Implantable Aptamer-Graphene Microtransistors for Real-Time Monitoring of Neurochemical Release in Vivo.

The real-time monitoring of neurochemical release in vivo plays a critical role in understanding the biochemical process of the complex nervous system. Current technologies for such applications, including microdialysis and fast-scan cyclic voltammetry, suffer from limited spatiotemporal resolution or poor selectivity. Here, we report a soft implantable aptamer-graphene microtransistor probe for real-time monitoring of neurochemical release. As a demonstration, we show the monitoring of dopamine with nearly cellular-scale spatial resolution, high selectivity (dopamine sensor >19-fold over norepinephrine), and picomolar sensitivity, simultaneously. Systematic benchtop evaluations, ex vivo experiments, and in vivo studies in mice models highlight the key features and demonstrate the capability of capturing the dopamine release dynamics evoked by pharmacological stimulation, suggesting the potential applications in basic neuroscience studies and studying neurological disease-related processes. The developed system can be easily adapted for monitoring other neurochemicals and drugs by simply replacing the aptamers functionalized on the graphene microtransistors.

Eradication by surfactant irrigation of Staphylococcus aureus from infected complex wounds.

Treatment of infected orthopaedic hardware usually requires the removal of the appliance. When the device is removed and immediately replaced, persistent infection frequently complicates this exchange procedure. We modeled the exchange procedure in rats by passing a wire suture through a posterior spinous process and then contaminating the wound with Staphylococcus aureus. We then investigated whether a sequence of surfactant enriched irrigation solutions (Castile soap followed by benzalkonium chloride, sequential surfactant irrigation) had a greater capacity to eradicate Staphylococcus aureus from the experimental wound than did the standard wound irrigant, normal saline. When we left the wire in place through the 2-week course of the study, sequential surfactant irrigation showed only a modest advantage over normal saline (staphylococci recovered from 39% versus 58% of wound cultures respectively). Simple removal of the wire 24 hours after implantation and bacterial contamination prevented wound infection in most animals (with the wire removed, 38% of the animals remained infected versus 85% with the wire left in place), without regard to the irrigation solution. Alternatively, when we removed the wire after 24 hours, irrigated the wound, and then placed a fresh wire back into the wound, sequential surfactant irrigation showed a significant advantage over NS (54% of the animals irrigated with sequential surfactants remained infected versus 100% of the animals irrigated with normal saline). Our findings confirm the importance of a contaminated medical device for promoting foreign body infection; our findings also show that sequential surfactant irrigation has therapeutic value in a rat model of orthopaedic device infection; this irrigation protocol should be studied further as a potential agent for the treatment of infected orthopaedic wounds.

Surfactant wound irrigation for the treatment of staphylococcal clinical isolates.

Deep wound infection involving an implanted biomaterial is a devastating complication in orthopaedic surgery. Two-thirds of such infections are monomicrobial and the most commonly isolated bacteria in human osteomyelitis and orthopaedic device infection are Staphylococcus aureus and Staphylococcus epidermidis. The purpose of the current study was to examine the effectiveness of the previously reported sequential surfactant irrigation protocol against human-isolated clinical strains of Staphylococcus aureus and Staphylococcus epidermidis in the rat model of orthopaedic implant contamination. The infectivity rate of human-isolated clinical strains of Staphylococcus aureus in a contaminated complex orthopaedic wound was reduced effectively by a sequential surfactant irrigation protocol. Also, in this model, the infectivity of Staphylococcus epidermidis was reduced by normal saline irrigation alone when compared with no irrigation. Therefore, the sequential surfactant irrigation protocol may represent an effective method of wound irrigation in monomicrobial Staphylococcus aureus orthopaedic implant contamination, and normal saline irrigation may suffice in cases of monomicrobial Staphylococcus epidermidis contamination. Additional studies are necessary to determine the clinical use of surfactant irrigation.