The present disclosure relates to a monolayer graphene-based multiplex malaria diagnostic sensor. Specifically, a monolayer graphene-based sensor that is able to simultaneously detect the presence of different Plasmodium species, presence of drug-resistant Plasmodium species, and also the presence of a relevant polymorphism in a subject, in particular G6PD single nucleotide polymorphisms.
The present disclosure also relates to a monolayer graphene-based sensor, method and kit for a rapid diagnosis of malaria using a non-invasive biological sample obtained from a subject, preferably in saliva or urine samples.
Malaria is one of the deadliest infectious diseases in the world which can be prevented through timely diagnosis and treatment. However, current malaria diagnostic tools have limitations. Existent RDTs for malaria are able to detect one species (P. falciparum) or multiple species (P. vivax, P. malariae, P. ovale) but require human interpretation and make use of blood invasive samples, due to its high concentration of parasites. Additionally, prevalence of parasites resistant to artemisinin and other drugs used to treat malaria, is rising at an alarming rate, compromising the treatment. Moreover, millions of people in endemic regions have gene mutations (G6PD) which confers a potential risk of hemolysis by the commonly prescribed antimalarial drugs. Screening of these types of mutations can prevent unnecessary deaths. Therefore, novel diagnostic tools for malaria are urgently needed. The use of a monolayer graphene-based multiplex malaria diagnostic sensor with ability to detect malaria spp, drug resistance and host mutations is thus very beneficial. The test result will make it possible to simultaneously identify the type of malaria parasite as well as its resistance to drugs, enabling a more targeted and efficient treatment with lower risks, and uses non-invasive samples such as saliva.
Document U.S. Ser. No. 10/020,300-B2 discloses arrays may be employed to detect the presence and/or concentration changes of various analyte types in chemical and/or biological processes. Specifically, the system may comprise graphene and may detect DNA hybridization and/or sequencing reactions.
Document U.S. Ser. No. 10/793,898B2 discloses a method, systems, and nano-sensor devices for detecting or discriminating nucleic acids with a single nucleotide resolution based on nucleic acid strand displacement.
Document WO2016164783 discloses a system and method for DNA sequencing and blood chemistry analysis. Specifically, a system comprising a plurality of transistors, wherein at least one transistor comprises graphene, whereby electrical properties of the at least one transistor changes in response to contact with a DNA sequence.
Document CN107051601 discloses nucleic acid detection microfluidic chip based on graphene field effect tube. Specifically, nucleic acid detection microfluidic chip based on graphene field effect tubes.
Document JP2012247189 discloses a graphene sensor for detecting substance species. Specifically, the graphene sensor comprises a DNA fragment having a known base sequence as a functional group.
Document CN109580584 discloses a saliva diagnostic sensor comprising graphene.
These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.
The present disclosure relates to a monolayer graphene-based multiplex malaria diagnostic sensor. Specifically, a monolayer graphene-based sensor that is able to simultaneously detect the presence of different Plasmodium species, presence of drug-resistant Plasmodium species, and also the presence of G6PD single nucleotide polymorphism in the test subject.
The disclosed diagnostic sensor is stable in a wide range of temperature, compatible with non-invasive sampling methods (such as saliva or urine), and returns a result rapidly, preferably in less than one hour. With the retrieved results it is possible to conclude about the presence or absence of Plasmodium species in the biological sample, and also design a suitable treatment based on drug resistance and/or polymorphisms detected.
The advantage of the sensor of the present disclosure is that it can be deployed to various settings, especially malaria rampant settings where it is more often than not impossible to set up the full spectrum of diagnostic laboratory tests required to accurately detect and diagnose malaria. Additionally, the sensor of the present disclosure is especially advantageous for settings where it will be challenging to provide refrigeration for temperature control and to provide phlebotomy expertise to obtain blood samples. Thus, the sensor of the present disclosure is heat resistant and utilizes saliva as a diagnostic sample makes it ideal for mass, rapid, field deployment.
In an embodiment, the present disclosure relates to a monolayer graphene-based sensor for a rapid diagnosis of malaria using a non-invasive biological sample obtained from a subject.
In an embodiment, the sensor comprises the following elements:
The sequences of nucleic acid probes of the present disclosure can be obtained by isolation or synthesis of deoxyribonucleic acid (DNA). Isolated DNA is a DNA that results from an extraction process in which the DNA present in the nucleus of a cell has been separated from other cellular components; DNA synthesis relates to the artificial creation of DNA, that results in synthetic DNA.
In an embodiment, the sensor may further comprise at least 1 isolated/synthetic nucleic acid probe for confirming the human origin of the biological sample (positive control).
In an embodiment, the sensor is able to detect the presence of different Plasmodium species, presence of drug-resistant Plasmodium species and the presence of G6PD single nucleotide polymorphism in a saliva sample or a urine sample.
In an embodiment, the sensor is able to detect the presence of different Plasmodium species, presence of drug-resistant Plasmodium species and the presence of G6PD single nucleotide polymorphisms in less than one hour, preferably less than 45 minutes, more preferably less than 40 minutes.
In an embodiment, the isolated/synthetic nucleic acid probes for functionalizing are selected from deoxyribonucleic acid probes, ribonucleic acid probes, locked nucleic acid probes, or mixtures thereof.
In an embodiment, the sensor comprises at least 3 different isolated/synthetic nucleic acid probes for identifying the presence of at least 3 different Plasmodium species in the biological sample and a human control, wherein the isolated/synthetic nucleic acid probes comprise at least a sequence 90% identical to the sequences of the following list, or mixtures thereof. Preferably 91% identical, 92% identical, 93% identical, 94% identical, 95% identical, 96% identical, 97% identical, 98% identical, 99% identical or identical.
P. falciparum
P. falciparum
P. falciparum
P. falciparum
P. falciparum
P. vivax
P. vivax
P. vivax
P. vivax
P. vivax
P. knowlesi
P. knowlesi
P. knowlesi
P. knowlesi
P. knowlesi
P. ovale
P. ovale
P. ovale
P. ovale
P. ovale
P. malariae
P. malariae
P. malariae
P. malariae
P. malariae
Plasmodium
Plasmodium
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
In an embodiment, the sensor comprises at least 5 different isolated/synthetic nucleic acid probes for identifying the presence of at least 5 different Plasmodium species in the biological sample, wherein the isolated/synthetic nucleic acid probes comprise at least a sequence 90% identical to the sequences of the following list, or mixtures thereof. Preferably 91% identical, 92% identical, 93% identical, 94% identical, 95% identical, 96% identical, 97% identical, 98% identical, 99% identical or identical.
P. falciparum
P. falciparum
P. falciparum
P. falciparum
P. falciparum
P. vivax
P. vivax
P. vivax
P. vivax
P. vivax
P. knowlesi
P. knowlesi
P. knowlesi
P. knowlesi
P. knowlesi
P. ovale
P. ovale
P. ovale
P. ovale
P. ovale
P. malariae
P. malariae
P. malariae
P. malariae
P. malariae
Plasmodium
Plasmodium
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
In an embodiment, the 5 different Plasmodium species in which the sensor is able to detect are Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale, Plasmodium knowlesi.
In an embodiment, the isolated/synthetic nucleic acid probe for detecting the presence of single nucleotide polymorphism is an isolated/synthetic nucleic acid probe for detecting the presence of glucose-6-phosphate dehydrogenase single nucleotide polymorphism.
In an embodiment, the isolated/synthetic nucleic acid probe for detecting the presence of single nucleotide polymorphism comprise at least a sequence 90% identical to the sequences of the following list, or mixtures thereof. Preferably 91% identical, 92% identical, 93% identical, 94% identical, 95% identical, 96% identical, 97% identical, 98% identical, 99% identical or identical.
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
Methods for the alignment of sequences for comparison are well known in the art, such methods include GAP, BESTFIT, BLAST, FASTA and TFASTA. GAP uses the algorithm of Needleman and Wunsch ((1970) J Mol Biol 48: 443-453) to find the global (over the whole the sequence) alignment of two sequences that maximizes the number of matches and minimizes the number of gaps. The BLAST algorithm (Altschul et al. (1990) J Mol Biol 215: 403-10) calculates percent sequence identity and performs a statistical analysis of the similarity between the two sequences. The software for performing BLAST analysis is publicly available through the National Centre for Biotechnology Information (NCBI). Global percentages of similarity and identity may also be determined using one of the methods available in the MatGAT software package (Campanella et al., BMC Bioinformatics. 2003 Jul. 10; 4:29. MatGAT: an application that generates similarity/identity matrices using protein or DNA sequences). Minor manual editing may be performed to optimise alignment between conserved motifs, as would be apparent to a person skilled in the art. The sequence identity values, which are indicated in the present subject matter as a percentage were determined over the entire amino acid sequence, using BLAST with the default parameters.
Another aspect of the present disclosure relates to a kit for diagnosing malaria using a biological sample from a subject comprising the sensor described in any of the previous claims.
Another aspect of the present disclosure relates a method for obtaining the sensor of the present disclosure, comprising the following steps:
In an embodiment the method may further comprise the step of: cleaning a graphene field-effect transistor comprising a graphene monolayer; passivating a gold region of the graphene field-effect transistor.
In an embodiment, the antimalaria drug resistance is resistance to a drug selected following list: chloroquine, mefloquine, doxycycline, atovaquone, proguanil.
The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.
The present disclosure relates to a monolayer graphene-based multiplex malaria diagnostic sensor. Specifically, a monolayer graphene-based sensor that is able to simultaneously detect the presence of different Plasmodium species, presence of drug-resistant Plasmodium species, and also the presence of G6PD single nucleotide polymorphisms in the test subject.
The present disclosure also relates to a monolayer graphene-based sensor, method, and kit for a rapid diagnosis of malaria using a non-invasive biological sample obtained from a subject, preferably in saliva or urine samples.
In an embodiment, the multiplex chip was obtained using a method comprising 7 lithography steps. The method was optimized to ensure that the chip comprise suitable full-coverage nitride passivation leaving open only the graphene sensor, similar to that described in previous works. In this optimization, a process for passivation of silicon nitride passivation of the graphene was developed, where a sacrificial nickel or copper thin film followed by aluminium is lithographically sputtered onto transferred silicon to protect graphene from the rest of the processes including deposition of the passivation, lithography, reactive ion etching, and wet etch of the sacrificial layer. The passivation covers source and drain electrodes, leaving only the graphene channel exposed. The process is described in P. D. Cabral et al, Clean-Room Lithographical Processes for the Fabrication of Graphene Biosensors. This passivation results in increased yield and uniformity of the sensor properties across the wafer.
In an embodiment, the method of obtaining the multiplex sensor comprises the following steps:
In an embodiment, each sensor or group of sensors is modified with suitable synthetic nucleic acid probes for multiplex detection. For tests with synthetic DNA target, 10 μL are placed on the suitable region of the chip. DNA target prepared in the 10 mM PB with 50 mM magnesium chloride and 150 mM sodium chloride pH 7, from the lowest to the highest concentration for 40 min each and rinse with PB for 5 s. In another embodiment, for real samples testing place 10 μL on the suitable region of the chip wait 40 min and rinse with PB for 5 s.
In an embodiment, the sensors obtained were characterized at the wafer level. It was observed that a large majority of the sensors exhibit good electrical properties, as measured by the zero-gate electrical channel resistance.
In an embodiment, the sequences of the probes used to functionalize the sensors are selected from the following list:
Malaria
P. falciparum
Plasmodium
Malaria
P. falciparum
Plasmodium
Malaria
P. falciparum
Plasmodium
Malaria
P. vivax
Plasmodium
Malaria
P. vivax
Plasmodium
Malaria
P. vivax
Plasmodium
Malaria
P. knowlesi
Plasmodium
Malaria
P. knowlesi
Plasmodium
Malaria
P. knowlesi
Plasmodium
Malaria
P. ovale
Plasmodium
Malaria
P. ovale
Plasmodium
Malaria
P. ovale
Plasmodium
Malaria
P. malariae
Plasmodium
Malaria
P. malariae
Plasmodium
Malaria
P. malariae
Plasmodium
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
Homo sapiens
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
P falciparum
Homo sapiens
Homo1
Homo sapiens
Homo2
Malaria
Plasmodium
Plasmodium
Plasmodium
Malaria
P. Falciparum
P.
Plasmodium
Falciparum
Malaria
P. Falciparum
P.
Plasmodium
Falciparum
Malaria
P. Vivax
P. Vivax
Plasmodium
Malaria
P. Vivax
P. Vivax
Plasmodium
Malaria
P. Malariae
P.
Plasmodium
Malariae1
Malaria
P. Malariae
P.
Plasmodium
Malariae2
Malaria
Plasmodium
Plasmodium
Plasmodium
Malaria
P. Ovale
P. Ovale1
Plasmodium
Malaria
P. Ovale
P. Ovale2
Plasmodium
Malaria
P. Knowlesi
P.
Plasmodium
Knowlesi1
Malaria
P. Knowlesi
P.
Plasmodium
Knowlesi2
In an embodiment, the sensors obtained were characterized using spiked buffer.
In an embodiment, the sensors were functionalized according to the procedure published in the paper by E. Fernandes et al. 2019 “Functionalization of single-layer graphene for immunoassays”. A sensor comprising 7 separate sensor groups for multiplex diagnosis was functionalized with 7 distinct deoxyribonucleic acid (DNA) probes. Each of the sensor groups was then calibrated with increasing concentrations of the corresponding DNA perfect match diluted in phosphate buffer (PB).
The sensors showed consistent response starting in the attomolar range.
In an embodiment, sensors that were functionalized with DNA and locked nucleic acid (LNA) probes showed similar responses as sensors functionalized with only DNA.
In an embodiment, the effectiveness of the functionalized sensors was tested using saliva and artificial DNA.
In an embodiment, the effectiveness of the functionalized sensors against complex matrices such as saliva were tested by using commercial saliva samples spiked with 1 μM of synthetic DNA sequence of Plasmodium falciparum fully complementary to sequence immobilized on the graphene surface.
In an embodiment, the results show that the different saliva tested all show the same tendency, with shifts in signal enabling detection. Results were similar when the test was conducted using saliva samples collected from test individuals and pre-treated with an extraction kit or charcoal stripped.
The results show that the different saliva samples collected from individuals in different age groups exhibit marked differences in signal level as compared to saliva samples from commercial providers corresponding to different age groups (3-10, adult).
In an embodiment, quantification of protein contents, ssDNA and dsDNA was performed for each saliva sample type. There was no clear correlation between saliva sample type and level of signal obtained.
In an embodiment, the effectiveness of the functionalized sensors was further tested using saliva and natural DNA extracted from parasite culture. Parasites P. falciparum subtype Dd2 were cultured and its DNA was extracted using molecular biology techniques. A solution containing 2000 copies/μL of parasites DNA was used for testing. Sequential dilutions were performed to obtain concentrations in the range of 1 aM to 1 μM. The sensors were previously functionalized with a synthetic DNA probe for P. falciparum parasite. The extracted parasite DNA was mixed with PB, saliva or saliva diluted 20× with PB. The results of the test were shown in
In an embodiment, the shelf-life and heat resistance capacity of the functionalized sensors were determined.
In an embodiment, the functionalized sensors were placed in the following conditions: 20° C., 45° C. at 75% relative humidity, 65° C. dry, 65° C. at 75% relative humidity. Thereafter, the sensors were tested after 1 week and after 2 weeks.
The sensors functionalized with DNA and LNA were shown to be working after heat treatment, often with improved effectiveness.
Each sensing region of the multiplex chips was functionalized overnight at 4° C. with 10 μL of specific probes for the different Plasmodium species, drug-resistant Plasmodium species, and G6PD single nucleotide polymorphism.
Each sensing region was rinsed for 5 sec with PB and most of the solution was removed without allowing full dryness. Then, 20 μL of 100 mM Ethanolamine prepared in PB pH 8.5 were placed on the chip for 30 min and rinsed with PB for 5 s. The chips were ready to use for sample analysis.
For the analysis, 10 μL of the saliva patient were added to each sensing region of the multiplex chips for 40 min, followed by PB rinsing for 5 s. If necessary, saliva can be diluted 20-fold in buffer.
The following cases might follow:
If the results are positive for a combination of multiple Plasmodium species with and without drug-resistance sensitivity, the drugs are immediately adjusted to the patient condition.
Independently of the type of infection, if patients are positive for G6PD gene the patient cannot be treated with Primaquine and Tafenoquineis due to the adverse effects (hemolysis) and possible death.
Currently, the rapid diagnosis of multiple infections is possible, however infections resistance and host mutation (G6PD single nucleotide polymorphism) assessment require laboratory equipment which take at least 24 h to provide results.
The present disclosure determines the diagnosis of multiple infectious with additional information of drug-resistance and G6PD single nucleotide polymorphism through a non-invasive saliva sample within less than 40 min. This detailed information assists the medical teams on suitable treatments increasing treatment success rates.
The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof.
The embodiments described above are combinable.
This disclosure was funded by the Project MULTIMAL, ATTRACT ID 1176, funded by European Union's Horizon 2020 research and innovation programme under grant agreement No. 777222.
Number | Date | Country | Kind |
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117090 | Feb 2021 | PT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IB22/51743 | 2/28/2022 | WO |