Coagulation-Inspired Direct Fibrinogen Assay Using Plasmonic Nanoparticles Functionalized with Red Blood Cell Membranes

Magnetic Nanoagent Coated with an Activated Macrophage Membrane for Colorimetric Detection of Bacteria

The construction of cell mimics replicating the surface landscape and biological functions of the cell membrane offers promising prospects for biomedical research and applications. Inspired by the inherent recognition capability of immune cells toward pathogens, we have fabricated activated macrophage membrane-coated magnetic silicon nanoparticles (aM-MSNPs) in this work as an isolation and recognition tool for enhanced bacterial analysis. Specifically, the natural protein receptors on the activated macrophage membrane endow the MSNPs with a broad-spectrum binding capacity to different pathogen species. By further incorporation of a tyramide amplification strategy, direct naked-eye analysis of specific bacteria with a detection limit of 10 CFU/mL can be achieved. Moreover, application to the diagnosis of urinary tract infections has also been validated, and positive samples spiked with bacteria can be clearly distinguished with an accuracy of 100%. This work may enrich cell membrane-based architectures and provide an experimental paradigm for point-of-care testing (POCT) detection of bacteria.

Development of biosensors for detection of fibrinogen: a review

Fibrinogen as a major inflammation marker and blood coagulation factor has a direct impact on the health of humanity. The variations in fibrinogen content lead to risky conditions such as bleeding and cardiovascular diseases. So, accurate methods for monitoring of this glycoprotein are of high importance. The conventional methods, such as the Clauss method, are time consuming and require highly specialized expert analysts. The development of fast, simple, easy to use, and inexpensive methods is highly desired. In this way, biosensors have gained outstanding attention since they offer means for performing analyses at the points-of-care using self-testing devices, which can be applied outside of clinical laboratories or hospital. This review indicates that different electrochemical and optical sensors have been successfully implemented for the detection of fibrinogen under normal levels of fibrinogen in plasma. The biosensors for the detection of fibrinogen have been designed based on the quartz crystal microbalance, field-effect transistor, electrochemical impedance spectroscopy, amperometry, surface plasmon resonance, localized surface plasmon resonance, and colorimetric techniques. Also, this review demonstrates the utility of the application of nanoparticles in different detection techniques.

Erythrocyte membrane-camouflaged DNA-functionalized upconversion nanoparticles for tumor-targeted chemotherapy and immunotherapy

A synergistic combination of treatment with immunogenic cell death (ICD) inducers and immunoadjuvants may be a practical way to boost the anticancer response and successfully induce an immune response. The use of HR@UCNPs/CpG-Apt/DOX, new biomimetic drug delivery nanoparticles generated to combat breast cancer, is reported here as a unique strategy to produce immunogenicity and boost cancer immunotherapy. HR@UCNPs/CpG-Apt/DOX (HR-UCAD) consists of two parts. The core is composed of an immunoadjuvant CpG (a toll-like receptor 9 agonist) fused with a dendritic cell-specific aptamer sequence (CpG-Apt) to decorate upconversion nanoparticles (UCNPs) with the successful intercalation of doxorubicin (DOX) into the consecutive base pairs of Apt-CpG to construct an immune nanodrug UCNPs@CpG-Apt/DOX. The targeting molecule hyaluronic acid (HA) was inserted into a red blood cell membrane (RBCm) to form the shell (HR). HR-UCAD possessed a strong capacity to specifically induce ICD. Following DOX-induced ICD of cancer cells, sufficient exposure to tumor antigens and UCNPs@CpG-Apt (UCA) activated the tumor-specific immune response and reversed the immunosuppressive tumor microenvironment. In addition, HR-UCAD has good biocompatibility and increases the active tumor-targeting effect. Furthermore, HR-UCAD exhibits excellent near-infrared upconversion luminescence emission at 804 nm under irradiation with a 980 nm laser, which has great potential in biomedical imaging. Thus, the RBCm-camouflaged drug delivery system is a promising targeted chemotherapy and immunotherapy nanocomplex that could be used for effective targeted breast cancer treatment.

Biomimetic Biomembrane Encapsulation and Targeted Delivery of a Nitric Oxide Release Platform for Therapy of Parkinson's Disease

The existence of the blood-brain barrier (BBB) and the complex inflammatory environment in the brain are two major obstacles in the treatment of Parkinson's disease (PD). As a target group, we modified the red blood cell membrane (RBCM) on the surface of upconversion nanoparticles (UCNPs) in this study to effectively target the brain. Mesoporous silicon, coated with UCNPs (UCM), was loaded with S-nitrosoglutathione (GSNO) as the nitric oxide (NO) donor. Then, UCNPs were excited to emit green light (540 nm) by 980 nm near-infrared (NIR). In addition, it produced a light-responsive anti-inflammatory effect by promoting the release of NO from GSNO and lowering the brain's level of proinflammatory factors. A series of experiments demonstrated that this strategy could effectively mitigate the inflammatory response damage of neurons in the brain.

Artificial nano-red blood cells nanoplatform with lysosomal escape capability for ultrasound imaging-guided on-demand pain management

Postoperative pain management would benefit significantly from an anesthetic that could take effect in an on-demand manner. An ultrasound would be an appropriate tool for such nanoplatform because it is widely used in clinical settings for ultrasound-guided anesthesia. Herein, we report a nanoplatform for postoperative on-demand pain management that can effectively enhance their analgesic time while providing ultrasonic imaging. Levobupivacaine and perfluoropentane were put into dendritic mesoporous silica and covered with red blood cell membranes to make the pain relief last longer in living organisms. The generated nanoplatform with gas-producing capability is ultrasonic responsive and can finely escape from the lysosomal in cells under ultrasound irradiation, maximizing the anesthetic effect with minimal toxicity. Using an incision pain model in vivo, levobupivacaine's sustained and controlled release gives pain reduction for approximately 3 days straight. The duration of pain relief is over 20 times greater than with a single injection of free levobupivacaine. Effective pain management was reached in vivo, and the pain reduction was enhanced by repeated ultrasonic irradiation. There was no detectable systemic or tissue injury under either of the treatments. Thus, our results suggest that nanoplatform with lysosomal escape capability can provide a practical ultrasound imaging-guided on-demand pain management strategy. STATEMENT OF SIGNIFICANCE: On-demand pain management is essential to postoperative patients. However, the traditional on-demand pain management strategy is hampered by the limited tissue penetration depth of near-infrared stimuli and the lack of proper imaging guidance. The proposed research is significant because it provides a nanoplatform for deep penetrated ultrasound controlled pain management under clinical applicable ultrasound imaging guidance. Moreover, the nanoplatform with prolonged retention time and lysosomal escape capability can provide long-term pain alleviation. Therefore, our results suggest that nanoplatform with lysosomal escape capability can provide an effective strategy for ultrasound imaging-guided on-demand pain management.

Influence of lung cancer model characteristics on tumor targeting behavior of nanodrugs

Evidence is mounting that there is a significant gap between the antitumor efficacy of nanodrugs in preclinical mouse tumor models and in clinical human tumors, and that differences in tumor models are likely to be responsible for this gap. Herein, we investigated the enhanced permeability and retention (EPR) effect in mouse lung cancer models with different tumor growth rates, volumes and locations, and analyzed the nanodrug tumor targeting behaviors limited by tumor vascular pathophysiological characteristics in various tumor models. The results showed that the fast-growing tumors were characterized by lower vascular tight junctions, leading to higher vascular paracellular transport activity and nanodrug tumor accumulation. The paracellular transport activity increased with the growth of tumor, but the vascular density and transcellular transport activity decreased, and as a result, the average tumor accumulation of passive targeting nanodrugs decreased. Orthotopic tumors were rich in blood vessels, but had low vascular transcellular and paracellular transport activities, making it difficult for nanodrug accumulation in orthotopic tumors via passive targeting strategies. The antitumor efficacy of passive targeting nanodrugs in various lung cancer-bearing mice validated the aforementioned nanodrug accumulation behavior, and nanodrugs based on the angiogenesis-tumor sequential targeting strategy achieved obviously improved efficacy in orthotopic lung cancer-bearing mice. These results suggest that the EPR effect varies in different tumor models and should not be used as a universal targeting strategy for antitumor nanodrugs. Besides, attention should be paid to the animal tumor models in the evaluation of nanodrugs so as to avoid exaggerating the antitumor efficacy.

Intravenous Hemostats: Foundation, Targeting, and Controlled-Release

Uncontrollable blood loss is the greatest cause of mortality in prehospital patients and the main source of disability and death in hospital care. Compared with external hemostats, intravenous hemostats are more appropriate for preventing and treating uncontrolled bleeding in vivo and large bleeding on the body surface. This Review initially establishes intravenous hemostats' response basis, including the coagulation mechanism, fibrinolytic pathway, and protein corona. Second, the study of advancement of intravenous hemostat targeting was expanded from two perspectives, cellular hemostatic agents and synthetic hemostatic agents. Meanwhile, after discussing the progress of controlled-release intravenous hemostats with platelets as the stimuli, this Review offers insight into the possibility of controlled-release intravenous hemostats with microenvironment as the stimuli, combining the studies of controlled-release targeted thrombolysis.

Synergistic chemotherapy and phototherapy based on red blood cell biomimetic nanomaterials

Novel drug delivery systems (DDSs) have become the mainstay of research in targeted cancer therapy. By combining different therapeutic strategies, potential DDSs and synergistic treatment approaches are needed to effectively deal with evolving drug resistance and the adverse effects of cancer. Nowadays, developing and optimizing human cell-based DDSs has become a new research strategy. Among them, red blood cells can be used as DDSs as they significantly enhance the pharmacokinetics of the transported drug cargo. Phototherapy, as a novel adjuvant in cancer treatment, can be divided into photodynamic therapy and photothermal therapy. Phototherapy using erythropoietic nanocarriers to mimic the unique properties of erythrocytes and overcome the limitations of existing DDSs shows excellent prospects in clinical settings. This review provides an overview of the development of photosensitizers and research on bio-nano-delivery systems based on erythrocytes and erythrocyte membranes that are used in achieving synergistic outcomes during phototherapy/chemotherapy.

Hemolysis-Inspired, Highly Sensitive, Label-Free IgM Detection Using Erythrocyte Membrane-Functionalized Nanomechanical Resonators

Immunoglobulin detection is important for immunoassays, such as diagnosing infectious diseases, evaluating immune status, and determining neutralizing antibody concentrations. However, since most immunoassays rely on labeling methods, there are limitations on determining the limit of detection (LOD) of biosensors. In addition, although the antigen must be immobilized via complex chemical treatment, it is difficult to precisely control the immobilization concentration. This reduces the reproducibility of the biosensor. In this study, we propose a label-free method for antibody detection using microcantilever-based nanomechanical resonators functionalized with erythrocyte membrane (EM). This label-free method focuses on the phenomenon of antibody binding to oligosaccharides (blood type antigen) on the surface of the erythrocyte. We established a method for extracting the EM from erythrocytes and fabricated an EM-functionalized microcantilever (MC), termed EMMC, by surface-coating EM layers on the MC. When the EMMC was treated with immunoglobulin M (IgM), the bioassay was successfully performed in the linear range from 2.2 pM to 22 nM, and the LOD was 2.0 pM. The EMMC also exhibited excellent selectivity compared to other biomolecules such as serum albumin, γ-globulin, and IgM with different paratopes. These results demonstrate that EMMC-based nanotechnology may be utilized in criminal investigations to identify blood types with minimal amounts of blood or to evaluate individual immunity through virus-neutralizing antibody detection.

Dendronized Gelatin-Mediated Synthesis of Gold Nanoparticles

Thermoresponsive dendronized gelatins (GelG1) or gelatin methacrylates (GelG1MA) were used as precursors to modulate the efficient reduction of Au(III) to form stable gold nanoparticles (AuNPs) through UV irradiation. These dendronized gelatins were obtained through the amidation of gelatin or gelatin methacrylates with dendritic oligoethylene glycols (OEGs). Crowded OEG dendrons along the gelatin backbones create a hydrophobic microenvironment, which promotes the reduction of Au(III). Gelatin backbones act as ligands through the electron-rich groups to facilitate the reduction, while the dendritic OEGs provide shielding effects through crowding to form a hydrophobic microenvironment, which not only enhances the reduction but also stabilize the formed AuNPs through encapsulation. The effects of dendron coverage on the dendronized biomacromolecules and their thermoresponsiveness on the reduction kinetics were examined. Dendronized gelatin/AuNPs hydrogels were further prepared through the in situ photo-crosslinking of GelG1MA. The modification of natural macromolecules through dendronization presented in this report facilitates a novel platform for the environmentally friendly synthesis of noble metal nanoparticles, which may form a new strategy for developing smart nano-biosensors and nano-devices.

A point-of-care microfluidic channel-based device for rapid and direct detection of fibrinogen in whole blood

Hemorrhage is the leading cause of preventable death in civilian and battlefield traumatic injuries. Patients with severe traumatic hemorrhagic shock are more likely to be deficient in fibrinogen than those with other coagulation factors, and hypofibrinogenemia is an independent risk factor for mortality. Thus, rapid detection of fibrinogen levels is of great importance in these patients during damage control resuscitation. Plasma is used as an analyte in fibrinogen detection, which restricts the use of existing devices in emergencies. To meet the needs of on-site detection, we developed a point-of-care microfluidic channel-based device for direct measurement of fibrinogen concentration in whole blood. In our method, thrombin is dispersed on a reaction strip to initiate conversion of fibrinogen to fibrin. The permeability of the resulting blood clots depends on the fibrinogen level. A hydrophobic plastic protection flake between the reaction strip and a wicking strip is then removed to allow flow of unclotted blood. The rate of blood flow along the wicking strip was inversely related to the fibrinogen concentration. The whole process could be completed in as fast as 5 minutes for a whole blood sample size of 150 μL, and yielded accurate results ranging from 0 to 4 g L^-1, which were unaffected by Ca²⁺, blood lipids, hematocrit, warfarin and tissue plasminogen activators (tPAs). Results using clinical whole blood samples were also highly consistent with those using an automatic coagulation analyzer, yielding a Pearson correlation coefficient of up to 0.919. This approach has potential for allowing rapid diagnosis of fibrinogen concentration in critically ill bleeding patients in different settings, thus helping to judge the suitability of fibrinogen replacement therapy (FRT) in cases of emergency bleeding and in patients at risk of thrombosis due to hyperfibrinogenemia.

Cell-membrane-inspired polymers for constructing biointerfaces with efficient molecular recognition

Fabrication of devices that accurately recognize, detect, and separate target molecules from mixtures is a crucial aspect of biotechnology for applications in medical, pharmaceutical, and food sciences. This technology has also been recently applied in solving environmental and energy-related problems. In molecular recognition, biomolecules are typically complexed with a substrate, and specific molecules from a mixture are recognized, captured, and reacted. To increase sensitivity and efficiency, the activity of the biomolecules used for capture should be maintained, and non-specific reactions on the surface should be prevented. This review summarizes polymeric materials that are used for constructing biointerfaces. Precise molecular recognition occurring at the surface of cell membranes is fundamental to sustaining life; therefore, materials that mimic the structure and properties of this particular surface are emphasized in this article. The requirements for biointerfaces to eliminate nonspecific interactions of biomolecules are described. In particular, the major issue of protein adsorption on biointerfaces is discussed by focusing on the structure of water near the interface from a thermodynamic viewpoint; moreover, the structure of polymer molecules that control the water structure is considered. Methodologies enabling stable formation of these interfaces on material surfaces are also presented.

Biocompatible poly(galacturonic acid) micro/nanogels with controllable degradation via tunable chemical crosslinking

Here, one-pot labor-less preparation of two different polygalacturonic acid (PGA) micro/nanogel formulations, PGA-1 and PGA-2, by respectively crosslinking the PGA chains with divinyl sulfone (DVS) and trimethylolpropane triglycidyl ether (TMPGDE) were reported. Various crosslinker ratios, 2.5, 10, 50, and 100% were used for both crosslinkers to demonstrate the tunability of their degradation properties. The PGA micro/nanogels were found spherical-shaped porous particles in 0.5-5.0 μm size range by SEM. The hydrolytic degradation and stability of PGA micro/nanogels in pH 1.0, 7.4, and 9.0 buffer solutions can be controlled by changing the degree of crosslinking. Accordingly, 32 ± 8% and 36 ± 2% weight losses were attained for PGA-1-10% and PGA-2-10% micro/nanogels at pH 1, respectively, and 46 ± 6%, and 68 ± 6% degradations were determined at pH 7.4 within 4 weeks. However, no degradation was observed for both PGA-based micro/nanogel formulations prepared at 25% and 100% crosslinker ratios at all pH conditions. All PGA-based micro/nanogels were totally degraded within 7-10 days at pH 9.0. In the presence of pectinase and amyloglucosidase enzymes, all formulations of PGA micro/nanogels showed more than 80% degradation within 12 h. Furthermore, both PGA formulations showed no significant cytotoxicity against L929 fibroblast cells with 90% and above cell viability up to 250 mg/mL concentrations.

Engineered red blood cell membrane for sensitive and precise electrochemical detection of salivary exosomes

As a kind of promising non-invasive biomarker, exosomes naturally occurring in saliva have recently attracted considerable attention in view of their potential use in the diagnosis of oral diseases. Herein, we propose a new electrochemical method for the sensitive and precise detection of salivary exosomes. A red blood cell membrane (RBCM) engineered with CD63 aptamer is the core element of the method and is used to camouflage a gold electrode, thus giving the electrode superior antifouling and targeting ability. Target exosomes presented in saliva are recognized and captured by the highly specific interaction between the exosomal CD63 and the aptamers engineered in RBCM. Then, silver nanoparticles modified with CD63 aptamers are recruited onto the electrode surface to generate significant electrochemical signals, which enables the sensitive detection of target exosomes. By using human oral squamous cell carcinoma CAL27 cell-derived exosomes as a model, the method allows target salivary exosome detection in a wide linear range from 5 × 10² to 1 × 10⁶ particles per mL and a low detection limit of 2.07 × 10² particles per mL. Moreover, the method displays good reproducibility and is feasible for detecting target exosomes with high precision in saliva samples. Overall, the method may provide a useful tool for salivary exosome detection and may have great potential for practical use in the clinical diagnosis of oral diseases.

Recent advances in cell membrane camouflage-based biosensing application

Cell membrane, a semi-permeable membrane composed of phospholipid bilayers, is a natural barrier to prevent extracellular substances from freely entering the cell. Cell membrane with selective permeability and fluidity ensures the relative stability of the intracellular environment and enables various biochemical reactions to smoothly operate in an orderly manner. Inspired by the natural composition and transport process, various cell membranes and synthetic bionic films as the mimics of cell membranes have emerged as appealing camouflage materials for biosensing applications. The membranes are devoted to surface modification and substance delivery, and realize the detection or in situ analysis of multiple biomarkers, such as glucose, nucleic acids, virus, and circulating tumor cells. In this review, we summarize the recent advances in cell membrane camouflage-based biosensing applications, mainly focusing on the use of the membranes extracted from natural cells (e.g., blood cells and cancer cells) as well as biomimetic membranes. Materials and surfaces camouflaged with cell membranes are shown to have superior stability and biocompatibility as well as intrinsic properties of original cells, which greatly facilitate their use in biosensing. In specific, camouflage with blood cell membranes bestows low immunogenicity and prolonged blood circulation time, camouflage with cancer cell membranes provides homologous targeting ability, and camouflage with biomimetic membranes endows considerable plasticity for functionalization. Further research is expected to focus on the deeper understanding of cell-specific properties of membranes and the exploration of hybrid membranes, which might provide new development opportunities for cell membrane camouflage-based biosensing application.

Red blood cells: The metamorphosis of a neglected carrier into the natural mothership for artificial nanocarriers

Drug delivery research pursues many types of carriers including proteins and other macromolecules, natural and synthetic polymeric structures, nanocarriers of diverse compositions and cells. In particular, liposomes and lipid nanoparticles represent arguably the most advanced and popular human-made nanocarriers, already in multiple clinical applications. On the other hand, red blood cells (RBCs) represent attractive natural carriers for the vascular route, featuring at least two distinct compartments for loading pharmacological cargoes, namely inner space enclosed by the plasma membrane and the outer surface of this membrane. Historically, studies of liposomal drug delivery systems (DDS) astronomically outnumbered and surpassed the RBC-based DDS. Nevertheless, these two types of carriers have different profile of advantages and disadvantages. Recent studies showed that RBC-based drug carriers indeed may feature unique pharmacokinetic and biodistribution characteristics favorably changing benefit/risk ratio of some cargo agents. Furthermore, RBC carriage cardinally alters behavior and effect of nanocarriers in the bloodstream, so called RBC hitchhiking (RBC-HH). This article represents an attempt for the comparative analysis of liposomal vs RBC drug delivery, culminating with design of hybrid DDSs enabling mutual collaborative advantages such as RBC-HH and camouflaging nanoparticles by RBC membrane. Finally, we discuss the key current challenges faced by these and other RBC-based DDSs including the issue of potential unintended and adverse effect and contingency measures to ameliorate this and other concerns.

Aquaporin-Incorporated Graphene-Oxide Membrane for Pressurized Desalination with Superior Integrity Enabled by Molecular Recognition

Aquaporins (AQPs), the natural water channel, have been actively investigated for overcoming the limitations of conventional desalination membranes. An AQP-based biomimetic high-pressure desalination membrane is designed by tethering AQP-carrying red blood cell membrane (RBCM) vesicles onto graphene oxide (GO). RBCMs with AQPs are incorporated into GO based on the molecular recognition between the integrin of RBCM and Arginine-Glycine-Aspartate (RGD) ligand on the GO surface. GO is pre-functionalized with the Glycine-Arginine-Glycine-Aspartate-Serine peptide to capture RBCMs. RBCMs are inserted between GO flakes through the material-specific interaction between integrin of RBCM and RGD ligand, thus ensuring sufficient coverage of channels/defects in the GO for the full functioning of the AQPs. The incorporated AQPs are not completely fixed at the GO, as tethering is mediated by the integrin-RGD pair, and suitable AQP flexibility for appropriate functioning is guaranteed without frictional hindrance from the solid substrate. The integrity of the GO-RBCMs binding can provide mechanical strength for enduring high-pressure reverse-osmosis conditions for treating large amounts of water. This biomimetic membrane exhibits 99.1% NaCl rejection and a water permeance of 7.83 L m-2 h-1 bar-1 at 8 bar with a 1000-ppm NaCl feed solution, which surpasses the upper-bound line of current state-of-the-art membranes.

Erythrocyte-camouflaged biosensor for α-hemolysin detection

Without appropriate treatment, Staphylococcus aureus (S. aureus) infection can cause life-threatening diseases (e.g., meningitis, pneumonia, bacteremia, and sepsis). However, a rapid and accurate point-of-care test for the infection remains challenging. The bacterium secretes α-hemolysin (Hla), which spontaneously binds to the cell membrane of erythrocyte, and eventually lyses the cell via pore formation. Taking advantage of this phenomenon, we apply the erythrocyte membrane (EM) extracted from human whole blood as a novel bioreceptor for detecting Hla, fabricating erythrocyte-camouflaged biosensors (ECB) by coating EM onto electrochemical impedance electrodes. We verify the existence of EM on the ECB by using confocal microscopy and atomic force microscopy. We demonstrate that ECBs sensitively detect Hla spiked in phosphate buffer saline and human serum. Also, the sensor shows higher sensitivity to Hla than major blood proteins, such as human serum albumin, fibrinogen, and gamma globulin. Specifically, the signal intensities for Hla are 8.8-12.7 times higher than those in the same concentration of those blood proteins. The detection limit of the ECB for Hla is 1.9 ng/ml while the dynamic range is 0.0001-1 mg/ml. Finally, we validate the constant sensing performance of ECB with 99.0 ± 5.6% accuracy for 35 days of storage.

Selective colorimetric urine glucose detection by paper sensor functionalized with polyaniline nanoparticles and cell membrane

For the diabetes diagnosis, noninvasive methods are preferred to invasive methods; urine glucose measurement is an example of a noninvasive method. However, conventional noninvasive methods for urine glucose measurement are not intuitive. Furthermore, such methods exhibit low selectivity because they can detect interfering molecules in addition to glucose. Herein, we fabricate a noninvasive, intuitive, and highly selective paper sensor consisting of polyaniline nanoparticles (PAni-NPs) and red blood cell membranes (RBCMs). The PAni-NPs (adsorbed on the paper) are highly sensitive to hydrogen ions and change color from emeraldine blue to emeraldine green within a few seconds. The RBCM (coated on the PAni-NP-adsorbed paper) having the glucose transporter-1 protein plays the role of a smart filter that transports glucose but rejects other interfering molecules. In particular, the selectivity of the RBCM-coated PAni-NP-based paper sensor was approximately improved ∼85%, compared to the uncoated paper sensors. The paper sensor could detect urine glucose over the range of 0-10 mg/mL (0-56 mM), with a limit of detection of 0.54 mM. The proposed paper sensor will facilitate the development of a highly selective and colorimetric urine glucose monitoring system.