A novel ratiometric peptide-based fluorescent probe for sequential detection of Hg2+ and S2- ions and its application in living cells and zebrafish imaging

A novel dual-function peptide-based fluorescent probe with large Stokes shift for the simultaneous detection and quantification of Ag(I) and Hg(II) ions

Achieving highly selective detections of Ag+ and Hg2+ is of great importance because their excessive emission can cause many diseases. Herein, a novel large Stokes shift fluorescent probe DKT based on dansyl fluorophore modified peptide biomolecules (NH2-Thr-Lys-Thr-NH2) was successfully synthesized, which can simultaneously detect Ag+ (turn on) and Hg2+ (turn off) based on different fluorescent response patterns in 100% aqueous solution. DKT also enables quantitative detection of Ag+ and Hg2+ with LODs of 37.1 nM and 26.7 nM, respectively. Besides, ESI-HRMS spectra, Job's plot, and fluorometric titration confirmed that the binding stoichiometry was determined to be 2: 1 between DKT and Ag+/Hg2+. Moreover, DKT has good fluorescence stability and rapidly detected Ag+ and Hg2+ over a wide pH range. Furthermore, DKT was applied to quantitative detect Ag+ and Hg2+ in three actual water samples, three tea samples and watermelon juice, which exhibited that DKT has good potential for accuracy in environmental monitoring and water quality control. Additionally, the results of fluorescence bioimaging showed that DKT had significant distinguishing ability to detect Ag+ and Hg2+ in living cells and zebrafish larvae. More importantly, smartphone App platform based on DKT not only provided a reliable new method for the field quantitative monitoring of Ag+ and Hg2+, but also expanded its application prospect in the field of heavy metal ions pollution detection.

Hydrogen Sulfide detection: Recent advancement and future perspectives towards Fluorescence as a Versatile Biophysical Method

Hydrogen Sulfide (H2S) is an essential gaseous signaling molecule involved in various physiological processes, including vasodilation, neurotransmission, and anti-inflammatory responses. Accurate detection and quantification of H2S in biological systems are crucial for elucidating its physiological and pathological roles. Fluorescent probes have emerged as indispensable tools for H2S detection, offering high sensitivity, specificity, and the ability for real-time and non-invasive monitoring. This review discusses recent advances in the design and development of fluorescent probes for H2S detection, focusing on their mechanisms, properties, and applications. We explore the different strategies employed in probe design, including reduction-based mechanisms, nucleophilic addition reactions, and cleavage of sulfide bonds. Innovations such as ratiometric probes, two-photon fluorescent probes, and multi-functional probes have significantly enhanced the capabilities of H2S detection. These advancements have facilitated cellular and subcellular imaging, real-time monitoring in live organisms, and the investigation of H2S-related pathologies. Despite these progresses, challenges remain, including improving probe selectivity, stability, and biocompatibility, as well as developing methods for accurate quantification in complex biological matrices. Future research directions include designing probes with higher selectivity and sensitivity, integrating advanced computational modeling, and combining fluorescent probes with mass spectrometry for precise quantification. The continued development of sophisticated fluorescent probes will expand our understanding of H2S biology, offering new insights into its physiological and pathological roles and paving the way for novel therapeutic strategies.

A neoteric smartphone-assisted colorimetric and fluorometric dual-mode probe based on anthraquinone derived Schiff base for wide-range pH and Cu2+/S2- determination in bioimaging

The fluctuation of ion content has an important effect on human health and ecological environment. Herein, a novel colorimetric and fluorescent dual mode probe (DMHB) has been designed via the imine bond bridging of anthraquinone derivative dye and salicyl hydrazide. The DMHB displays significance wide-range pH dependent spectral behavior (pKa 5.07), which is based on proton dissociation reaction on phenol hydroxyl group. By combining with smartphone, DMHB can be utilized as an outstanding visual sensor for the on-site detection of H+. Furthermore, DMHB demonstrates a particular response to Cu2+ and S2- accompanied by a naked-eye color and fluorescence change. Importantly, DMHB allowed for accurate quantification of wide-range pH, combined with smartphones, to build a sensing platform for the detection of pH for biomedical and environmental analysis. Hence, DMHB not only provides a powerful tool for effectively differentiating tumor cells from normal cells, but also provides valuable insights for the development of imaging H+ fluctuations and Cu2+/S2- in different bio-organisms, thereby showcasing the exceptional capabilities of probe in environmental and bioimaging.

Mo-doped carbon-dots nanozyme with peroxide-like activity for sensitive and selective smartphone-assisted colorimetric S2- ion detection and antibacterial application

Sulfur ion (S2-) plays a significant and considerable role in many living organisms and ecosystems, while its abnormal content can pose a serious hazard to human health and ecological environment. Hence, it is extremely meaningful to construct a highly sensitive and selective analytical platform for S2- detection in complex microenvironment, particularly in biological systems. In this study, phosphomolybdic acid and L-Arg were utilized to prepare a new molybdenum doped carbon-dots nanozyme (Mo-CDs) with great peroxidase-like activity by one-step hydrothermal approach. In the presence of H2O2, Mo-CDs converted 3,3',5,5'-tetramethyl benzidine (TMB) into blue oxTMB, but S2- strongly reduced the blue solution to colorless and then brown, which established significant selectivity toward S2-. Mo-CDs illustrated a wide linear range (2.5 μM-900 μM) and low detection limit (LOD = 76 nM) by ultraviolet and smartphone-assisted visualized colorimetric analysis. Especially, the smartphone-assisted analysis platform successfully realized quick, portable, sensitive and visible identification of S2- with high recovery (95.7-106.7 %) and excellent specificity in water samples. More importantly, Mo-CDs was developed to antibacterial applications based on good peroxidase-like activity. This research not only constructed a new and efficient carbon-dots nanozyme and a low-cost, portable, visual analysis platform for real-time detection of S2-, but also proposed a novel design strategy and methodology for exploiting multifunctional nanozyme detection tool with great practical application.

Detection of Hg2+ Using a Dual-Mode Biosensing Probe Constructed Using Ratiometric Fluorescent Copper Nanoclusters@Zirconia Metal-Organic Framework/N-Methyl Mesoporphyrin IX and Colorimetry G-Quadruplex/Hemin Peroxidase-Mimicking G-Quadruplex DNAzyme

Mercury (Hg2+) has been recognized as a global pollutant with a toxic, mobile, and persistent nature. It adversely affects the ecosystem and human health. Already developed biosensors for Hg2+ detection majorly suffer from poor sensitivity and specificity. Herein, a colorimetric/fluorimetric dual-mode sensing approach is designed for the quantitative detection of Hg2+. This novel sensing approach utilizes nanofluorophores, i.e., fluorescent copper nanoclusters-doped zirconia metal-organic framework (CuNCs@Zr-MOF) nanoconjugate (blue color) and N-methyl mesoporphyrin IX (NMM) (red color) in combination with peroxidase-mimicking G-quadruplex DNAzyme (PMDNAzyme). In the presence of Hg2+, dabcyl conjugated complementary DNA with T-T mismatches form the stable duplex with the CuNCs@Zr-MOF@G-quadruplex structure through T-Hg2+-T base pairing. It causes the quenching of fluorescence of CuNCs@Zr-MOF (463 nm) due to the Förster resonance energy transfer (FRET) system. Moreover, the G-quadruplex (G4) structure of the aptamer enhances the fluorescence emission of NMM (610 nm). Besides this, the peroxidase-like activity of G4/hemin DNAzyme offers the colorimetric detection of Hg2+. The formation of duplex with PMDNAzyme increases the catalytic activity. This novel biosensing probe quantitatively detected Hg2+ using both fluorimetry and colorimetry approaches with a low detection limit of 0.59 and 36.3 nM, respectively. It was also observed that the presence of interfering metal ions in case of real aqueous samples does not affect the performance of this novel biosensing probe. These findings confirm the considerable potential of the proposed biosensing probe to screen the concentration of Hg2+ in aquatic products.

Smartphone-assisted colorimetric sensor arrays based on nanozymes for high throughput identification of heavy metal ions in salmon

The rapid, precise, and high-throughput identification of multiple heavy metals ions holds immense importance in ensuring food safety and promoting public health. This study presents a novel smartphone-assisted colorimetric sensor array for the rapid and precise detection of multiple heavy metals ions. The sensor array is based on three signal recognition elements (AuPt@Fe-N-C, AuPt@N-C, and Fe-N-C) and the presence of different heavy metal ions affects the nanozymes-chromogenic substrate (TMB) catalytic color production, enabling the differentiation and quantification of various heavy metal ions. Combined with a smartphone-based RGB mode, the colorimetric sensor array can successfully identify five different heavy metal ions (Hg2+, Pb2+, Co2+, Cr6+, and Fe3+) as low as 0.5 μM and different ratios of binary and ternary mixed heavy metal ions in just 5 min. The sensor array successfully tested seawater and salmon samples with a total heavy metal content of 10 μM in the South China Sea (Haikou and Wenchang). Overall, this study highlights the potential of smartphone-assisted colorimetric sensor arrays for the rapid and precise detection of multiple heavy metal ions, which could significantly contribute to food safety and public health monitoring.

A unique near-infrared fluorescent probe based on dual-DNP binding sites for rapid monitoring of hydrogen sulfide in food samples and living cells

A new NIR fluorescent probe (DCIQ-2DNP), which combined the thiolysis of dinitrophenyl (DNP) ether and DNP-marked electron-deficient quaternary carbon, was reported for the first time for detection of H2S. The DCIQ-2DNP probe showed an NIR emission signal (740 nm), a large Stokes shift (128 nm), and rapid monitoring of hydrogen sulfide (within 60 s) in food samples and living cells.

A turn-on anthraquinone-derived colorimetric and fluorometric dual-mode probe for highly selective Hg2+ determination and bioimaging in living organisms

Mercury ion (Hg2+) is considered a harmful neurotoxin, and real-time monitoring of Hg2+ concentrations in environmental and biological samples is critical. Fluorescent probes are a rapidly emerging visualization tool owing to their simple design and good selectivity. Herein, a novel fluorescence (FL) probe 2-(4-((6-((quinolin-8-yloxy)methyl)pyridin-2-yl)methyl)piperazin-1-yl)anthracene-9,10-dione (QPPA) is designed using piperazine as a linker between the anthraquinone group, which serves as a fluorophore, and N4O as the Hg2+ ligand. The probe exhibits FL "turn-on" sensing of Hg2+ because the complex inhibits the photo-induced electron transfer (PET) process. Moreover, QPPA can overcome the invasion by other possible cations, resulting in a clear color change from orange to colorless with the addition Hg2+. The chelation of QPPA with Hg2+ in a 1:1 ratio. Subsequently, the theoretically determined binding sites of the ligand to Hg2+ are validated through 1H NMR titration. The in situQPPA-Hg2+ complex can be subjected to Hg2+ extraction following the introduction of S2- owing to its robust binding capacity. The exceptional limit of detection values for Hg2+ and S2- are obtained as 63.0 and 79.1 nM (S/N = 3), respectively. Moreover, QPPA can display bright red FL in the presence of Hg2+ in different biological specimens such as HeLa cells, zebrafish, onion root tip tissues, and water flea Daphnia carinata, further providing an effective strategy for environmental monitoring and bioimaging of Hg2+ in living organisms.

A "Turn-On" Fluorescent Probe for the Visual Detection of Total Iron in Wine

A turn-on fluorescent sensor (E)-4-((4-(5-fluoro-1H-benzo[d]imidazol-2-yl)benzylidene)amino)phenol (FBAP) for the detection of Fe3+/2+ was synthesized. The fluorescence intensity of probe FBAP solution gradually increased with increased Fe3+ concentration. The low detection limit (LOD) was calculated to be 0.17 nM. The optimized structure and luminescent properties of FBAP were calculated by time-dependent density functional theory (TD-DFT) and Solvation Model Density (SMD). The rotation of the dihedral angle and ICT in the imine probe turned off the emission of the benzimidazole, which was restored upon cleaving the imine. Probe FBAP was successfully applied to determine whether Fe3+/2+ in wine exceeded the standard by phone and the rapid detection of Fe3+/2+ in the form of test strips was also conducted.

A highly sensitive and selective fluorescent "on-off-on" peptide-based probe for sequential detection of Hg2+ and S2- ions: Applications in living cells and zebrafish imaging

Mercury ions (Hg2+) and sulfur ions (S2-), have caused serious harm to the ecological environment and human health as two kinds of highly toxic pollutants widely used. Therefore, the visual quantitative determination of Hg2+ and S2- is of great significance in the field of environmental monitoring and medical therapy. In this study, a novel fluorescent "on-off-on" peptide-based probe DNC was designed and synthesized using dipeptide (Asn-Cys-NH2) as the raw material via solid phase peptide synthesis (SPPS) technology with Fmoc chemistry. DNC displayed high selectivity in the recognition of Hg2+, and formed non-fluorescence complex (DNC-Hg2+) through 2:1 binding mode. Notably, DNC-Hg2+ complex generated in situ was used as relay response probe for highly selective sequential detection of S2- through reversible formation-separation. DNC achieved highly sensitive detection of Hg2+ and S2- with the detection limits (LODs) of 8.4 nM and 5.5 nM, respectively. Meanwhile, DNC demonstrated feasibility for Hg2+ and S2- detections in two water samples, and the considerable recovery rate was obtained. More importantly, DNC showed excellent water solubility and low toxicity, and was successfully used for consecutive discerning Hg2+ and S2- in test strips, living cells and zebrafish larvae. As an effective visual analysis method in the field, smartphone RGB Color Picker APP realized semi-quantitative detections of Hg2+ and S2- without the need for complicated device.

A novel peptide fluorescent chemical sensor capable of detecting Cu2+, Zn2+, and S2

A novel peptide-based chemical fluorescence sensor L (Dansyl-His-Pro-Thr-Cys-NH2) was designed and synthesized. This sensor exhibits an "On-Off-On" detection cycle to detect Cu2+, Zn2+, and S2- in solution. According to the chelation-enhanced fluorescence (CHEF) mechanism, when Zn2+ is present, the fluorescence is significantly enhanced and a blue shift occurs, representing a "Turn-On" phase of the fluorescence detection mode. Because copper ions (Cu2+) have a paramagnetic quenching sensing mechanism, the fluorescence of L quenches rapidly with the formation of the L-Cu system, representing the "Turn-Off" phase. The subsequent introduction of S2- to the L-Cu system results in the recovery of the L-fluorescence, thereby representing the second "Turn-On" phase. As a peptide molecule, the sensor L has several advantages over other types of sensors, including water solubility, high sensitivity, and good biocompatibility, with a very low detection limit. The detection lines of Zn2+ and Cu2+ are 97 nM (R = 0.993) and 75 nM (R = 0.995), respectively. Additionally, the sensor does not exhibit any obvious cell toxicity. These results indicate that this peptide chemiluminescent sensor has the potential to be applied in in vivo detection.

Highly Sensitive Detection of Sulfur Ion in Water by Four-Color Fluorescence Based on Cu-Containing Metal-Organic Framework

In this paper, a highly sensitive method for sulfur ion (S2-) detection was developed based on a four-color fluorescence probe constructed from copper-containing metal-organic framework (CuBDC) and four dye-labeled single-strand DNA (ssDNA). In the absence of S2-, dye-labeled ssDNA can be adsorbed on the surface of CuBDC, and the dyes are close to copper ion on the CuBDC surface, their fluorescence is quenched by copper ion, and their fluorescence signals are weak. In the presence of S2- in the system, S2- reacts with copper ion in CuBDC to form CuS, which has a more stable structure than complex CuBDC, resulting in the decomposition of CuBDC. In this case, dye-labeled ssDNA are detached from the CuBDC surface and dissolved in the solution, and the fluorescence of the dyes is restored. Under the optimized conditions, there is a good linear relationship between the total fluorescence intensity of four dyes and the concentration of S2- in the range of 2 × 10-9 to 5 × 10-8 mol/L; the detection limit is 2.2 × 10-10 mol/L. The method has a good selectivity and accuracy, and it can be applied to the analysis and detection of S2- in actual water samples.

A dual-signals fluorometric and colorimetric peptide-based probe for Cu(II) and glyphosate detection and its application for bioimaging and water testing

A novel dual-signal fluorometric and colorimetric probe FMDH (5-FAM-Met-Asp-His-NH2), incorporating a tripeptide (Met-Asp-His-NH2) linked to 5-carboxyfluorescein (5-FAM), was firstly synthesised. FMDH demonstrated exceptional selectivity and sensitivity, rapid response, wide pH response range and robust anti-interference capabilities for monitoring Cu2+. This was achieved through a distinctive naked-eye colorimetric and fluorescent quenching behaviour. A good linearity within the range of 0-3 μM (R2 = 0.9914) was attained, and the limit of detection (LOD) for Cu2+ was 47.4 nM. Furthermore, the FMDH-Cu2+ ensemble responded to glyphosate with notable selectivity and sensitivity. A good linear correlation (R2 = 0.9926) was observed at the lower concentration range (2.4-7.8 μM) and achieving a detection limit as low as 29.9 nM. The response time of FMDH with Cu2+ and glyphosate were less than 20 s, and the pH range of 7-11 that was suitable for practical application under physiological pH conditions. MTT assays confirmed that FMDH offers good permeability and low toxicity, facilitating successful application in imaging analysis of Cu2+ and glyphosate in living cells and zebrafish. In addition, FMDH was employed in the detection of these analytes in real water samples. Cost-effective, highly sensitive and easily prepared FMDH-impregnated test strips were developed for the efficient visual detection of Cu2+ and glyphosate under 365 nm UV light. Increasing concentrations of Cu2+ and glyphosate resulted in notable colour changes under 365 nm UV light, enabling visual semi-quantitative analysis via a smartphone colour-analysis App.

A novel "Turn-Off-On" fluorescent probe for specific sequential detection of Cu2+ and glyphosate and its application in biological imaging

As common pollutants, Cu2+ and glyphosate pose a serious threat to human health and the ecosystem. Herein, a fluorescent probe (E)-7-(diethylamino)-N'(4-(diethylamino)-2-hydroxybenzyl)-2-oxo-2H chromophore-3-carbazide (DDHC) was designed and synthesised for the sequential recognition of Cu2+ and glyphosate. DDHC has the advantages of a short synthesis path, easy-to-obtain raw materials, good anti-interference ability, and strong stability. The interaction of the DDHC-Cu2+ complexes with glyphosate allows the amino and carboxyl groups in glyphosate molecules to coordinate with Cu2+ strongly, competing for the Cu2+ in the DDHC-Cu2+ complexes and releasing the DDHC, leading to the recovery of fluorescence. The recognition was further validated through Job's plot, HRMS, and DFT calculations. In addition, the successful recovery of Cu2+ and glyphosate in different environmental water samples fully demonstrates the practical application potential of DDHC. Especially, DDHC has low cytotoxicity and can enter zebrafish and HeLa cells, rapidly reacting with Cu2+ and glyphosate in the body, generating visible fluorescence quenching and recovery phenomena, achieving real-time visual monitoring of exogenous Cu2+ and glyphosate in zebrafish and HeLa cells. The targeting and dual selectivity of DDHC greatly enhance its potential application value in the field of detection, providing important theoretical support for studying the fate of multiple pollutants in the environment.

Rational design of peptide-based fluorescent probe for sequential recognitions of Cu(II) ions and glyphosate: Smartphone, test strip, real sample and living cells applications

A new peptide-based fluorescent probe named DMDH with easy-to-synthesize, excellent stability, good water solubility and large Stokes shift (225 nm) was synthesized for highly selective sequential detections of copper ions (Cu2+) and glyphosate (Glyp). DMDH demonstrated great detection performance towards Cu2+via strong fluorescence quenching, and forming non-fluorescence DMDH-Cu2+ ensemble. As a new promising cascade probe, the fluorescence of DMDH-Cu2+ ensemble was significantly recovered based on displacement approach after glyphosate was added. Interestingly, the limit of detections (LODs) for Cu2+ and glyphosate were 40.6 nM and 10.6 nM, respectively, which were far lower than those recommended by the WHO guidelines for drinking water. More importantly, DMDH was utilized to evaluate Cu2+ and glyphosate content in three real water samples, demonstrating that its effectiveness in water quality monitoring. Additionally, it is worth noting that DMDH was also applied to analyze Cu2+ and glyphosate in living cells in view of significant cells permeability and low cytotoxicity. Moreover, DMDH soaked in filter paper was used to create qualitative test strips and visually identify Cu2+ and glyphosate through significant color changes. Furthermore, smartphone RGB color recognition provided a new method for semi-quantitative testing of Cu2+ and glyphosate in the absence of expensive instruments.

Semi-quantitative and visual detection of Cu2+ and glyphosate in real samples and living cells using fluorescent and colorimetric dual-signals peptide-based probe

The excessive emission of copper ions (Cu2+) and the abuse of glyphosate (Glyp) have caused serious harm to the ecological environment and human health, so it is important to develop a fast and convenient method for the analysis of Cu2+ and glyphosate to ensure environmental and food safety. Herein, a dual-signals peptide-based probe (FASRH) with fluorescent and colorimetric was prepared using 5-carboxyl fluorescein modified tetrapeptide (Ala-Ser-Arg-His-NH2). FASRH was successfully used to recognize Cu2+ as a fluorescence "on-off" probe, forming the FASRH-Cu2+ complex with non-fluorescence. As a new promising cascade probe, FASRH-Cu2+ complex probe has high selectivity (only Glyp), good sensitivity (50.2 nM), good anti-interference ability and wide pH range (7.0-11.0) for the detection of glyphosate by ligand replacement method. In addition, the recognizable color changed markedly under 365 nm UV light and natural light. Notably, FASRH not only achieved accurate monitoring of Cu2+ and glyphosate in two real water samples, but also successfully applied to detect Cu2+ and glyphosate in live Hacat cells based on low cytotoxicity. Moreover, it is worth noting that FASRH-impregnated test strips exhibited significant fluorescence and colorimetric color changes for Cu2+ and glyphosate via naked eye. Furthermore, smartphone-assisted FASRH was used for the portable detection of Cu2+ and glyphosate based on the advantages of simplicity, low cost and fast response.

A sensitive benzothiazole fluorescent probe for the detection of γ-glutamyl transpeptidase activity and its application

A sensitive benzothiazole fluorescent probe (PBZO) for the detection of γ-glutamyl transpeptidase (GGT) activity was developed. Based on the enzymatic hydrolysis of peptide bonds by glutamyl transpeptidase, it can be specifically recognized by PBZO. The PBZO has a good linear relationship with different gradients of GGT activity at the emission wavelength of 560 nm, the Stokes shift reached 215 nm, and the detection limit of GGT activity is 0.1644 U/ml. With the increase of GGT concentration in the probe solution, the color of the solution gradually changed from orange to dark yellow under the 365 nm UV lamp. The same color change was also observed on the probe test paper. In addition, there is a linear relationship between the GGT activity and the R-value of the probe solution. More importantly, the probe has a good recovery rate in serum. Therefore, this probe can be used as a convenient tool for detecting GGT activity.

Ratiometric peptide-based fluorescent probe with large Stokes shift for detection of Hg2+ and S2- and its applications in cells imaging and smartphone-assisted recognition

In this work, a new ratiometric fluorescent probe DKA was synthesized based on the double sides of lysine backbone conjugated with alanine and dansyl groups. DKA exhibited fluorescence ratiometric response for Hg2+ with high sensitivity (13.4 nM), specific selectivity (only Hg2+), strong anti-interference ability (no interference), fast recognition (within 60 s) and wide pH range (5-10). The stoichiometry of binding of DKA and Hg2+ was determined to be 1:1 via Job's plot, ESI-HRMS and 1HNMR titration analysis. Subsequently, the in situ formation of DKA-Hg2+ complex was used for highly selective detection of S2- as a novel fluorescence "on-off" probe, and the lowest detection limit for S2- was 12.9 nM. In addition, DKA possessed excellent cells permeation and low toxicity, and fluorescence imaging of Hg2+ and S2- was performed in living Hacat cells. Most importantly, the digital imaging using a smartphone color recognition APP indicated that DKA could semi-quantitatively and visually detected Hg2+ and S2- without expensive equipment.

Urine Test Strip Quantitative Assay with a Smartphone Camera

Urine test strips for urinalysis are a common diagnostic tool with minimal costs and are used in various situations including homecare and hospitalization. The coloration scaled by the naked eye is simple, but it is suitable for semiquantitative analysis only. In this paper, a colorimetric assay is developed based on a smartphone digital camera and urine test strips. Assays of pH, albumin, glucose, and lipase activity were performed as a tool for the diagnosis of aciduria, alkaluria, glycosuria, proteinuria, and leukocyturia. The RGB color channels were analyzed in the colorimetric assay, and the assay exerted good sensitivity, and all the particular diagnoses proved to be reliable. The limits of detection for glucose (0.11 mmol/L), albumin (0.15 g/L), and lipase (2.50 U/μL) were low enough to cover the expected physiological concentration, and the range for pH was also satisfactory. The urine test strips with a camera as an output detector proved applicability to spiked urine samples, and the results were also well in comparison to the standard assays which confirms the practical relevance of the presented findings.