The pen was gilded: special ink will detect an antibiotic-resistant infection in minutes.

Russian scientists have developed plasmonic ink with gold nanoparticles, which can be used to identify a biomarker of Pseudomonas aeruginosa, a dangerous pathogen of nosocomial infections, in a matter of minutes. With the traditional method, diagnosis can take several days. During this time, the bacteria can cause serious harm to the patient's body. The new technology does not require complex sample preparation: it is enough to process the sample with ink and examine it using a portable spectrometer. According to experts, the rapid detection of Pseudomonas aeruginosa is especially important because of its resistance to many antibiotics.

Gold ink

Scientists at MIPT and Moscow State University have developed ink based on gold nanoparticles for instant diagnosis of the causative agent of severe nosocomial infections — Pseudomonas aeruginosa. They can detect dangerous bacteria even in the early stages of the disease in a matter of minutes and do not require sophisticated equipment.

— Now you don't have to wait a few days for bacteria to grow in a Petri dish, send samples to the laboratory and carry out complex sample preparation. It is enough to take a swab with a cotton swab, apply plasmon ink to it and bring a portable spectrometer — the result will be ready in minutes," said a junior researcher at the Faculty of Chemistry of Lomonosov Moscow State University. Evgenia Afonyushkina.

Pseudomonas aeruginosa is one of the dangerous pathogens of nosocomial infections. It can cause severe pneumonia, sepsis, and damage to internal organs, including fatal ones. One of the main obstacles in the fight against the bacterium is its high resistance to many antibiotics. Every year fewer and fewer drugs remain effective against this pathogen.

Sphere of radiance: glowing biochips will detect diseases in the traces of molecules

The technology will detect oncological, cardiovascular and infectious pathologies at an early stage.

The standard diagnosis requires inoculation on nutrient media and incubation for 2-3 days. However, a patient with an acute infection needs treatment immediately, so doctors are forced to prescribe antibiotics "blindly" until results are obtained. This inevitably leads to the unjustified use of heavy drugs, an increase in drug resistance and worsens the prognosis for the patient.

A new development by MIPT and MSU scientists makes it possible to reduce the diagnostic time from several days to several minutes. It is based on the detection of pyocyanin, a characteristic pigment secreted by Pseudomonas aeruginosa.

However, with a small number of bacteria, the pyocyanin signal turns out to be too weak for reliable detection. To solve this problem, scientists have developed an ink based on gold nanostars — particles with sharp spikes. This shape provides a high concentration of electromagnetic field, which amplifies the signal of molecules located near nanostars by millions of times.

Combating nosocomial infections

The ink was placed in a regular pen rod. To carry out the diagnosis, it is enough either to apply ink directly to the sample (for example, to a smear of the patient's saliva), or to pre-create a touch surface on paper, and then apply a sample to it, and then measure the signal with a portable spectrometer.

The whole process takes several minutes and does not require any centrifugation, special reagents, or sterile boxes. The scientists tested plasmonic ink in the laboratory and in the field.

Stem tags: laser taught to "hit" the most tenacious tumor cells

Photodynamic therapy has shown high efficacy against sources of cancer recurrence

— We compared the diagnostic capabilities of laboratory and portable spectrometers. The first one shows extreme sensitivity under ideal conditions, which is important for further fundamental biomedical research based on the proposed pyocyanin detection method. The second is a mobile device that works on the principle of "took a swab, brought it up, got the result," without complicated calibration and configuration. The difference in sensitivity was three orders of magnitude, but even this was enough to detect the biomarker signal in clinically significant concentrations using a portable device," said Ilya Zavidovsky, senior researcher at the Center for Photonics and Two—Dimensional Materials at MIPT.

Clinically significant concentrations of pyocyanin in patients with Pseudomonas aeruginosa infection range from 47 to 100 micromoles per liter. The developed method completely covers this range, which makes it possible to identify the pathogen already at the early stages of the disease.

— Our approach opens up the possibility of conducting analysis without lengthy sample preparation — in fact, in the form in which the material was received from the patient. This allows the method to be applied not only in the laboratory, but also directly at the patient's bedside, in the emergency department or in the emergency room. We have created a simple and affordable tool for quick decision—making about therapy," said Irina Veselova, Head of the Laboratory of Bioanalytical Methods and Optical Sensor Systems at the Moscow State University Faculty of Chemistry.

Scientists have already produced demonstration samples that have proven their effectiveness during experiments. In the near future, we plan to adapt the technology to diagnose whole bacterial cells, as well as other pathogenic microorganisms.

Most often, doctors identify Pseudomonas aeruginosa by clinical manifestations, but there are cases when diagnosis is necessary, says Maria Vedunova, director of the Institute of Biology and Biomedicine at UNN.

— Microorganisms can multiply at a high rate, so diagnosis should be fast. Now, in non-obvious cases, the doctor has to rely on intuition or use additional medications. If he has an express diagnosis at his disposal, it can save the patient's life. Since any additional load is harmful to the body," she said.

According to immunologist Mikhail Bolkov, Pseudomonas aeruginosa is a dangerous nosocomial infection, so the methods of its rapid diagnosis will be in demand by doctors.

Thus, the development can become the basis for creating simple rapid diagnostic systems that will allow doctors to quickly identify the cause of infection and choose treatment tactics. However, before the technology can enter widespread clinical practice, scientists will have to adapt it to identify bacterial cells themselves and confirm the effectiveness of the method when working with patient samples.