Label-free and self-assembled fluorescent DNA nanopompom for determination of miRNA-21.

A label-free fluorescence method based on self-assembled DNA nanopompom has been developed for miRNA-21 detection. In the presence of miRNA-21, three DNA hairpin probes with split G-quadruplex assemble the DNA nanopompom. Based on the isothermal toehold-mediated DNA strand displacement reaction, the target miRNA can be catalytically recycled and trigger three DNA hairpin probes to self-assemble the DNA nanopompom and release the G-quadruplex. The formation of the G-quadruplex increases the fluorescence emission intensity of thioflavin. For thioflavin-based miRNA-21 detection, the excitation and emission wavelengths are set to 425 nm and 490 nm, respectively. The limit of detection for miRNA-21 is 0.8 pM according to F/F0 = 0.0031 × CmiRNA-21 + 1.0382 (R2 = 0.9978). This sensing system provides a low-cost, effective, and convenient method for miRNA detection, which holds great potential in biochemical diagnosis and clinical practice. Graphical abstract Label-free and self-assembled fluorescent DNA nanopompom for miRNA detection.

Correction: An, F., et al. A Conjugate of Pentamethine Cyanine and 18F as a Positron Emission Tomography/Near-Infrared Fluorescence Probe for Multimodality Tumor Imaging. Int. J. Mol. Sci. 2017, 18, 1214.

The authors wish to make the following corrections to this paper [...].

A Conjugate of Pentamethine Cyanine and 18F as a Positron Emission Tomography/Near-Infrared Fluorescence Probe for Multimodality Tumor Imaging.

The novel synthesis of a dual-modality, pentamethine cyanine (Cy5) fluorescent, 18F positron emission tomography (PET) imaging probe is reported. The probe shows a large extinction coefficient and large quantum yield in the biologically transparent, near-infrared window (650-900 nm) for in vivo fluorescent imaging. This fluorophore bears the isotope, 18F, giving a 18F-PET/near-infrared fluorescent (NIRF), bi-modal imaging probe, that combines the long-term stability of NIRF and the unlimited penetration depth of PET imaging. The bi-modal probe is labeled with 18F in a quick, one-step reaction, which is important in working with the rapid decay of 18F. The bi-modal probe bears a free carboxyl group, highlighting a PET/NIRF synthon that can be conjugated onto many advanced biomolecules for biomarker-specific in vivo dual-modal PET/NIR tumor imaging, confocal histology, and utility in multi-fluorophore, fluorescence-guided surgery. Its potential in vivo biocompatibility is explored in a quick proof-of-principal in vivo study. The dye is delivered to A549 xenograft flank-tumors to generate PET and NIRF signals at the tumor site. The tumor distribution is confirmed in ex vivo gamma counting and imaging. Pentamethine cyanine (Cy5) has the ability to preferentially accumulate in tumor xenografts. We substitute the PET/NIRF probe for Cy5, and explore this phenomenon.

Investigation of newly identified G-quadruplexes and their application to DNA detection.

G-quadruplexes are guanine-rich nucleic acid sequences that can act as universal signal-transducers and generate colorimetric, fluorescence, and chemiluminescence signals when complexed with different ligands. Due to their merits including easy modification and low cost, it is of great importance to explore new G-quadruplexes with improved performance. Herein the properties of newly identified G-quadruplexes 9th-3-35 and 10th-2-40 were investigated in detail with UV-vis spectra, circular dichroism (CD) spectra and fluorescence spectra. The results indicated that 9th-3-35 and 10th-2-40 exhibited excellent peroxidase-like activity, as well as fluorescence enhancement of thioflavin T (ThT). Furthermore, the application of G-quadruplexes to DNA detection was performed on account of the ThT fluorescence enhancement, and the limit of detection was as low as 8 pM. This study implied that 9th-3-35 and 10th-2-40 are competitive candidates as signal-transducers in the design of bioassays.

Evaluation of medicine effects on the interaction of myoglobin and its aptamer or antibody using atomic force microscopy.

The effects of medicine on the biomolecular interaction have been given increasing attention in biochemistry and affinity-based analytics since the environment in vivo is complex especially for the patients. Herein, myoglobin, a biomarker of acute myocardial infarction, was used as a model, and the medicine effects on the interactions of myoglobin/aptamer and myoglobin/antibody were systematically investigated using atomic force microscopy (AFM) for the first time. The results showed that the average binding force and the binding probability of myoglobin/aptamer almost remained unchanged after myoglobin-modified gold substrate was incubated with promazine, amoxicillin, aspirin, and sodium penicillin, respectively. These parameters were changed for myoglobin/antibody after the myoglobin-modified gold substrate was treated with these medicines. For promazine and amoxicillin, they resulted in the change of binding force distribution of myoglobin/antibody (i.e., from unimodal distribution to bimodal distribution) and the increase of binding probability; for aspirin, it only resulted in the change of the binding force distribution, and for sodium penicillin, it resulted in the increase of the average binding force and the binding probability. These results may be attributed to the different interaction modes and binding sites between myoglobin/aptamer and myoglobin/antibody, the different structures between aptamer and antibody, and the effects of medicines on the conformations of myoglobin. These findings could enrich our understanding of medicine effects on the interactions of aptamer and antibody to their target proteins. Moreover, this work will lay a good foundation for better research and extensive applications of biomolecular interaction, especially in the design of biosensors in complex systems.

Copper-Based Single-Atom Nanozyme System Mimicking Platelet Cells for Enhancing the Outcome of Radioimmunotherapy.

Background: Radiotherapy is an indispensable part of the multidisciplinary treatment of breast cancer (BC). Due to the potential for serious side effects from ionizing radiation in the treatment of breast cancer, which can adversely affect the patient's quality of life, the radiation dose is often limited. This limitation can result in an incomplete eradication of tumors. Methods: In this study, biomimetic copper single-atom catalysts (platelet cell membrane camouflaging, PC) were synthesized with the aim of improving the therapeutic outcomes of radiotherapy for BC. Following guidance to the tumor site facilitated by the platelet cell membrane coating, PC releases a copper single-atom nanozyme (SAzyme). This SAzyme enhances therapeutic effects by generating reactive oxygen species from H2O2 and concurrently inhibiting the self-repair mechanisms of cancer cells through the consumption of intracellular glutathione (GSH) within the tumor microenvironment. PC-augmented radiotherapy induces immunogenic cell death, which triggers an immune response to eradicate tumors. Results: With the excellent biocompatibility, PC exhibited precise tumor-targeting capabilities. Furthermore, when employed in conjunction with radiotherapy, PC showed impressive tumor elimination results through immunological activation. Remarkably, the tumor suppression rate achieved with PC-enhanced radiotherapy reached an impressive 93.6%. Conclusion: Therefore, PC presents an innovative approach for designing radiosensitizers with tumor-specific targeting capabilities, aiming to enhance the therapeutic impact of radiotherapy on BC.

Huge gastric plexiform fibromyxoma presenting as pyemia by rupture of tumor: A case report.

BACKGROUND: Plexiform fibromyxoma (PF) is a rare mesenchymal tumor, with limited case reports worldwide. Common clinical symptoms are abdominal discomfort and bleeding signs, which frequently present slow-onset in reported cases. Herein, we report a case of gastric PF presenting as acute onset and with pyemia accom-panying tumor rupture. We resected the tumor as well as the distal gastric, bulbus duodeni and gallbladder for treatment in emergency surgery. Notably, before the onset of the disease, the patient received coronavirus disease 2019 (COVID-19) vaccines. CASE SUMMARY: A 26-year-old man was admitted to our hospital, due to abdominal pain and fever after having received COVID-19 vaccines. Laboratory examination indicated severe sepsis. Computed tomography scan revealed a large mass in the abdomen. Deformation of the gastrointestinal tract was seen during gastroscopy. After failure of anti-infective treatment and symptoms of shock developed, he received an emergency surgery. We found a huge and partly ruptured mass, with thick purulence. Microscopically, the mass was composed of spindle cells with clarified cytoplasm, accompanied by myxoid stroma and arborizing blood vessels. Immunohistochemistry showed the tumor cells as positive for smooth muscle actin and succinate dehydrogenase subunit B but negative for DOG-1 and CD117. Finally, the patient was diagnosed with gastric PF and discharged from the hospital. CONCLUSION: Gastric PF manifesting as tumor rupture combined with pyemia is rare. Timely surgery is critical for optimal prognosis.

Correction: Facile synthesis of near-infrared bodipy by donor engineering for in vivo tumor targeted dual-modal imaging.

Correction for 'Facile synthesis of near-infrared bodipy by donor engineering for in vivo tumor targeted dual-modal imaging' by Feifei An et al., J. Mater. Chem. B, 2021, 9, 9308-9315, DOI: 10.1039/D1TB01883C.

m6 A demethylase ALKBH5 drives denervation-induced muscle atrophy by targeting HDAC4 to activate FoxO3 signalling.

BACKGROUND: Skeletal muscle atrophy is a common clinical manifestation of various neurotrauma and neurological diseases. In addition to the treatment of primary neuropathies, it is a clinical condition that should be investigated. FoxO3 activation is an indispensable mechanism in denervation-induced muscle atrophy; however, upstream factors that control FoxO3 expression and activity have not been fully elucidated. N6 -methyladenosine (m6 A) methylation is a novel mode of epitranscriptional gene regulation that affects several cellular processes. However, the biological significance of m6 A modification in FoxO3-dependent atrophy is unknown. METHODS: We performed gain-of-function and loss-of-function experiments and used denervation-induced muscle atrophy mouse model to evaluate the effects of m6 A modification on muscle mass control and FoxO3 activation. m6 A-sequencing and mass spectrometry analyses were used to establish whether histone deacetylase 4 (HDAC4) is a mediator of m6 A demethylase ALKBH5 regulation of FoxO3. A series of cellular and molecular biological experiments (western blot, immunoprecipitation, half-life assay, m6 A-MeRIP-qPCR, and luciferase reporter assays among others) were performed to investigate regulatory relationships among ALKBH5, HDAC4, and FoxO3. RESULTS: In skeletal muscles, denervation was associated with a 20.7-31.9% decrease in m6 A levels (P < 0.01) and a 35.6-115.2% increase in demethylase ALKBH5 protein levels (P < 0.05). Overexpressed ALKBH5 reduced m6 A levels, activated FoxO3 signalling, and induced excess loss in muscle wet weight (-10.3% for innervation and -11.4% for denervation, P < 0.05) as well as a decrease in myofibre cross-sectional areas (-35.8% for innervation and -33.3% for denervation, P < 0.05) during innervation and denervation. Specific deletion of Alkbh5 in the skeletal muscles prevented FoxO3 activation and protected mice from denervation-induced muscle atrophy, as evidenced by increased muscle mass (+16.0%, P < 0.05), size (+50.0%, P < 0.05) and MyHC expression (+32.6%, P < 0.05). Mechanistically, HDAC4 was established to be a crucial central mediator for ALKBH5 in enhancing FoxO3 signalling in denervated muscles. ALKBH5 demethylates and stabilizes Hdac4 mRNA. HDAC4 interacts with and deacetylates FoxO3, resulting in a significant increase in FoxO3 expression (+61.3-82.5%, P < 0.01) and activity (+51.6-122.0%, P < 0.001). CONCLUSIONS: Our findings elucidate on the roles and mechanisms of ALKBH5-mediated m6 A demethylation in the control of muscle mass during denervation and activation of FoxO3 signalling by targeting HDAC4. These results suggest that ALKBH5 is a potential therapeutic target for neurogenic muscle atrophy.

Facile synthesis of near-infrared bodipy by donor engineering for in vivo tumor targeted dual-modal imaging.

Bodipy is one of the most popular dyes for bioimaging, however, a complicated synthetic protocol is needed to create and isolate ideal near-infrared (NIR) emissive Bodipy derivatives for optical bioimaging. It is noticed that the donor species impact the wavelength when the π-conjugation system of green light emissive Bodipy is elongated via a one-step reaction. Herein, several Bodipy dyes bearing different common donors are synthesized. Their optical properties confirm that both absorption and emission peaks of the synthesized Bodipy could be tuned to NIR wavelength by using stronger donors via a facile reaction. The synthesized monocarboxyl Bodipy could conjugate with aminated PEG to yield an amphiphilic polymer, which further self-assembles into a NIR nanoparticle (NP). The NIR NP exhibits preferential tumor accumulation via the enhanced permeation and retention (EPR) effect, making it useful for tumor diagnosis by both fluorescence imaging and photoacoustic tomography.

Small Molecule, Multimodal, [18F]-PET and Fluorescence Imaging Agent Targeting Prostate-Specific Membrane Antigen: First-in-Human Study.

BACKGROUND: A first-in-human study of [18F]-BF3-Cy3-ACUPA, a small-molecule imaging agent that can be unimolecularly both positron emitting and fluorescent, is conducted to determine its safety, biodistribution, radiation dosimetry, feasibility in tumor detection by preoperative positron emission tomography (PET), as well as its intraoperative fluorescence imaging utility in patients with prostate-specific membrane antigen positive (PSMA+) tumors. METHODS: Ten patients aged 66 ± 7 years received a 6.5 ± 3.2 mCi intravenous injection of [18F]-BF3-Cy3-ACUPA and underwent PET/computed tomography (CT) imaging. Radiation dosimetry of [18F]-BF3-Cy3-ACUPA, normal organ biodistribution, and tumor uptakes were examined. Two patients were prescheduled for radical prostatectomy (RP) with extended pelvic lymphadenectomy approximately 24 hours following [18F]-BF3-Cy3-ACUPA injection and imaging. Without reinjection, intraoperative fluorescence imaging was performed on freshly excised tissue during RP. Frozen sections of excised tissue during RP were submitted for confirmatory histopathology and multiphoton fluorescence and brightfield microscopy. RESULTS: Absorbed doses by organs including the kidneys and salivary glands were similar to 68Ga-PSMA-11 imaging. [18F]-BF3-Cy3-ACUPA physiologic radiotracer accumulation and urinary/biliary excretion closely resembled the distribution of other published PSMA tracers including [18F]-JK-PSMA-7, [18F]-PSMA-1007, [18F]-DCFPyL, and [18F]-DCFBC. 19F-BF3-Cy3-ACUPA was retained in PSMA+ cancer tissues in patients for at least 24 hours, allowing for intraoperative fluorescence assessment of the prostate and of the embedded prostate cancer without contrast reinjection. After 24 hours, the imaging agent mostly decayed or cleared from the blood pool. Preoperative PET and fluorescence imaging findings were confirmed with final histopathology and multiphoton microscopy. CONCLUSION: Our first-in-human results demonstrate that [18F]-BF3-Cy3-ACUPA is safe and feasible in humans. Larger trials with this PET tracer are expected to further define its capabilities and its clinical role in the management of PSMA+ tumors, especially in prostate cancer.

A lysosome specific, acidic-pH activated, near-infrared Bodipy fluorescent probe for noninvasive, long-term, in vivo tumor imaging.

Long-term, in vivo, fluorescent cell tracking probes are useful for understanding complex cellular processes including tissue regeneration, communication, development, invasion, and cancer metastasis. A near-infrared fluorescent, water-soluble probe is particularly important for studying these biological events and processes. Herein, a lysosome specific, near-infrared Bodipy probe with increased fluorescent intensity in the acidic, lysosome environment is reported. This Bodipy probe is packaged in a nanoparticle using DSPE-PEG2000. The resulting nanoparticle is intravenously delivered to a tumor xenograft, where the fluorescent Bodipy becomes useful for non-invasive, long-term, in vivo fluorescent tumor imaging for periods greater than 36 days. These long-term, in vitro and in vitro tracking data indicate that the described Bodipy nanoparticles hold great potential for monitoring biological processes.

Small ultra-red fluorescent protein nanoparticles as exogenous probes for noninvasive tumor imaging in vivo.

Nanoparticles are excellent imaging agents for cancer, but variability in chemical structure, racemic mixtures, and addition of heavy metals hinders FDA approval in the United States. We developed a small ultra-red fluorescent protein, named smURFP, to have optical properties similar to the small-molecule Cy5, a heptamethine subclass of cyanine dyes (Ex/Em = 642/670 nm). smURFP has a fluorescence quantum yield of 18% and expresses so well in E. coli, that gram quantities of fluorescent protein are purified from cultures in the laboratory. In this research, the fluorescent protein smURFP was combined with bovine serum albumin into fluorescent protein nanoparticles. These nanoparticles are fluorescent with a quantum yield of 17% and 12-14 nm in diameter. The far-red fluorescent protein nanoparticles noninvasively image tumors in living mice via the enhanced permeation and retention (EPR) mechanism. This manuscript describes the use of a new fluorescent protein nanoparticle for in vivo fluorescent imaging. This protein nanoparticle core should prove useful as a biomacromolecular scaffold, which could bear extended chemical modifications for studies, such as the in vivo imaging of fluorescent protein nanoparticles targeted to primary and metastatic cancer, theranostic treatment, and/or dual-modality imaging with positron emission tomography for entire human imaging.

Sensitive and specific detection of tumour cells based on a multivalent DNA nanocreeper and a multiplexed fluorescence supersandwich.

A self-assembled DNA nanostructure based on a DNA nanocreeper and multiplexed fluorescence supersandwich was designed for the sensitive and specific detection of tumour cells. This nanostructure could improve the binding affinity of current aptamers and trigger signal amplification, which provide potential for the discrimination of low abundant target cells in liquid biopsy.

PET, image-guided HDAC inhibition of pediatric diffuse midline glioma improves survival in murine models.

Efforts at altering the dismal prognosis of pediatric midline gliomas focus on direct delivery strategies like convection-enhanced delivery (CED), where a cannula is implanted into tumor. Successful CED treatments require confirmation of tumor coverage, dosimetry, and longitudinal in vivo pharmacokinetic monitoring. These properties would be best determined clinically with image-guided dosimetry using theranostic agents. In this study, we combine CED with novel, molecular-grade positron emission tomography (PET) imaging and show how PETobinostat, a novel PET-imageable HDAC inhibitor, is effective against DIPG models. PET data reveal that CED has significant mouse-to-mouse variability; imaging is used to modulate CED infusions to maximize tumor saturation. The use of PET-guided CED results in survival prolongation in mouse models; imaging shows the need of CED to achieve high brain concentrations. This work demonstrates how personalized image-guided drug delivery may be useful in potentiating CED-based treatment algorithms and supports a foundation for clinical translation of PETobinostat.

Real-Time, in Vivo Correlation of Molecular Structure with Drug Distribution in the Brain Striatum Following Convection Enhanced Delivery.

The blood-brain barrier (BBB) represents a major obstacle in delivering therapeutics to brain lesions. Convection-enhanced delivery (CED), a method that bypasses the BBB through direct, cannula-mediated drug delivery, is one solution to maintaining increased, effective drug concentration at these lesions. CED was recently proven safe in a phase I clinical trial against diffuse intrinsic pontine glioma (DIPG), a childhood cancer. Unfortunately, the exact relationship between drug size, charge, and pharmacokinetic behavior in the brain parenchyma are difficult to observe in vivo. PET imaging of CED-delivered agents allows us to determine these relationships. In this study, we label different modifications of the PDGFRA inhibitor dasatinib with fluorine-18 or via a nanofiber-zirconium-89 system so that the effect of drug structure on post-CED behavior can accurately be tracked in vivo, via PET. Relatively unchanged bioactivity is confirmed in patient- and animal-model-derived cell lines of DIPG. In naïve mice, significant individual variability in CED drug clearance is observed, highlighting a need to accurately understand drug behavior during clinical translation. Generally, the half-life for a drug to clear from a CED site is short for low molecular weight dasatinib analogs that bare different charge; 1-3 (1, 32.2 min (95% CI: 27.7-37.8), 2, 44.8 min (27.3-80.8), and 3, 71.7 min (48.6-127.6) minutes) and is much longer for a dasatinib-nanofiber conjugate, 5, (42.8-57.0 days). Positron emission tomography allows us to accurately measure the effect of drug size and charge in monitoring real-time drug behavior in the brain parenchyma of live specimens.

A Fluorescent, [18F]-Positron-Emitting Agent for Imaging Prostate-Specific Membrane Antigen Allows Genetic Reporting in Adoptively Transferred, Genetically Modified Cells.

Clinical trials involving genome-edited cells are growing in popularity, where CAR-T immunotherapy and CRISPR/Cas9 editing are more recognized strategies. Genetic reporters are needed to localize the molecular events inside these cells in patients. Specifically, a nonimmunogenic genetic reporter is urgently needed as current reporters are immunogenic due to derivation from nonhuman sources. Prostate-specific membrane antigen (PSMA) is potentially nonimmunogenic due to its natural, low-level expression in select tissues (self-MHC display). PSMA overexpression on human prostate adenocarcinoma is also visible with excellent contrast. We exploit these properties in a transduced, two-component, Human-Derived, Genetic, Positron-emitting, and Fluorescent (HD-GPF) reporter system. Mechanistically analogous to the luciferase and luciferin reporter, PSMA is genetically encoded into non-PSMA expressing 8505C cells and tracked with ACUPA-Cy3-BF3, a single, systemically injected small molecule that delivers positron emitting fluoride (18F) and a fluorophore (Cy3) to report on cells expressing PSMA. PSMA-lentivirus transduced tissues become visible by Cy3 fluorescence, [18F]-positron emission tomography (PET), and γ-scintillated biodistribution. HD-GPF fluorescence is visible at subcellular resolution, while a reduced PET background is achieved in vivo, due to rapid ACUPA-Cy3-BF3 renal excretion. Co-transduction with luciferase and GFP show specific advantages over popular genetic reporters in advanced murine models including, a "mosaic" model of solid-tumor intratumoral heterogeneity and a survival model for observing postsurgical recurrence. We report an advanced genetic reporter that tracks genetically modified cells in entire animals and with subcellular resolution with PET and fluorescence, respectively. This reporter system is potentially nonimmunogenic and will therefore be useful in human studies. PSMA is a biomarker of prostate adenocarcinoma and ACUPA-Cy3-BF3 potential in radical prostatectomy is demonstrated.

Soft Biomaterial-based Nanocrystal in Pharmaceutical.

BACKGROUND AND OBJECTIVE: Bio-soft material, a class of derivatives of the natural or synthetic material, is getting more and more prevalent in biomedical researches and applications due to the advantages such as in-vivo biodegradation, good water solubility and designable targeting ability. With the presence of bio-soft materials, the drug nanocrystal can be easily generated and aggregated in a feasible process. Given the promising application of the bio-soft material in biological and chemical research, it is valuable to discuss the crucial step in designing bio-soft materials and analyze the emerging properties of bio-soft materials. METHODS: A comprehensive literature survey in the field of bio-soft material development and analysis has been conducted. The collected data and figures were meticulously analyzed and interpreted. RESULTS: In this review, the details of bio-soft materials based nanocrystal were demonstrated in three sections with respect to different materials. In each section, the pros and cons for each bio-soft material and its derivatives were elaborately listed and discussed. CONCLUSION: The review enables an insightful discussion about the properties and the applications of existing biosoft material. It may contribute to the further researches about bio-soft material development and analysis.

An [18F]-Positron-Emitting, Fluorescent, Cerebrospinal Fluid Probe for Imaging Damage to the Brain and Spine.

Fluorescein is modified to bear 18F so that it can act as both a positron emitter, and a fluorophore, allowing detection by positron emission tomography (PET), scintillation, and fluorescent imaging (FL). [18F]-2 is injected into the intrathecal space of rats and used to observe the cerebrospinal fluid (CSF) that bathes the brain and spine. Injury in three different applications is visualized with [18F]-2: 1) detection of a 0.7 mm paranasal-sinus CSF leak (CSFL); 2) detection of 0.5 mm puncture damage to the thoracic spine (acute spinal cord injury); and 3) detection of intracerebral hemorrhage/edema because of traumatic brain injury. In all models, the location of injury is visualized with [18F]-2 at high resolution. [18F]-2 PET imaging may be a superior alternative to current clinical contrast myelography and 131I, 111In or 99mTc radionuclide cisternography. Like fluorescein, [18F]-2 may also have other uses in diagnostic or fluorescence guided medicine.

Development of Dual-Aptamers for Constructing Sandwich-Type Pancreatic Polypeptide Assay.

Pancreatic polypeptide (PP) is a specific biomarker of nonfunctional pancreatic neuroendocrine tumors (NF-pNETs). Clinical significance of PP inspires researchers to make great efforts in developing sensitive and specific sensors. However, there is no existing biosensor for detecting PP that combines facility and functionality. Addressing this challenge, a pair of aptamers which could be used to develop a sandwich assay for PP is reported. First, several high affinity aptamers are screened through graphene oxide-based SELEX, and appropriate dual-aptamers which could bind to different epitopes of PP are identified through fluorescence assays. Then the feasibility of the dual-aptamers for constructing the sandwich assay is validated via dynamic light scattering. This sandwich assay shows considerable sensitivity and specificity. The above results imply that the dual-aptamers have the potential toward developing novel sensors for PP in clinical samples.