Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella

Design of new hydrolyzed collagen-modified magnetic nanoparticles to capture pathogens

Enrichment and diagnosis tools for pathogens currently available are time consuming, thus the development of fast and highly sensitive alternatives is desirable. In this study, a novel approach was described that enables selective capture of bacteria expressing hydrolyzed collagen-binding adhesins with hydrolyzed collagen-coated magnetic nanoparticles (MNPs). This platform could be useful to shorten the time needed to confirm the presence of a bacterial infection. MNPs were synthesized by a simple two-step approach through a green co-precipitation method using water as solvent. These MNPs were specifically designed to interact with pathogenic bacteria by establishing a hydrolyzed collagen-adhesin linker. The bacterial capture efficacy of hydrolyzed collagen MNPs (H-Coll@MNPs) for bacteria expressing collagen binding adhesins was 1.3 times higher than that of arginine MNPs (Arg@MNPs), herein used as control. More importantly, after optimization of the MNP concentration and contact time, the H-Coll@MNPs were able to capture 95% of bacteria present in the samples. More importantly, the bacteria can be enriched within 30 min and the time for bacterial identification is effectively shortened in comparison to the "gold standard" in clinical diagnosis. These results suggest that H-Coll@MNPs can be used for the selective isolation of specific bacteria from mixed populations present, for example, in biological samples.

Inactivation of Non-Enveloped Viruses and Bacteria by an Electrically Charged Disinfectant Containing Meso-Structure Nanoparticles via Modification of the Genome

INTRODUCTION

A previous study demonstrated the virucidal effect of an electrically charged disinfectant (CAC-717), which contains meso-structure nanoparticles, on enveloped viruses (influenza viruses). However, the effect of CAC-717 on other microorganisms and the mechanisms by which CAC-717 inactivates the microorganisms remain unclear. In this study, CAC-717 was further evaluated in terms of its biocidal and virucidal activity as well as its effect on bacterial and viral nucleic acids.

METHODS

The inactivation effects of CAC-717 against various microorganisms [non-enveloped virus, feline calicivirus (FCV); bacteria, Salmonella enterica and Escherichia coli] were investigated by comparing the viral titer of the medium tissue culture infectious dose (TCID50) and the D value (estimated treatment time required to reduce the number of microorganisms by 90%). Furthermore, the effects of CAC-717 on viral and bacterial genomic RNA/DNA were examined using a polymerase chain reaction (PCR).

RESULTS

Treatment of an equal volume of CAC-717 with cell lysate infected with a non-enveloped virus, feline calicivirus (FCV), reduced the TCID50. Viral titer dropped below the detection limit after 2 min of treatment. The D value of FCV was 0.256 min (average of multiple endpoint D values) and endpoint D value was 0.341 min. The D value for E. coli and S. enterica was 0.290 min and 0.080 min (average of multiple endpoint D values), respectively and the endpoint D value was 0.545 min and 0.054 min, respectively. In addition, PCR showed the inhibition of nucleic acid amplification of the RNA and DNA genome of FCV and bacteria, respectively.

CONCLUSION

Our findings suggest that CAC-717 inactivates viruses and bacteria by modifying the viral and bacterial nucleic acids.

Applications of Iron Oxide-Based Magnetic Nanoparticles in the Diagnosis and Treatment of Bacterial Infections

Diseases caused by bacterial infections, especially drug-resistant bacteria have seriously threatened human health throughout the world. It has been predicted that antimicrobial resistance alone will cause 10 million deaths per year and that early diagnosis and therapy will efficiently decrease the mortality rate caused by bacterial infections. Considering this severity, it is urgent to develop effective methods for the early detection, prevention and treatment of these infections. Until now, numerous efforts based on nanoparticles have been made to detect and kill pathogenic bacteria. Iron oxide-based magnetic nanoparticles (MNPs), as potential platforms for bacteria detection and therapy, have drawn great attention owing to their magnetic property. These MNPs have also been broadly used as bioimaging contrast agents and drug delivery and magnetic hyperthermia agents to diagnose and treat bacterial infections. This review therefore overviews the recent progress on MNPs for bacterial detection and therapy, including bacterial separation and enrichment in vitro, bacterial infection imaging in vivo, and their therapeutic activities on pathogenic bacteria. Furthermore, some bacterial-specific targeting agents, used to selectively target the pathogenic bacteria, are also introduced. In addition, the challenges and future perspective of MNPs for bacterial diagnosis and therapy are given at the end of this review. It is expected that this review will provide a better understanding toward the applications of MNPs in the detection and therapy of bacterial infections.

Efficient recovery and enrichment of infectious rotavirus using separation with antibody-integrated graphite-encapsulated magnetic nanobeads produced by argon/ammonia gas plasma technology

Background

Rotavirus is the representative cause of severe acute gastroenteritis in young children. A characteristic feature of rotavirus is low infectious dose and robustness of the virion, suggesting sanitation and hygiene will have little impact. Thus, development of a vaccine should be given priority. Efficient capture of infectious viruses is an important step in generating a vaccine. Previously, antibody-integrated magnetic nanobeads (MNBs) have been developed for virus capture. This study examines the applicability of this method for infectious rotavirus recovery and enrichment.

Materials and methods

Graphite-encapsulated MNBs were treated with radio frequency (RF) excited Ar/NH₃ gas mixture plasma to introduce amino groups onto their surfaces. Rotavirus viral protein 7 (VP7) antibody was attached to the surface of MNBs via these amino groups using a coupling agent, N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP). The antibody-integrated MNBs were incubated with rotavirus-infected cell lysate and then separated from the supernatant by applying a magnetic field. After thorough washing, rotavirus was recovered and enrichment analysis done by polymerase chain reaction (PCR), immunochromatography, and an infection analysis using MA104 cells.

Results and discussion

Immunochromatography and PCR indicate that anti-rotavirus antibody-integrated MNPs efficiently capture rotavirus with the capsid protein and viral RNA. The estimated recovery rate was 80.2% by PCR and 90.0% by infection analysis, while the concentrating factor was 7.9-fold by PCR and 6.7-fold by infection analysis. In addition, the absence of non-specific binding to the antibody-integrated MNPs was confirmed using anti-dengue virus antibody-integrated MNBs as a negative control.

Conclusion

These results suggest that this capture procedure is a useful tool for recovery and enrichment of infectious rotavirus. Moreover, when combined with a suitable virus assay this capture procedure can increase the sensitivity of rotavirus detection. Therefore, this capture method is a valuable tool for generating vaccines as well as for developing sensitive detection systems for viruses.

Crucial roles of reactive chemical species in modification of respiratory syncytial virus by nitrogen gas plasma

The exact mechanisms by which nanoparticles, especially those composed of soft materials, are modified by gas plasma remain unclear. Here, we used respiratory syncytial virus (RSV), which has a diameter of 80-350nm, as a model system to identify important factors for gas plasma modification of nanoparticles composed of soft materials. Nitrogen gas plasma, generated by applying a short high-voltage pulse using a static induction (SI) thyristor power supply produced reactive chemical species (RCS) and caused virus inactivation. The plasma treatment altered the viral genomic RNA, while treatment with a relatively low concentration of hydrogen peroxide, which is a neutral chemical species among RCS, effectively inactivated the virus. Furthermore, a zero dimensional kinetic global model of the reaction scheme during gas plasma generation identified the production of various RCS, including neutral chemical species. Our findings suggest the nitrogen gas plasma generates RCS, including neutral species that damage the viral genomic RNA, leading to virus inactivation. Thus, RCS generated by gas plasma appears to be crucial for virus inactivation, suggesting this may constitute an important factor in terms of the efficient modification of nanoparticles composed of soft materials.

Rapid Detection Strategies for the Global Threat of Zika Virus: Current State, New Hypotheses, and Limitations

The current scenario regarding the widespread Zika virus (ZIKV) has resulted in numerous diagnostic studies, specifically in South America and in locations where there is frequent entry of travelers returning from ZIKV-affected areas, including pregnant women with or without clinical symptoms of ZIKV infection. The World Health Organization, WHO, announced that millions of cases of ZIKV are likely to occur in the USA in the near future. This situation has created an alarming public health emergency of international concern requiring the detection of this life-threatening viral candidate due to increased cases of newborn microcephaly associated with ZIKV infection. Hence, this review reports possible methods and strategies for the fast and reliable detection of ZIKV with particular emphasis on current updates, knowledge, and new hypotheses that might be helpful for medical professionals in poor and developing countries that urgently need to address this problem. In particular, we emphasize liposome-based biosensors. Although these biosensors are currently among the less popular tools for human disease detection, they have become useful tools for the screening and detection of pathogenic bacteria, fungi, and viruses because of their versatile advantageous features compared to other sensing devices. This review summarizes the currently available methods employed for the rapid detection of ZIKV and suggests an innovative approach involving the application of a liposome-based hypothesis for the development of new strategies for ZIKV detection and their use as effective biomedicinal tools.

Capture of dengue viruses using antibody-integrated graphite-encapsulated magnetic beads produced using gas plasma technology

Despite significant advances in medicine, global health is threatened by emerging infectious diseases caused by a number of viruses. Dengue virus (DENV) is a mosquito-borne virus, which can be transmitted to humans via mosquito vectors. Previously, the Ministry of Health, Labour and Welfare in Japan reported the country's first domestically acquired case of dengue fever for almost 70 years. To address this issue, it is important to develop novel technologies for the sensitive detection of DENV. The present study reported on the development of plasma-functionalized, graphite-encapsulated magnetic nanoparticles (GrMNPs) conjugated with anti-DENV antibody for DENV capture. Radiofrequency wave-excited inductively-coupled Ar and ammonia gas plasmas were used to introduce amino groups onto the surface of the GrMNPs. The GrMNPs were then conjugated with an antibody against DENV, and the antibody-integrated magnetic beads were assessed for their ability to capture DENV. Beads incubated in a cell culture medium of DENV-infected mosquito cells were separated from the supernatant by applying a magnetic field and were then washed. The adsorption of DENV serotypes 1–4 onto the beads was confirmed using reverse transcription-polymerase chain reaction, which detected the presence of DENV genomic RNA on the GrMNPs. The methodology described in the present study, which employed the plasma-functionalization of GrMNPs to enable antibody-integration, represents a significant improvement in the detection of DENV.

Capturing and concentrating adenovirus using magnetic anionic nanobeads

We recently demonstrated how various enveloped viruses can be efficiently concentrated using magnetic beads coated with an anionic polymer, poly(methyl vinyl ether-maleic anhydrate). However, the exact mechanism of interaction between the virus particles and anionic beads remains unclear. To further investigate whether these magnetic anionic beads specifically bind to the viral envelope, we examined their potential interaction with a nonenveloped virus (adenovirus). The beads were incubated with either adenovirus-infected cell culture medium or nasal aspirates from adenovirus-infected individuals and then separated from the supernatant by applying a magnetic field. After thoroughly washing the beads, adsorption of adenovirus was confirmed by a variety of techniques, including immunochromatography, polymerase chain reaction, Western blotting, and cell culture infection assays. These detection methods positively identified the hexon and penton capsid proteins of adenovirus along with the viral genome on the magnetic beads. Furthermore, various types of adenovirus including Types 5, 6, 11, 19, and 41 were captured using the magnetic bead procedure. Our bead capture method was also found to increase the sensitivity of viral detection. Adenovirus below the detectable limit for immunochromatography was efficiently concentrated using the magnetic bead procedure, allowing the virus to be successfully detected using this methodology. Moreover, these findings clearly demonstrate that a viral envelope is not required for binding to the anionic magnetic beads. Taken together, our results show that this capture procedure increases the sensitivity of detection of adenovirus and would, therefore, be a valuable tool for analyzing both clinical and experimental samples.