Enhancing Raman signals from bacteria using dielectrophoretic force between conductive lensed fiber and black silicon.

An osmium-coated lensed fiber (OLF) probe combined with a silver-coated black silicon (SBS) substrate was used to generate a dielectrophoretic (DEP) force that traps bacteria and enables Raman signal detection from bacteria. The lensed fiber coated with a 2-nm osmium layer was used as an electrode for the DEP force and also as a lens to excite Raman signals. The black silicon coated with a 150-nm silver layer was used both as the surface-enhanced Raman scattering (SERS) substrate and the counter electrode. The enhanced Raman signal was collected by the same OLF probe and further analyzed with a spectrometer. For Raman measurements, a drop of bacterial suspension was placed between the OLF probe and the SBS substrate. By controlling the frequency of an AC voltage on the OLF probe and SBS substrate, a DEP force at 1 MHz concentrated bacteria on the SBS surface and removed the unbound micro-objects in the solution at 1 kHz. A bacteria concentration of 6 × 104 CFU/mL (colony forming units per mL) could be identified in less than 15 min, using a volume of only 1 µL, by recording the variation of the Raman peak at 740 cm-1.

A microfluidic microwell device operated by the automated microfluidic control system for surface-enhanced Raman scattering-based antimicrobial susceptibility testing.

Bloodstream infection (BSI) is a serious public health issue worldwide. Timely and effective antibiotics for controlling infection are crucial towards patient outcomes. However, the current culture-based methods of identifying bacteria and antimicrobial susceptibility testing (AST) remain labor-intensive and time-consuming, and are unable to provide early support to physicians in critical hours. To improve the effectiveness of early antibiotic therapy, Surface-enhanced Raman scattering (SERS) technology, has been used in bacterial detection and AST based on its high specificity and label-free features. To simplify sample preparation steps in SERS-AST, we proposed an automated microfluidic control system to integrate all required procedures into a single device. Our preliminary results demonstrated the system can achieve on-chip reagent replacement, bacteria trapping, and buffer exchange. Finally, in-situ SERS-AST was performed within 3.5 h by loading isolates of ampicilin susceptible and resistant E. coli and clear discrimination of two strains under antibiotic treatment was demonstrated. Overall, our system can standardize and simplify the SERS-AST protocol and implicate parallel bacterial detection. This prototypical integration demonstrates timely microbiological support to optimize early antibiotic therapy for fighting bacteremia.

Bacteria encapsulation and rapid antibiotic susceptibility test using a microfluidic microwell device integrating surface-enhanced Raman scattering.

The antibiotic susceptibility test (AST) is a general laboratory procedure for bacterial identification and characterization and can be utilized to determine effective antimicrobials for individual patients. Due to the low bacterial concentration, conventional AST usually requires a prolonged bacterial culture time and a labor-intensive sample pretreatment process. Therefore, it cannot perform timely diagnosis or treatment, which results in a high mortality rate for seriously infected patients. To address this problem, we developed a microfluidic microwell device integrating surface-enhanced Raman scattering (SERS) technology, or the so called the Microwell-SERS system, to enable a rapid and high-throughput AST. Our results show that the Microwell-SERS system can successfully encapsulate bacteria in a miniaturized microwell with a greatly increased effective bacteria concentration, resulting in a shorter bacterial culture time. By attaching a microchannel onto the microwell, a smooth liquid and air exchange can purify the surrounding buffer and isolate bacteria in an individual microwell for independent SERS measurement. For proof-of-concept, we demonstrated a 2 h AST on susceptible and resistant E. coli and S. aureus with a concentration of 103 CFU mL-1 in the Microwell-SERS system, whereas the previous SERS-AST method required 108 CFU mL-1 bacterial suspension droplets dispensing on a SERS substrate. Based on the above features, we envision that the Microwell-SERS system could achieve highly sensitive, label-free, bacteria detection and rapid AST to enable timely and accurate bacterial infection disease diagnosis.

Percutaneous vertebroplasty for the treatment of osteoporotic vertebral compression fractures: a preliminary report.

BACKGROUND: This report assesses the efficacy and safety of percutaneous vertebroplasty for osteoporotic vertebral compression fractures and reports on preliminary results of its use. METHODS: The technique was used on 50 patients with 86 painful vertebral fractures, all of which had failed to respond to earlier conservative medical treatment. The technique involves percutaneous puncture of the involved vertebra via a transpedical approach followed by injection of polymethyl methacrylate (PMMA) into the compressed vertebra. Patients were asked to quantity their degree of pain on Huskisson's visual analogue scale (VAS) to assess the clinical symptoms and surgical results. RESULTS: The procedures were technically successful in all patients, and no complications relating to either the anesthesia or the surgical procedure were reported. The quantity of PMMA injected per vertebral body varied from 2.5 to 12 ml according to both the position of the damaged vertebra(e) and the severity of the compression fracture. Pain, as assessed on the Huskisson's VAS, decreased from 82 +/- 15 mm at the baseline to 37 +/- 22 mm on the first postoperative day, and 32 +/- 19 mm at 1 month. Reductions in pain from the baseline to the first day and to 1 month were both statistically significant (p < 0.05). All patients were able to return to their previous activity and quality of life. CONCLUSION: Through the expertise and attention of experienced surgeons, percutaneous vertebroplasty appears to provide a very good surgical choice for patients with vertebral compression fractures, as this surgical procedure is able to eliminate the risk of major spinal surgery, and through prompt pain relief, may provide early mobilization and rehabilitation for elderly polymorbid patients.