As one of the most valuable vehicle-based Internet of Things (IoT) applications, Vehicular Ad-hoc Networks (VANETs) have received extensive attention since it was proposed. In order to ensure the ...safety of VANETs and improve the communication efficiency between moving vehicles and different Roadside Units (RSUs), some handover authentication protocols for VANETs have been proposed. However, the existing protocols have some problems such as excessive computation overhead, untraceable malicious messages, and the inability to resist RSU captured attacks. To solve the above problems, we propose a blockchain-based protocol to achieve Vehicle to Infrastructure (V2I) authentication, V2I handover authentication, and Vehicle to Vehicle (V2V) broadcasting authentication. The advantages of our protocol are: (1) It achieves lightweight V2I handover authentication and V2V broadcast authentication, dynamic anonymity strategy and embedding strategy of pseudo-identity and vehicle feature are used to guarantee anonymity and traceability simultaneously; (2) The announcement can be broadcasted verifiably without the help of transportation infrastructure (e.g., RSU) or the Trusted Authority (TA); and (3) The Physically Unclonable Functions (PUF) technology is used to resist RSU captured attacks. We use formal security proof under random oracle model to prove the security of the proposed protocol. Compared with related V2I handover authentication protocols, our protocol can resist RSU captured attacks and other various known attacks. The sum of first and handover authentication efficiency of our protocol is 37.93% higher than the previous most effective protocol while maintaining the same level of communication and storage costs.
The combination of highly sensitive electrochemiluminescence (ECL) techniques with localized surface plasmon resonance (LSPR) effect can achieve the highly sensitive and specific detection in the ...analytical and biosensing applications. However, how to effectively improve the electromagnetic field intensity is an unresolved issue. Herein, we have developed an ECL biosensor based on sulfur dots and Au@Ag nanorod array architecture. Firstly, the high luminescent sulfur dots with ionic liquid capping (S dots (IL) have been prepared as the new ECL emitter. The ionic liquid greatly improved the conductivity of sulfur dots in the sensing process. Furthermore, Au@Ag nanorods array structure was constructed on the electrode surface by the evaporation induced self-assembly. On the one hand, the LSPR of Au@Ag nanorods was more significant than that of good nanomaterial due to the plasma hybridization and the competition between free electrons and oscillating electrons. On the other hand, nanorods array structure had strong electromagnetic field intensity as hot spots due to the surface plasmon coupling ECL effect (SPC-ECL) effect. Therefore, the Au @Ag nanorods array architecture not only greatly enhanced the ECL intensity of sulfur dots, but also changed the ECL signals into polarized emission. Finally, the constructed polarized ECL sensing system was used to detect the mutated BRAF DNA in the eluent of thyroid tumor tissue. The biosensor showed the linear range from 100 fM to 10 nM with a detection limit of 20 fM. The satisfactory results demonstrated that the developed sensing strategy had great potential in the clinical diagnosis of BRAF DNA mutation in thyroid cancer.
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•The polarized SPC-ECL sensor based on Au@Ag nanorods array was developed.•Nanorods array had strong electromagnetic field intensity as hot spots due to the SPC-ECL effect.•The sensor was used to detect BRAF gene in the eluent of thyroid tumor tissue.
The Internet of things is playing more and more important role in smart healthcare, smart grids, and smart transportation, and using wireless sensor network (WSN), we can easily obtain and transmit ...information. However, the data security and users’ privacy are the biggest challenges for WSN because sensor nodes have low computing power and low storage capacity and are easy to be captured, and wireless networks are vulnerable. In 2021, Shuai et al. proposed a lightweight three-factor anonymous authentication scheme for WSN. However, we found that their protocol is vulnerable to stolen-verifier attack, modification of messages’ attack, and no perfect forward secrecy. Then, a new three-factor anonymous authentication scheme using elliptic curve cryptography (ECC) is proposed. Through informal and formal security analyses, our scheme can resist various known attacks and maintains low computational complexity.
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•Magnetic multi-walled carbon nanotubes were prepared for neonicotinoids extraction.•The adsorbent exhibits superiority in adsorption capacity over other adsorbents.•A field-enhanced ...sample stacking-CE way was developed for analyzing neonicotinoids.•The MSPE/CE method can realize detecting neonicotinoid residue in actual samples.
In this study, magnetic multi-walled carbon nanotubes (MMWCNTs) were prepared by a one-pot solvothermal method. And they were used as the adsorbent of magnetic solid-phase extraction (MSPE) to extract NEOs. MMWCNTs exhibit good adsorption performance toward NEOs. The adsorption capacities for imidacloprid, thiacloprid, and acetamiprid are 18.4, 25.9, and 18.4 mg g−1, respectively. Also, the adsorption process takes 20 min. The adsorption isotherm fitted to the Langmuir model and the adsorption kinetics was well described by the pseudo-second-order kinetic model. Moreover, the adsorption mechanism was discussed. The MMWCNTs-based MSPE method was combined with field-enhanced sample stacking-capillary electrophoresis (FESS-CE) to realize the sensitive detection of NEOs. The detection limits of NEOs in honey and bottled green tea beverage samples ranged from 7.63 to 16.7 ng g−1. The recoveries were in the range of 84.5 ± 3.2 % to 99.2 ± 1.6 %, with relative standard deviations less than 5.5 %, suggesting the feasibility of the method in actual samples.
The emergence of multidrug resistance (MDR) and extensive drug resistance (XDR) in Klebsiella pneumoniae strains has posed great threats to conventional antibiotics. Previous studies have shown that ...plant-derived flavonoids have inhibitory functions against pathogens. However, in K. pneumoniae, the antibacterial activity of different flavonoids against growth and biofilm formation remains a mystery. The aim of the present study was to evaluate the antioxidant abilities of different flavonoids, to screen active ingredients and to identify their inhibitory effects on K. pneumoniae growth and biofilm formation. In total, 10 flavonoids representing 4 major categories were screened and used in this study. The antioxidant capacity of each flavonoid was evaluated through a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. Rutin showed the highest level of free radical scavenging capacity, followed by kaempferol, luteolin, quercetin, apigenin, hesperidin, sinensetin, naringenin, naringin and 3,5,6,7,8,3′,4′-heptamethoxyflavone. The inhibitory effects of rutin and naringin on bacterial growth were also compared. The lowest MICs of rutin were found against K. pneumoniae ATCC700603 (1024 μg/mL) and E. coli ATCC25922 (512 μg/mL). However, the MBICs were not found. Rutin showed strong inhibitory ability against both the growth curve and biofilm production. The expression profiles of 15 biofilm-related genes were analyzed in biofilm cells both with and without rutin treatment. The luxS gene and wabG gene were downregulated significantly by rutin treatment. Correlation analysis showed that mrkA gene expression was positively correlated with biofilm biomass accumulation. Our study indicated that biofilm production is correlated with the expression of several genes rather than one. MrkA gene expression was positively correlated with biofilm biomass accumulation. Our study screened rutin as a potential agent to inhibit K. pneumoniae biofilm formation.
•Rutin showed strong inhibitory effect on planktonic cell growth in K. pneumoniae.•Rutin significantly decreased biofilm production when the concentration was higher than 256 μg/mL.•The expression of luxS gene and wabG gene was down-regulated after rutin treatment in strong biofilm producing K. pneumoniae.•Biofilm production might be correlated with the expression of several genes rather than one.•Rutin might be a potential agent to inhibit K. pneumoniae biofilm formation.
People can access and obtain services from smart home devices conveniently through fog-enabled smart home environments. The security and privacy-preserving authentication protocol play an important ...role. However, many proposed protocols have one or more security flaws. In particular, almost all the existing protocols for the smart home cannot resist gateway compromised attacks. The adversary can not only know the user’s identity but also launch impersonation attacks. Designing a provable secure authentication protocol that avoids all known attacks on smart homes is challenging. Recently Guo et al. proposed an authentication scheme based on symmetric polynomials in the fog-enabled smart home environment. However, we found that their scheme suffers from gateway compromised attack, desynchronization attack, mobile device loss/stolen and attack, and has no untraceability and perfect forward secrecy. Therefore, we adopt a Physical Unclonable Function (PUF) to resist gateway compromised attack, adopt Elliptic Curve Diffie–Hellman (ECDH) key exchange protocol to achieve perfect forward secrecy, and propose a secure and privacy-preserving authentication protocol, which is provably secure under the random oracle model. According to the comparisons with some related protocols, the proposed protocol has better security and transmission efficiency with the same computation cost level.
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•CrI3/As vdWHs are investigated deeply on why magnetic stability is substantially enhanced.•Curie temperature TC = 75.9 K, enhanced by 73.3 % compared with CrI3, can be ...achieved.•Compression strain can lead to TC up to 111.3 K due to particular magnetic coupling.•Such vdWHs also features the excellent mechanical and property.
CrI3 monolayer has attracted much attention, but it holds a very low magnetic stability, with Curie temperature (TC) of 45 K, seriously limiting the practical applications. To find solutions for this issue, we construct CrI3/As vdW heterstructures (vdWHs). Calculations show that such vdWHs are half-semiconductor with excellent mechanical property and TC of 75.9 K, improved by 73.3 % compared with CrI3 monolayer. Due to a weak orbital hybridization and coupling occurring between As layer and Iin atom-layer upon vdW interactions, the potential well of interfacial Iin atom-layer would become shallower, which make electron flow out from Iin atoms and magnetic moments increased for Cr and Iin atoms, in turn, the ferromagnetic (FM) coupling in Cr-Iin-Cr superexchange magnetic coupling channel is strengthened. Particularly, the magnetic stability can be significantly raised by compression strain, leading TC up to 111.3 K, which is caused by super-exchange interactions of both Cr-Iin-Cr and Cr-As-Cr channels, and magnetic proximity effects increased further. For light absorption, the red-shifted absorption edge relative to CrI3 monolayer and high absorption peak appearing in visible and infrared region allow heterstructures absorbing solar energy in a wider range. Such a phenomenon can be further strengthened by compression strain.
High-quality DNA is an important guarantee to start downstream experiments in many biological and medical research areas. Magnetic particle-based DNA extraction methods from blood mainly depend on ...electrostatic adsorption in a low-pH environment. However, the strong acidic environment can influence the DNA stability. Herein, a polydopamine-functionalized magnetic particle (PDA@Fe3O4)-based protocol was developed for DNA extraction from whole blood samples. In the protocol, Mg2+ and Ca2+ were utilized to bridge the adsorption of DNA by PDA@Fe3O4 via the metal-mediated coordination. Isopropanol was found to efficiently promote DNA adsorption by triggering the change of the conformation of DNA from B-form to more compact A-form. In 50 % isopropanol solution, the DNA adsorption efficiency was nearly 100 % in the presence of 0.5 mM Ca2+ or 1.5 mM Mg2+. The role of metal ions and isopropanol in DNA adsorption was explored. The protocol averts the strong acidic environment and PCR inhibitors, such as high concentrations of salt or polyethylene glycol. It demonstrates superiority in DNA yield (59.13 ± 3.63 ng μL−1) over the commercial kit (27.33 ± 4.98 ng μL−1) and phenol-chloroform methods (37.90 ± 0.47 ng μL−1). In addition, to simplify the operastion, an automated nucleic acid extraction device was designed and fabricated to extract whole genomic DNA from blood. The feasibility of the device was verified by extracting DNA from cattle and pig blood samples. The extracted DNA was successfully applied to discriminate the beef authenticity by a duplex PCR system. The results demonstrate that the DNA extraction protocol and the automated device have great potential in blood samples.
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•PDA@Fe3O4 was used to purify DNA from blood based on metal-mediated coordination.•Isopropanol promotes DNA adsorption by triggering the change of DNA conformation.•The protocol demonstrates absolute superiority in DNA yield over other methods.•An automated device was fabricated to simplify DNA extraction.•The platform combined with PCR was applied to identify beef authenticity.
This study aimed to identify the role and relationship with efflux pump of biofilm formation in Klebsiella pneumoniae. Sixty-one K. pneumoniae clinical isolates were collected between January and ...June of 2017 from the affiliated hospital of southwest medical university in Luzhou, China. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) were determined using broth microdilution method. Crystal violet (CV) staining and confocal laser scanning microscope (CLSM) were used to monitor biofilm formation. Efflux pump expression was investigated qualitatively and quantitatively by polymerase chain reaction (PCR) and reverse transcriptase quantitative PCR (RT-qPCR). Crystal violet staining was performed to evaluate the effect of efflux pump inhibitor carbonyl cyanide m-chlorophenyl hydrazine (CCCP) on K. pneumoniae biofilms. Our results showed that crystal violet staining and CLSM had good consistency in biofilm detection. Biofilm formation was an independent biological behavior of the strain and measured at 24 h was reasonable. Biofilms up-regulated antimicrobial resistance and expression of efflux pump gene acrA, emrB, oqxA, and qacEΔ1 in K. pneumoniae. CCCP inhibited biofilms but dose-dependent effect was obvious. Altogether, our data demonstrates that biofilm formation, as well as its interaction with efflux pump, promotes antimicrobial resistance in K. pneumoniae.
•Biofilms up-regulated antimicrobial resistance and expression of efflux pump in K. pneumoniae.•Efflux pumps inhibitor CCCP had obvious dose-dependent effect on biofilms.•CCCP above the working concentration inhibited biofilm biomass in K. pneumoniae.•Biofilms might be feedbackly enhanced upon low CCCP concentration.•Biofilm and efflux pump mutually promote each other's role in unspecific resistance of K. pneumoniae.
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