PATHOGEN SCREENING USING OPTICAL EMISSION SPECTROSCOPY (OES)

Apparatus and methods provide discreet and inexpensive screening for pathogens including Covid-19. A sample of bodily fluid such as saliva is energized to generate a plasma, and the optical emission spectra from the plasma is collected and analyzed used a smart optical monitoring system (SOMS) to determine the presence or increase of a protein indicative of a pathogen. The plasma may be generated with a spark, and light may be collected with a smartphone for remote analysis. In particular, in patients with Covid-19 serum concentrations of acute phase proteins (APPs), such as C-reactive protein (CRP) and ferritin, are increased in the cases that develop more severe disease. In addition, increases in serum of several interleukins (IL), such as IL-6 and IL-10, have been described in Covid-19 patients, and these cytokines are known to be mediators of the APPs response.

FIELD OF THE INVENTION

This invention relates generally to pathogen screening and, in particular, to a system and method that may be used for remote screening for infectious diseases, including COVID-19 and viruses.

BACKGROUND OF THE INVENTION

The Corona Virus (Covid19) epidemic is now affecting almost 200 countries, posing a serious threat for public health. More than 10 million people are affected world wide, resulting in more than a half-million casualties. Reliable laboratory diagnosis of the disease has been one of the foremost priorities for promoting public health interventions.

The reverse transcription polymerase chain reaction (RT-PCR) is currently the reference method for COVID-19 diagnosis[1]. However, it also reported a number of false-positive or -negative cases, especially in the early stages of the novel virus outbreak. Moreover, these types of chemical-reaction-based tests are labor, time and reagent dependent. Presently, in some areas patients have to wait for days and weeks to get test results.

Optical Emission Spectroscopy (OES) provides reagent-free, fast chemical analysis. By comparing spectra from reference sample(s) with test samples, results can be obtained in a few seconds using Smart Optical Monitoring System (SOMS)[2-5]. SOMS is described in U.S. Pat. No. 9,752,988, “In-situ identification and control of microstructures produced by phase transformation of a material,” the entire content of which is incorporated herein by reference.

With SOMS, a microstructure detector and in-situ method are used for real-time determination of the microstructure of a material undergoing alloying or other phase transformation. The method carried out by the detector includes the steps of: (a) detecting light emitted from a plasma plume created during phase transformation of a material; (b) determining at least some of the spectral content of the detected light; and (c) determining an expected microstructure of the transformed material from the determined spectral content. Closed loop control of the phase transformation process can be carried out using feedback from the detector to achieve a desired microstructure.

SUMMARY OF THE INVENTION

This invention resides in apparatus and methods for providing discreet and inexpensive pathogen screening, including screening for the novel coronavirus Covid-19. A method of pathogen screening according to the invention includes the initial step of providing a sample of bodily fluid. In the preferred embodiments the bodily fluid is saliva. The sample is energized to generate a plasma, and the optical emission spectra from the plasma is collected and analyzed used a smart optical monitoring system (SOMS). In particular, spectra from the sample is analyzed to determine the presence or increase of a protein indicative of a pathogen in the body fluid.

The plasma may be generated by creating a spark where sample is positioned. The light from the plasma may be collected with a lens and transmitted to a SOMS system via fiber optics. The SOMS system breaks down the light into individual spectra, which is sent to a computer to analyze and provide the composition information. The light may also be collected using a camera of a smartphone, and transmitting the digitized data to a central station where the SOMS system and computer are located. Such an arrangement enables an individual to perform the test remotely (i.e., at home).

An increase in the presence of proteins in the sample can be used to diagnose patients with diseases including Covid-19. In particular, in patients with Covid-19 serum concentrations of acute phase proteins (APPs), such as C-reactive protein (CRP) and ferritin, are increased in the cases that develop more severe disease. In addition, increases in serum of several interleukins (IL), such as IL-6 and IL-10, have been described in Covid-19 patients, and these cytokines are known to be mediators of the APPs response.

Additionally, other APPs such as ferritin, haptoglobin, serum amyloid A, different interleukins, and other analytes related to the immune response, such as adenosine deaminase (ADA), can be measured in saliva. By comparing these proteins between healthy individuals and those with disease, it is possible to assess the differences, which can result from changes in the circulating levels of proteins and/or from changes in the salivary gland secretion, associated with a disease such as Covid-19.

DETAILED DESCRIPTION OF THE INVENTION

Optical emission spectroscopy (OES) is a method of chemical analysis that uses the intensity of light emitted from plasma formed during material deposition to determine the quantity and quantity of elements in target objects [3-5]. In addition, the OES collection of the emission spectra generated during an additive manufacturing (AM) process can be used to provide more fundamental physical information, such as the composition of the materials. The emission signature, in addition to chemical composition, can also show the genesis of the spectrum, which can be correlated with various characteristics of the object from which plasma signal is generated.

As shown inFIG. 1, plasma may be generated by creating a spark where saliva is positioned. The light from the plasma is collected by a lens and transmitted to a SOMS system via fiber optics. The SOMS system breaks down the light into individual spectra, which is sent to a computer to analyze and provide the composition information. It is possible to collect the light using a camera of a smart phone and transmit the digitized data to a central station where the SOMS system and computer are located. Such an arrangement enables an individual to perform the test remotely (i.e., at home), and send the data to a central station for analysis.

The principle of analysis of the plasma emission is illustrated inFIG. 2. The approach is similar to using a metallic additive manufacturing (AM) process. In AM, metal powders are melted and partially evaporated under the illumination of a highly energetic laser. The metal vapor and shielding gas are excited to high energy level state, with transitions to lower energy level states. In the downward electron transitions, photon wavelengths determined by the energy gaps of the transitions are released and recorded as line-emission spectra. Since the energy gaps are characteristics of elements present, the wavelengths of line emissions in spectra can be used as identifiers for the radiating elements. Further information on emission spectroscopy can be found in [6].

The spectral image inFIG. 2, for instance, is the spectra collected during laser additive manufacturing of a 7075 aluminum alloy. Peaks at wavelengths, 396.15 nm, 382.94 nm, 357.87 nm, are identified as the peaks of Al, Mg, and Cr [7] which are the main elements in the target material.

The intensity of the spectrum is proportional to the density of emitted photons. Under the local thermal equilibrium assumption, the emission density (Iij(λ)) of photons is:

where the partition function U(T) is the statistical occupation fraction of every level k of the atomic species:

There are two types of variables associated with this analysis: 1) element-determined variables, including the wavelength of the photon (λ), the transition probability (Aij), the degeneracy of the upper level (gi); the energy levels of level i (Ei) and level j (Ej); and 2) the plasma-determined variables, including the number of neutral atoms in plasma (n0), the temperature of plasma (T), and the spectral line profile I(λ).

These variables are directly correlated with reference spectra to determine the composition and other properties. For example, the laser power density determines the temperature and electron density of the plasma, which in turn determines the intensity and profile of spectra. Parameters, including laser properties (wavelength, power distribution), powder flow rate, and shielding gas also influence the spectral properties significantly. Therefore, the relationship between spectral signal and manufacturing quality means OES has significant potential for in-situ diagnosis.

Preliminary Results for Protein Identification:

FIGS. 3A, B show the spectra of saliva with and without protein. An increase in the presence of proteins in saliva can be used to diagnose patients with Covid-19. In particular, in patients with Covid-19 serum concentrations of acute phase proteins (APPs), such as C-reactive protein (CRP) and ferritin, are increased in the cases that develop more severe disease. In addition, increases in serum of several interleukins (IL), such as IL-6 and IL-10, have been described in Covid-19 patients, and these cytokines are known to be mediators of the APPs response.

Additionally, other APPs such as ferritin, haptoglobin, serum amyloid A, different interleukins, and other analytes related to the immune response, such as adenosine deaminase (ADA), can be measured in saliva. By comparing these proteins between healthy individuals and those with disease, it is possible to assess the differences, which can result from changes in the circulating levels of proteins and/or from changes in the salivary gland secretion, associated with a disease such as Covid-19.

REFERENCES