Influence of AC electric field on the charge generation in albumin solution in a flow-based AFM-fishing system

The work was supported by the Russian Ministry of Education and Science, Agreement No. 14.613.21.0063, universal identifier RFMEFI61317X0063

Use of Microwave Radiometry to Monitor Thermal Denaturation of Albumin

This study monitored thermal denaturation of albumin using microwave radiometry. Brightness Temperature, derived from Microwave Emission (BTME) of an aqueous solution of bovine serum albumin (0.1 mM) was monitored in the microwave frequency range 3.8–4.2 GHz during denaturation of this protein at a temperature of 56°C in a conical polypropylene cuvette. This method does not require fluorescent or radioactive labels. A microwave emission change of 1.5–2°C in the BTME of aqueous albumin solution was found during its denaturation, without a corresponding change in the water temperature. Radio thermometry makes it possible to monitor protein denaturation kinetics, and the resulting rate constant for albumin denaturation was 0.2 ± 0.1 min−1, which corresponds well to rate constants obtained by other methods

Лапароскопические операции при остром аппендиците, осложненном перитонитом

Introduction. Acute appendicitis (AA) is one of the most common acute abdominal surgical diseases. The current incidence, according to various authors, is 22.8 per 10,000 inhabitants. Annually, 50 to 70 thousand people die from AA and its complications around the world. Laparoscopy is generally accepted as the most effective method of differential diagnosis of AA. It is fundamentally significant to move from the diagnostic stage to the therapeutic one, i.e. to perform the elimination of the disease, including cases with other surgery-requiring pathology detected. Aim. To evaluate the role of video-endoscopic surgical methods in the surgical management of acute appendicitis complicated by peritonitis. Materials and methods. The analysis of recent publications and personal clinical experience revealed that diagnostic laparoscopy, unless contraindicated, should be performed as the initial step in suspected acute abdominal pathology. When the surgery is technically performable, laparoscopy also causes curative effect. Results and discussion. The use of laparoscopy in surgical treatment of acute appendicitis complicated by peritonitis has proven advantages for the patient over open surgery. An adequate appendectomy as a reliable method for elimination of the source of peritonitis is the key to successful treatment of patients. Laparoscopic lavage in the early postoperative period against the postoperative peritonitis with developing complications, is considered to be an alternative method to non-surgical treatment or delayed intervention and to have better ultimate results than percutaneous drainage or relaparotomy. Conclusion. The success of video-endoscopic technologies application depends not only on the technical aspects, but also on the correct choice of indications for such an intervention and their appropriate combination with open surgeries.Введение. Острый аппендицит (ОА) — одно из самых широко распространенных острых хирургических заболеваний брюшной полости. В настоящее время, по данным различных авторов, частота встречаемости составляет 22,8 на 10 000 населения. Ежегодно в мире от ОА и его осложнений умирает от 50 до 70 тыс. человек. Общепризнанным является мнение, что лапароскопия — это наиболее эффективный метод дифференциальной диагностики ОА. Принципиальным фактом является возможность перехода от диагностического этапа к лечебному, т. е. выполнению устранения заболевания, в том числе при выявлении другой патологии, требующей хирургической коррекции. Цель исследования: оценить роль эндовидеохирургических методов в хирургическом лечении острого аппендицита, осложненного перитонитом. Материалы и методы. Анализ современной литературы и собственный клинический опыт позволяют утверждать, что в отсутствие противопоказаний диагностическая лапароскопия должна выполняться первичным этапом при подозрении на острую абдоминальную патологию. Она же становится лечебной при наличии технических возможностей выполнения операции. Результаты и обсуждение. Применение лапароскопических методов в хирургическом лечении острого аппендицита, осложненного перитонитом, имеет доказанные преимущества для пациента перед открытой операцией. Залогом успешного лечения пациентов является надежная ликвидация источника перитонита — выполнение адекватной аппендэктомии. Лапароскопическая санация в раннем послеоперационном периоде на фоне послеоперационного перитонита, при развивающихся осложнениях, является альтернативным методом безоперационному лечению и отложенному вмешательству и, в конечном счете, имеет лучшие результаты чем, чрескожное дренирование или релапаротомия. Заключение. Успех применения видеоэндоскопических технологий зависит не только от технических аспектов, но и от верного выбора показаний к такой операции и рациональному использованию их сочетания с открытыми операциями.

Spontaneous Charge Generation in Flowing Albumin Solutions at 35 °C and 38 °C

The time dependence of a charge accumulation in a 10−15 M albumin solution, flowing through a measuring cell of an analytical flow system injector, had a nonlinear character under certain conditions, within a human physiological temperature range. Sharp charge increases depended on albumin concentration. This effect must be taken into consideration when generating models that describe electrokinetic phenomena in flowing protein solutions and when developing analytical flow systems for the registration of biomolecules in low concentration ranges

Influence of Chip Materials on Charge Generation in Flowing Solution in Nanobiosensors

Nowadays, nanobiosensors are being intensively developed due to the potential possibilities of their use for early diagnosis of diseases. This interest is enhanced by the fact that, as is known, a pathological process at an early stage is characterized by the appearance of marker proteins at very low (10−15 M and lower) concentrations in blood. Highly-sensitive nanobiosensor systems (including those based on an atomic force microscope, AFM) allows one to detect proteins at such low concentrations. The influence of the charge generated in the analyte solution flowing through the biosensor injector into the measuring cell during measurements is considered to be an important factor conditioning such a high detection sensitivity. In the present study, it was demonstrated that the presence of an AFM chip (made of mica and graphite) near the nozzle of the injector supplying an analyte solution into the measuring cell of the AFM-based fishing system (AFM-based nanobiosensors) causes an increase in charge generation upon the injection of the solution. Moreover, the influence of polymer materials (which are widely used in nanobiosensors) and communications on charge generation in the flow-based section of AFM-based nanobiosensors was studied. A stimulating influence of a low (femtomolar) concentration of proteins on the charge generation in polymeric injectors of flow-based nanobiosensors was demonstrated. Besides, a stimulating influence of an external low-frequency AC electric field on the charge generation in the nanobiosensor injector was found. Measurements were carried out in the temperature range corresponding to the physiological temperature (35 °C)

Influence of a Pulsed Electric Field on Charge Generation in a Flowing Protein Solution

It is known that a charge is generated in water and protein solutions upon their motion; this phenomenon is also observed in analytical systems for atomic force microscopy (AFM)-based fishing. At that, the efficiency of protein fishing correlates with the value of charge, generated upon the motion of the analyzed solution. Earlier, we demonstrated that a pulsed electric field can well be used for the enhancement of the efficiency of AFM-based fishing of low-abundant protein. In this paper, we have demonstrated the influence of a pulsed electric field on the stimulation of the electric charge generation in a solution of low-abundant proteins observed in the injector part of an AFM-based fishing system at 23 °C and 38 °C. Taking this effect into account is important for the development of novel highly sensitive flow-based diagnostic systems, as well as for the development of models describing the influence of a pulsed electric field on pathological processes in the body, hemodynamics, and physicochemical properties of solutions

The Use of Excess Electric Charge for Highly Sensitive Protein Detection: Proof of Concept

In highly sensitive bioanalytical systems intended for the detection of protein biomarkers at low and ultra-low concentrations, the efficiency of capturing target biomolecules from the volume of the analyzed sample onto the sensitive surface of the detection system is a crucial factor. Herein, the application of excess electric charge for the enhancement of transport of target biomolecules towards the sensitive surface of a detection system is considered. In our experiments, we demonstrate that an uncompensated electric charge is induced in droplets of protein-free water owing to the separation of charge in a part of the Kelvin dropper either with or without the use of an external electric field. The distribution of an excess electric charge within a protein-free water droplet is calculated. It is proposed that the efficiency of protein capturing onto the sensitive surface correlates with the sign and the amount of charge induced per every single protein biomolecule. The effect described herein can allow one to make the protein capturing controllable, enhancing the protein capturing in the desired (though small) sensitive area of a detector. This can be very useful in novel systems intended for highly sensitive detection of proteins at ultra-low (≤10−15 M) concentrations

Highly Sensitive Detection of CA 125 Protein with the Use of an n-Type Nanowire Biosensor

The detection of CA 125 protein in a solution using a silicon-on-insulator (SOI)-nanowire biosensor with n-type chip has been experimentally demonstrated. The surface of nanowires was modified by covalent immobilization of antibodies against CA 125 in order to provide the biospecificity of the target protein detection. We have demonstrated that the biosensor signal, which results from the biospecific interaction between CA 125 and the covalently immobilized antibodies, increases with the increase in the protein concentration. At that, the minimum concentration, at which the target protein was detectable with the SOI-nanowire biosensor, amounted to 1.5 × 10−16 M

Ultrasensitive Detection of 2,4-Dinitrophenol Using Nanowire Biosensor

The method for the detection of 2,4-dinitrophenol (DNP) in solution is proposed. This method employs the sensors based on silicon nanowire field-effect transistors with protective layers of high-k dielectrics, whose surface is functionalized with an amino silane. Direct highly sensitive detection of DNP has been demonstrated, and the lowest detectable concentration of DNP was determined to be 10−14 M. Silicon-on-insulator nanowire (SOI-NW) sensors can well be employed for the rapid detection of a wide range of toxic and explosive compounds by selection of sensor surface modification techniques