ﬁelds of biomedical imaging and clinical diagnosis. In the late 1990s, the ﬁrst application of nanomaterials in virus detection was reported: combining gold nanoparticles with silver staining to detect human papillomavirus in cervical cancer cells. In recent years, nanomaterials including metal nanoparticles (NPs), carbon nanotubes, quantum dots (QDs), upconverting nanoparticles, and polymer nanoparticles are very extensively used for virus detection. One of the most common ways to utilize these nanostructures in virus detection is to develop nanobio hybrid systems that contain one or more biomolecules derived from viruses (e.g., DNA, RNA, antibody, pentabody, antigen or peptide) conjugated to the surface of different forms of the NPs. These systems use the signiﬁcant labeling properties and signal transduction functions of NPs and the speciﬁc activity of conjugated biomolecules to serve as multivalent NP probes. Surprisingly, these virus-speciﬁc NP probes have been used to establish many optical,
Viral Plaque Assay
Measuring virus infective particles
Conventional, simple, poor reproducibility
Virus protein assay
Conventional, simple, poor reproducibility
Virus protein assay
Modern, sensitive, poor reproducibility
Virus protein binding with enzymes
Modern, highly sensitive, good reproducibility
Nucleic acid ampliﬁcation
Modern, highly sensitive, excellent reproducibility
Virus Flow Cytometry
Biophysical method of counting virus particles
Modern, highly sensitive, excellent reproducibility
Selective binding of virus particles, nucleic acids or proteins
Simple and reversible, good reproducibility, highly sensitive and selective
4.ﬂuorescent, electrochemical, and electrical analyses that have been widely reported for single and multiple detection modes. The results of these studies clearly demonstrate the inherent potential of these probes, as well as many advantages over traditional methods in terms of size, performance, speciﬁcity, signal sensitivity, and stability. In addition, these studies have extensively described their applications (as follows) for simple, fast, high-sensitivity, and label-free detection.
All inﬂuenza pandemics in humans are caused by inﬂuenza A virus. In addition, inﬂuenza A virus (IAV) has been reported to infect a wide range of animal species. Currently, among several inﬂuenza viruses classiﬁed according to 17 hemagglutinin (HA) and 10 neuraminidase (NA), H3N2 and H1N1 subtypes are transmitted in humans.
Liu et al . developed an IAV colorimetric immunosensor based on the monoclonal antibody-modiﬁed gold
nanoparticles (mAb-AuNPs). The results of their system relied on the plasmon shift derived from
mAb-AuNPs assembled on the surface of IAV. Under the optimal conditions, this method can detect H3N2 IAV (A/Brisbane/10/2007) with a detection limit of 7.8 HAU. The immunosensor has high speciﬁcity, accuracy, and good stability. It is worth noting that, unlike the classic immunoassay, it is a one-step detection using the mAb-AuNP probe and can be directly observed with the naked eye, without the need for expensive and complicated instruments. In addition, this analysis does not rely on virus and AuNPs cross-linking, but the ordered AuNP structure covering the surface of the virus. That is, this method can be applied to any viral pathogen detection by incorporating appropriate pathogen-speciﬁc antibodies.
Therefore, this method has broad application prospects in clinical diagnosis.
Human activity has caused Dengue virus (DENV) and the major mosquito vectors Aedes spp. to spread to almost every continent since 1970. The infection rate has increased by more than 30 times and has become the most prevalent arbovirus disease in the world. Every year 3.6 billion people are at risk of infection and there are 390 million new cases, most of which are children. In the absence of vaccines or speciﬁc treatments, early detection plays an important role in reducing mortality. Dengue infections have no pathognomonic signs, so diagnostic tools are essential. Vector surveillance plays a key role in dengue detection and outbreak prevention. Current laboratory methods for detecting and diagnosing DENV require highly trained personnel and expensive equipment, which is impractical for routine monitoring and diagnostic uses.
5.Therefore, new technologies are urgently needed to promote and enhance diagnostic and monitoring capabilities in each transmission cycle. Wasik has developed two new biosensors using single-walled carbon nanotube transducers to detect complete DENV or DENV Non-Structural Protein 1 (NS1). Heparin is an analog of the DENV receptor, heparan sulfate proteoglycan and is used as a biological receptor to detect the entire DENV virions in virus culture, which makes the DENV virion detection from compatible samples (such as liquid or tissue samples from monkeys, vector mosquitoes and humans) feasible.
Anti-dengue NS1 monoclonal antibody is a clinically accepted biomarker for DENV infection to detect DENV NS1. The biosensor will enable early detection and diagnosis of diseases in Aedes mosquitoes and human saliva. Both biosensors are selective and sensitive to target analytes in a 10 µL sample in a clinically relevant concentration range, with a detection time of only 10-20 min. Each was designed as a portable, rapid, and inexpensive diagnostic tool and ideal for use by minimally trained personnel in laboratories or other point-of-care locations.
Colloidal semiconductor quantum dots (QDs) have many inherent characteristics, including broad absorption spectra, narrow emission spectra, and excellent photostability, which has promoted their widespread use in various practical medical applications. For example, they have been used: 1) as immunoﬂuorescent probes to detect Her2 breast cancer markers, 2) as signal transduction components in microbial toxin immunoassays and 3) as labels for dynamic studies of cancer cell motility and correlation of metastatic potential.
Respiratory syncytial virus (RSV) is an enveloped negative-sense single-stranded RNA paramyxovirus that is the main cause of lower respiratory tract infections in infants. Recently, RSV is becoming an increasing concern for the elderly and immunocompromised population. Considering the infection cycle of RSV, the virus seems to be an ideal target for studying virus diagnostic methods using QD probes. Fusion proteins
(F) and attachment proteins (G) are incorporated into the surface of host cells, making them the ideal antigenic markers for the presence of RSV. In addition, viral replication provides an inherent ampliﬁcation of these markers over time. Using these aspects of viral infectivity, Elizabeth et al . reported the use of QD to identify and monitor the presence of RSV infection. Their research showed that multiple quantum dot probes can be used to study the spatial distribution of several viral proteins simultaneously throughout the infection phases. Therefore, quantum dots may provide a method for early and rapid detection of viral infections, and open the door to further study of the complex spatial characteristics and cellular transport of viral proteins.
The Ebola epidemic has received much attention and there is an urgent need to develop effective diagnostic methods. The key to detecting lethal viruses is high sensitivity, as early detection of the virus may increase the likelihood of survival. Among many detection sensors, lanthanide-doped upconverting nanoparticles (UCNPs) have become new materials to replace traditional down-shifting probes (organic dyes, quantum dots, etc.). UCNPs have unique biological detection advantages such as low background
ﬂuorescence, small photodamage, high photostability, large anti-Stokes shift, and low toxicity. Tsang et al . proposed a luminescence detection consisting of BaGdF5: Yb / Er upconverting nanoparticles (UCNPs) conjugated with oligonucleotide probes and gold nanoparticles (AuNPs) linked to target Ebola virus oligonucleotides. As a proof of concept, a homogeneous assay was made and tested, showing a detection limit at picomolar level. Luminous resonance energy transfer is attributed to the spectral overlap of upconverting luminescence and the absorption characteristics of AuNPs. In addition, they anchored UCNPs and AuNPs to nanoporous alumina (NAAO) membranes, forming a heterogeneous assay. This has greatly improved the detection limit and showed signiﬁcant value at the femtomolar level. This enhancement is due to an increase in light-matter interactions in the nanopore walls of the entire NAAO membrane.
Speciﬁcity tests show that the nanoprobe is speciﬁc for Ebola virus oligonucleotides. Combinations of UCNPs, AuNPs, and NAAO membranes provides a new strategy for low-cost, fast, and ultra-sensitive detection of different diseases.
Polymer nanoparticles are colloidal particles with sizes between 10 and 1000 nm. The smaller size promotes capillary penetration and cell uptake, increasing the concentration at the target site. Detection of inﬂuenza virus (IFV) in the early stages of the disease is essential for effective anti-inﬂuenza therapy with neuraminidase inhibitors. At the time of infection, sialyloligosaccharide receptors on the surface of
respiratory cells are recognized by IFV hemagglutinin (HA). Matsubara et al . demonstrated the use of poly(glycidyl methacrylate) (PGMA)-coated polystyrene nanoparticles in combination with a sialic acid mimetic peptide to detect the agglutination of IFV. The azido peptide was immobilized on the surface of PGMA-coated nanoparticles by click chemistry. The dynamic light scattering method is used to determine the particle size distribution of the nanoparticles, indicating that in the presence of HA and IFV, the
peptide-conjugated nanoparticles had aggregated. Nanoparticles that conjugate with receptor mimetic peptides may be a useful red blood cell alternative in global surveillance and clinical diagnosis of inﬂuenza.
Tsang, M. K., Ye, W., Wang, G., Li, J., Yang, M., & Hao, J. (2016). Ultrasensitive detection of Ebola virus oligonucleotide based on upconversion nanoprobe/nanoporous membrane system. Acs Nano, 10(1), 598-605.
Matsubara, T., Kubo, A., & Sato, T. (2020). Detection of inﬂuenza virus by agglutination using
nanoparticles conjugated with a sialic acid-mimic peptide. Polymer Journal, 52(2), 261-266.
Bentzen, E. L., House, F., Utley, T. J., Crowe, J. E., & Wright, D. W. (2005). Progression of respiratory syncytial virus infection monitored by ﬂuorescent quantum dot probes. Nano letters, 5(4), 591-595.
Liu, Y., Zhang, L., Wei, W., Zhao, H., Zhou, Z., Zhang, Y., & Liu, S. (2015). Colorimetric detection of inﬂuenza A virus using antibody-functionalized gold nanoparticles. Analyst, 140(12), 3989-3995.
Park, J. E., Kim, K., Jung, Y., Kim, J. H., & Nam, J. M. (2016). Metal nanoparticles for virus detection.
ChemNanoMat, 2(10), 927-936.
Address: 45-1 Ramsey Road, Shirley, NY 11967, USA
For more information,
view our website: www.cd-bioparticles.com