Fabrication Of Nano-materials Functionalized Microneedle Sensor And Its Application In Real-time Monitoring H₂O₂ Released From Cell And PH Change In Vivo

With the continuous development of biomedicine,the detection technologies used in clinical laboratories are becoming more and more diverse.Among these technologies,biosensor has been widely used in the field of basic medical research and clinical diagnosis because of its advantages such as simple operation,high sensitivity,good specificity,and rapid analysis.Providing a new type of detection platform,biosensors have gradually become a new research hotspot in medicine,which has attracted the attention of many medical researchers.Nanomaterials play a very important role in the preparation of biosensors because of their good adsorptive capacity,large specific surface area,many surface active sites and high catalytic efficiency.The sensitivity and other properties of biosensors have promoted the development of new biosensors and have been widely used in biomolecular detection,disease diagnosis and life sciences.The non-invasive and highly sensitive detection of biomolecules in vivo has been a relentless pursuit of researchers,and microelectrode sensors have a wide range of applications in biomedical applications due to their small size and ease of penetration into the body.Due to the characteristics of micro-portability,low cost,and minimal invasiveness of acupuncture needles,we used an acupuncture needle as the electrode substrate to prepare a microneedle sensor in this experiment,providing a new method for the real-time detection of biomolecules in vivo.In this work,an electrochemical biosensor with functionalized molybdenum disulfide nanomaterials was constructed to achieve sensitive detection of bioactive molecules in vivo.That is,an electrochemical deposition method was used to decorate molybdenum disulfide?MoS₂?on the tip surface of acupuncture needle to prepare a microneedle sensor for real-time monitoring of H₂O₂ released from cells and real-time monitoring of p H change in cerebrospinal fluid of a rat brain.The main contents of this research are mainly focused on the following two parts:Part I:MoS₂/Pt nanocomposite-functionalized microneedle for real-time monitoring of H₂O₂ release from living cells.The content of H₂O₂ is closely related to the occurrence and development of diseases.When excessive H₂O₂ is produced in the body,it can lead to the occurrence of various diseases,such as cancer,diabetes,cardiovascular and neurodegenerative diseases.Therefore,it is of great significance to accurately and rapidly monitor H₂O₂ released from cells,which is conducive to elucidate its mechanism of action in cell physiology and further explore its potential in clinical applications.The MoS₂/PtNPs functionalized microneedle sensor prepared in this work will provide a new technique for detection and diagnosis of H₂O₂-related diseases.We used an acupuncture needle as the electrode substrate and an electrochemical deposition was successively employed to decorate the needle with MoS₂ and Pt NPs,respectively,as the sensing interface to fabricate a MoS₂/PtNPs functionalized microneedle sensor.Scanning electron microscope images were used to characterize the surface morphology of the electrode decorated with nanomaterials step by step,and the electrochemical performance of the modified electrode was examined using electrochemical cyclicvoltammetry?CV?.Theexperimentalresultsshowedthat MoS₂/PtNPs-functionalized microneedle had obvious advantages,compared with bare electrode or MoS₂,PtNPs single-component modified electrode for H₂O₂ catalytic reduction,which benefits from the synergistic effects of MoS₂and Pt NPs.The MoS₂/PtNPs/AN exhibited good selectivity and excellent stability for the detection of H₂O₂.The prepared MoS₂/PtNPs sensors were quantitatively analyzed for different concentrations of H₂O₂ solution.The results showed that within the range of 1 to 100?mol/L,the reduction current of H₂O₂ showed a good linear relationship with the concentration of H₂O₂.The detection limit was calculated to be 0.83?mol/L with high sensitivity.Then,the MoS₂/PtNPs/AN sensors were used to monitor extracellular H₂O₂ release from HeLa cells.When PMA stimulant was added to Hela cells,a remarkable increase of the current signal was observed.It is proved that the Mo S₂/PtNPs nanomaterials-functionalized microneedle sensor could achieve the detection of H₂O₂ release from cell in a real-time manner.Part II:Monitoring of pH change in live rats brain with PAN/MoS₂functionalized microneedleThe concentration of hydrogen ions?H⁺?in body reflects changes in pH.Acid-based disorders usually lead to many cardiovascular and neurological diseases,so it is of great significance to real-time monitor the pathological process of acid-based poisoning in body.A microneedle sensors are constructed for directly detecting pH changes in vivo,having a certain development prospect in the practical application of clinical medicine.In this experiment,acupuncture needles were also used as electrode substrates,and MoS₂ nanosheets and polyaniline?PAN?were respectively modified onto the tip of the needle?AN?by electrochemical polymerization to prepare H⁺-sensitive microneedle sensors.Scanning electron microscopy was used to characterize the surface morphology of different modified electrodes.Open-circuit potentials were measured in phosphate buffer and serum solutions,respectively,with different pH values.The potential signals decreased when the value of p H were increased,ranging from pH 3 to 9,showing a good linear relationship.And the microsensor had a high sensitivity with a pH Nernst response of 50.8 mV/pH.After the microsensor was inserted into the rat brain,several microliters of alkaline Na₂CO₃ solution or acidic NaH₂PO₄ solution were pumped into the vicinity of the PAN/MoS₂/AN electrode to change H⁺concentration in the local environment of the cerebrospinal fluid.By observing change of corresponding open-circuit potentials pH changes in the brain were monitoring in real time.This work demonstrates that the microneedle sensor can achieve real-time pH detection in vivo.