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A novel analysis technique of elements at ambient conditions has been developed. The technique is based on microwave-assisted laser-induced breakdown spectroscopy (MW-LIBS) applied to acoustically levitated samples. The technique has been demonstrated using three solid samples with different properties and compositions. These are ore containing multiple elements (OREAS 520), aluminium oxide (Al₃O₂) and gypsum (CaSO₄·2H₂O). The mass of samples was 21 mg, 23 mg, and 55 mg for gypsum, mineral ore, and Al₃O₂, respectively. Significant signal enhancements were recorded for a variety of elements, using microwave-assisted laser-induced breakdown spectroscopy and levitation (MW-LIBS–Levitation). The signal enhancement for Mn I (403.07 nm), Al I (396.13 nm) and Ca II (393.85 nm) was determined as 123, 46, and 63 times, respectively. Moreover, it was found that MW-LIBS–Levitation minimises the self-absorption of the Ca I (422.67 nm) and Na I (588.99 nm and 589.59 nm) spectral lines. In addition to the signal enhancements, the levitation process produces a spinning motion in the solids with an angular frequency of 7 Hz. This feature benefits laser-based analysis as a fresh sample is introduced at each laser pulse, eliminating the need for the usual mechanical devices. Based on the single-shot analysis, it was found that ∼80% of the laser pulses produced successful MW-LIBS–Levitation detection, confirming an impressive repeatability of the process. This contactless analytical technique can be applied in ambient pressure and temperature conditions with high sensitivity, which can benefit disciplines such as forensics science, isotope analysis, and medical analysis, where the sample availability is often diminutive.

Plant hormones are important in the control of physiological and developmental processes including seed germination, senescence, flowering, stomatal aperture, and ultimately the overall growth and yield of plants. Many currently available methods to quantify such growth regulators quickly and accurately require extensive sample purification using complex analytic techniques. Herein we used ultra-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) to create and validate the prediction of hormone concentrations made using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectral profiles of both freeze-dried ground leaf tissue and extracted xylem sap of Japanese knotweed (Reynoutria japonica) plants grown under different environmental conditions. In addition to these predictions made with partial least squares regression, further analysis of spectral data was performed using chemometric techniques, including principal component analysis, linear discriminant analysis, and support vector machines (SVM). Plants grown in different environments had sufficiently different biochemical profiles, including plant hormonal compounds, to allow successful differentiation by ATR-FTIR spectroscopy coupled with SVM. ATR-FTIR spectral biomarkers highlighted a range of biomolecules responsible for the differing spectral signatures between growth environments, such as triacylglycerol, proteins and amino acids, tannins, pectin, polysaccharides such as starch and cellulose, DNA and RNA. Using partial least squares regression, we show the potential for accurate prediction of plant hormone concentrations from ATR-FTIR spectral profiles, calibrated with hormonal data quantified by UHPLC-HRMS. The application of ATR-FTIR spectroscopy and chemometrics offers accurate prediction of hormone concentrations in plant samples, with advantages over existing approaches.

In this work, a nanogold surface molecularly imprinted polymer spectral probe (AuNP@MIP) for selectively identifying ferrocyanide was prepared under microwave irradiation using nanogold as the core, ferrocyanide as the template ion, methacrylic acid as the monomer, and ethylene glycol dimethacrylate as the cross-linking agent. AuNP@MIP was found to produce a resonance Rayleigh scattering (RRS) peak at 370 nm. When potassium ferrocyanide (K₄Fe(CN)₆) was present, a AuNP@MIP–Fe(CN)₆ complex was formed, producing RRS-energy transfer (RRS-ET). With an increase in ferrocyanide concentration within a certain range, the RRS intensity at 370 nm decreased linearly, and the detection range was 0.02–0.40 μmol L⁻¹, with a detection limit as low as 0.006 μmol L⁻¹ ferrocyanide. This new method has the advantages of simplicity, rapidity, and selectivity when applied for the determination of K₄Fe(CN)₆ in table salt.

In the orthopaedic surgery field, the use of medical implants to treat a patient's bone fracture is nowadays a common practice, nevertheless, it is associated with possible cases of infection. The consequent hardware infection can lead to implant failure and systemic infections, with prolonged hospitalization, time-consuming rehabilitation treatments, and extended antibiotic therapy. Hardware infections are strictly related to bacterial adhesion to the implant, leading to infection occurrence and consequent pH decreasing from physiological level to acid pH. Here, we demonstrate the new strategy to use an orthopaedic implant functionalized with iridium oxide film as the working electrode for the potentiometric monitoring of pH in hardware infection diagnosis. A functional investigation was focused on selecting the implant material, namely titanium, titanium alloy, and stainless steel, and the component, namely screws and implants. After selecting the titanium-based implant as the working electrode and a silver wire as the reference electrode in the final configuration of the smart sensing orthopaedic implant, a calibration curve was performed in standard solutions. An equation equal to y = (0.76 ± 0.02) − (0.068 ± 0.002) x, R² = 0.996, was obtained in the pH range of 4–8. Subsequently, hysteresis, interference, matrix effect, recovery study, and storage stability were investigated to test the overall performance of the sensing device, demonstrating the tremendous potential of electrochemical sensors to deliver the next generation of smart orthopaedic implants.

We design a p-aminothiophenol (pATP) modified Au/ITO chip to determine nitrite ions in lake water by a ratiometric surface-enhanced Raman scattering (SERS) method based on nitrite ions triggering the transformation of pATP to p,p′-dimercaptoazobenzene (DMAB). Intriguingly, by using the SERS peak (at 1008 cm⁻¹) from benzoic ring deforming as an internal standard instead of the traditional peak at 1080 cm⁻¹, the detection sensitivity of the method was improved 10 times.

Antimicrobial resistance poses a serious threat to human health due to the high morbidity and mortality caused by drug-resistant microbial infections. Therefore, the development of rapid, sensitive and selective identification methods is key to improving the survival rate of patients. In this paper, a sandwich-type electrochemical DNA biosensor based on a polyadenine-DNA tetrahedron probe was constructed. The key experimental conditions were optimized, including the length of polyadenine, the concentration of the polyadenine DNA tetrahedron, the concentration of the signal probe and the hybridization time. At the same time, poly-avidin-HRP80 was used to enhance the electrochemical detection signal. Finally, excellent biosensor performance was achieved, and the detection limit for the synthetic DNA target was as low as 1 fM. In addition, we verified the practicability of the system by analyzing E. coli with the MCR-1 plasmid and realized multi-channel detection of the drug resistance genes MCR-1, blaNDM, blaKPC and blaOXA. With the ideal electrochemical interface, the polyA-based biosensor exhibits excellent stability, which provides powerful technical support for the rapid detection of antibiotic-resistant strains in the field.

In this study, a microfluidic-based system utilizing colorimetric loop-mediated isothermal amplification (LAMP) is introduced for the quantitative analysis of nucleic acid targets. This system offers a user-friendly and cost-effective platform for the multiplexed genetic diagnosis of various infectious diseases across multiple samples. It includes time-lapse imaging equipment for capturing images of the microfluidic device during the LAMP assay and a hue-based quantitative analysis software to analyze the LAMP reaction, streamlining diagnostic procedures. An electric pipette was used to simplify the loading of samples and LAMP reagents into the device, allowing easy operation even by untrained individuals. The hue-based analysis software employs efficient image processing and post-processing techniques to calculate DNA amplification curves based on color changes in multiple reaction chambers. This software automates several tasks, such as identifying reaction chamber areas from time-lapse images, quantifying color information within each chamber, correcting baselines of DNA amplification curves, fitting experimental data to theoretical curves, and determining the threshold time for each curve. To validate the developed system, conventional off-chip LAMP assays were conducted with a 25 μL reaction mixture in 0.2 mL polymerase chain reaction (PCR) tubes using a real-time turbidimeter. The results indicated that the threshold time obtained using the colorimetric LAMP assay in the developed system is comparable to that obtained with real-time turbidity measurements in PCR tubes, demonstrating the system's capability for quantitative analysis of target nucleic acids, including those from human herpesviruses.

More than 65% of bacterial infections are caused by biofilms. However, standard biofilm susceptibility tests are not available for clinical use. All conventional biofilm models suffer from a long formation time and fail to mimic in vivo microbial biofilm conditions. Moreover, biofilms make it difficult to monitor the effectiveness of antibiotics. This work creates a powerful yet simple method to form a target biofilm and develops an innovative approach to monitoring the antibiotic's efficacy against a biofilm-associated infection. A paper-based culture platform can provide a new strategy for rapid microbial biofilm formation through capillary action. A combined electrical-electrochemical technique monitors bacterial metabolism rapidly and reliably by measuring microbial extracellular electron transfer (EET) and using electrochemical impedance spectroscopy (EIS) across a microbe-electrode interface. Three representative pathogens, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, form their biofilms controllably within an hour. Within another hour their susceptibilities to three frontline antibiotics with different action modes (gentamicin, ciprofloxacin, and ceftazidime) are examined. Our antibiotic susceptibility testing (AST) technique provides a quantifiable minimum inhibitory concentration (MIC) of those antibiotics against the in vitro biofilm models and characterizes their action mechanisms. The results will have an important positive effect because they provide immediately actionable healthcare information at a reduced cost, revolutionizing public healthcare.

Microparticle rotation is an important process in biomedical engineering, such as biosensors, cell injection or cell morphology. Single particle rotation has been widely investigated, while rotation of particle chains has gained rare attention. In this paper, we utilize a noncontact manipulation method to rotate microparticle chains via electrorotation by designing an octuple-electrode array (OEA). Finite element simulations were conducted for analyzing the desired electrode field and optimizing the structure of microelectrode pairs. The direction of the electric field in the workspace is investigated with different voltage signal inputs through specially designed circuits. In the experiment, microparticles are driven to form several chains in the proposed electrode fields. With the rotation of the electric field, particle chains could be rotated synchronously. Automated rotation and detection of polystyrene microspheres and yeast cell chains are achieved using machine vision technology. Results show that the proposed method could be utilized to rotate ordered microparticles with an appropriate input signal.