Blue emitting copper nanoclusters as colorimetric and fluorescent probe for the selective detection of bilirubin

Yellow Emissive Carbon Dots - A Robust Nanoprobe for Highly Sensitive Quantification of Jaundice Biomarker and Mitochondria Targeting in Cancer Cells

The abnormally high level of bilirubin (BR) in biofluids (human serum and urine) indicates a high probability of jaundice and liver dysfunction. However, quantification of BR as the Jaundice biomarker is difficult due to the interference of various biomolecules in serum and urine. To address this issue, we developed a fluorescence-based detection strategy, for which yellow emissive carbon dots (YCDs) were produced from a one-step solvothermal process using phloroglucinol and thionin acetate as chemical precursors. The as-fabricated YCDs exhibited a strong fluorescence peak at the wavelength of 542 nm upon excitation at 390 nm. We used YCDs for detecting BR through the fluorescence turn-off mechanism, unveiling the excellent sensitivity in the linear range of 0.5-12.5 μM with a limit of detection (LOD) of 9.62 nM, which was far below the clinically relevant range. The analytical nanoprobe also offered excellent detection specificity for quantifying BR in real samples. Moreover, the biocompatible fluorescent nanoprobe was successfully employed to target mitochondria in live cancer cells. A colocalization study confirmed that YCDs possessed the ability to target mitochondria and overlapped completely with MitoTracker Red. The developed nanoprobe of YCDs turned out to be straightforward in their synthesis, noninvasive, and can be utilized for biomedical sensors to diagnose the onset of jaundice as well as for mitochondria targeting.

Biosynthesis of copper nanoclusters for fluorescence detection of bilirubin in biofluids

Copper nanoclusters (Cu NCs) have shown significant attention in sensing of molecular and ionic species. In this work, a single-step biosynthetic approach was introduced for the preparation of fluorescent Cu NCs using Holarrhena pubescens (H. pubescens) leaves extract as a template. The synthesized H. pubescens-Cu NCs act as a nanomolecular probe for the detection of bilirubin in biofluids. The synthesized H. pubescens-Cu NCs displayed highest fluorescence intensity at 454 nm, when excited at 330 nm. Importantly, selective detection of bilirubin was obtained by introducing H. pubescens-Cu NCs as a simple molecular probe. The interaction of bilirubin and H. pubescens-Cu NCs resulted in a remarkable decrease in the emission peak intensity. The developed H. pubescens-Cu NCs-based bilirubin molecular probe has a wide linear range of 0.5-20.00 μM with the limit of detection of 30.54 nM for bilirubin. The promising application of H. pubescens-Cu NCs-based molecular probe was assessed by assaying bilirubin in spiked biofluids.

Analytical developments in the synergism of copper particles and cysteine: a review

Cysteine, a sulfur-containing amino acid, is a vital candidate for physiology. Coinage metal particles (both clusters and nanoparticles) are highly interesting for their spectacular plasmonic properties. In this case, copper is the most important candidate for its cost-effectiveness and abundance. However, rapid oxidation destroys the stability of copper particles, warranting the necessity of suitable capping agents and experimental conditions. Cysteine can efficiently carry out such a role. On the contrary, cysteine sensing is a vital step for biomedical science. This review article is based on a comparative account of copper particles with cysteine passivation and copper particles for cysteine sensing. For the deep understanding of readers, we discuss nanoparticles and nanoclusters, properties of cysteine, and importance of capping agents, along with various synthetic protocols and applications (sensing and bioimaging) of cysteine-capped copper particles (cysteine-capped copper nanoparticles and cysteine-capped copper nanoclusters). We also include copper nanoparticles and copper nanoclusters for cysteine sensing. As copper is a plasmonic material, fluorometric and colorimetric methods are mostly used for sensing. Real sample analysis for both copper particles with cysteine and copper particles for cysteine sensing are also incorporated in this review to demonstrate their practical applications. Both cysteine-capped copper particles and copper particles for cysteine sensing are the main essence of this review. The aspect of the synergism of copper and cysteine (unlike other amino acids) is quite promising for future researchers.

Fluorescent Nitrogen-doped Carbon Dots-based Turn-off Sensor for Bilirubin

Bilirubin (BR), a heme protein produced from breakdown of haemoglobin is present in aged red blood cells; whose abnormal concentration is associated with diseases like hyperbilirubinemia, coronary disease, iron deficiency, and so on. Herein, we have synthesized a selective, sensitive, and low-cost sensing platform using fluorescent nitrogen doped carbon dots (NCDs), prepared from precursors; citric acid and urea via a simple microwave-assisted method. The emission at 444 nm on excitation with 360 nm was well quenched in presence of BR suggesting a direct turn-off detection for BR. Characterization of developed probe was done by UV-Visible absorption studies, photoluminescence studies, SEM, TEM, ATR-FTIR, XPS, and DLS analysis. BR was detected with a Limit of Detection (LoD) and Limit of Quantification (LoQ) of 0.32 µM and 1.08 µM respectively. NCDs exhibited excellent selectivity and sensitivity towards BR in the presence of co-existing biomolecules and ions. Practical feasibility was checked by paper-strip-based sensing of BR and spiked real human samples were used for conducting real sample analysis.

Label-Free Detection of Unbound Bilirubin and Nitrophenol Explosives in Water by a Mechanosynthesized Dual Functional Zinc Complex: Recognition of Picric Acid in Various Common Organic Media

High levels of unconjugated bilirubin (UB) in serum lead to asymptomatic and neonatal jaundice and brain dysfunctions. Herein, we have reported the detection of UB at as low as 1 μM in an aqueous alkaline medium using a Zn(II) complex. The specificity of the complex has been validated by the HPLC in the concentration window 6-90 μM, which is rare. The sensory response of the probe at physiological pH against nitro explosives developed it as an instant-acting fluorosensor for picric acid (PA) and 2,4-dinitrophenol (2,4-DNP). Spectroscopic titration provided a binding constant of 4×105  M-1 with PA. The naked eye detection was found to be 15 μM. The solid-state photoluminescent nature of the complex enabled it for PA sensing in the solid phase. Interestingly, the probe remained fluorescent in various volatile and non-volatile organic solvents. As a result, it can also detect PA and 2,4-DNP in a wide range of common organic media. NMR studies revealed the coordination of PA, 2,4-DNP, and UB to the Zn(II) center of the probe, which is responsible for the observed quenching of the probe with the analytes.

Challenges and Opportunities of Using Fluorescent Metal Nanocluster-Based Colorimetric Assays in Medicine

Development of rapid colorimetric methods based on novel optical-active metal nanomaterials has provided methods for the detection of ions, biomarkers, cancers, etc. Fluorescent metal nanoclusters (FMNCs) have gained a lot of attention due to their unique physical, chemical, and optical properties providing numerous applications from rapid and sensitive detection to cellular imaging. However, because of very small color changes, their colorimetric applications for developing rapid tests based on the naked eye or simple UV-vis absorption spectrophotometry are still limited. FMNCs with peroxidase-like activity have significant potential in a wide variety of applications, especially for point-of-care diagnostics. In this review, the effect of using various capping agents and metals for the preparation of nanoclusters in their colorimetric sensing properties is explored, and the synthesis and detection mechanisms and the recent advances in their application for ultrasensitive chemical and biological analysis regarding human health are highlighted. Finally, the challenges that remain as well as the future perspectives are briefly discussed. Overcoming these limitations will allow us to expand the nanocluster's application for colorimetric diagnostic purposes in medical practice.

Spectral analysis with highly collimated mini-LEDs as light sources for quantitative detection of direct bilirubin

Because the human eye cannot visually detect the results of direct bilirubin test papers accurately and quantitatively, this study proposes four different highly collimated mini light-emitting diodes (HC mini-LEDs) as light sources for detection. First, different concentrations of bilirubin were oxidized to biliverdin by FeCl3 on the test paper, and pictures were obtained with a smartphone. Next, the red, green, and blue (RGB) channels of the pictures were separated to average grayscale values, and their linear relationship with the direct bilirubin concentration was analyzed to detect bilirubin on the test paper noninvasively and quantitatively. The experimental results showed that when green HC mini-LEDs were used as the light sources and image analysis was performed using the G channel, for a direct bilirubin concentration range of 0.1-2 mg/dL, the G channel determination coefficient (R2) reached 0.9523 and limit of detection was 0.459 mg/dL. The detection method proposed herein has advantages such as rapid analysis, noninvasive detection, and digitization according to RGB grayscale changes in the images of the detection test paper.

Towards Green Synthesis of Fluorescent Metal Nanoclusters

In the modern development of nanoscience and nanotechnology, metal nanoclusters have emerged as a foremost category of nanomaterials exhibiting remarkable biocompatibility and photo-stability having dramatically distinctive optical, electronic, and chemical properties. This review focuses on synthesizing fluorescent metal nanoclusters in a greener way to make them suitable for biological imaging and drug delivery application. The green methodology is the desired route for sustainable chemical production and should be utilized for any form of chemical synthesis including nanomaterials. It aims to eliminate harmful waste, uses non-toxic solvents, and employs energy-efficient processes for the synthesis. This article provides an overview of conventional synthesis methods, including stabilizing nanoclusters by small organic molecules in organic solvents. Then we focus on the improvement of properties, applications of green synthesized metal nanoclusters, challenges involved, and further advancement required in the direction of green synthesis of MNCs. There are plenty of problems for scientists to solve to make nanoclusters suitable for bio-applications, chemical sensing, and catalysis synthesized by green methods. Using bio-compatible and electron-rich ligands, understanding ligand-metal interfacial interactions, employing more energy-efficient processes, and utilizing bio-inspired templates for synthesis are some immediate problems worth solving in this field that requires continued efforts and interdisciplinary knowledge and collaboration.

Nucleic acid aptamer-based biosensors and their application in thrombin analysis

Thrombin is a multifunctional serine protease that plays an important role in coagulation and anticoagulation processes. Aptamers have been widely applied in biosensors due to their high specificity, low cost and good biocompatibility. This review summarizes recent advances in thrombin quantification using aptamer-based biosensors. The primary focus is optical sensors and electrochemical sensors, along with their applications in thrombin analysis and disease diagnosis.

Nanomaterials for fluorescent assay of bilirubin

The accumulation of bilirubin in blood is associated with many diseases. Sensitive and accurate detection of bilirubin is of great significance for personal health care. The rapid development of fluorescent nanomaterials promotes rapid development in the bilirubin assay. In this review, traditional methods for detection of bilirubin are briefly presented to compare with fluorescent nanosensors. Subsequently, the recent progress of different types of fluorescent nanomaterials for determination of bilirubin is summarized. Further, the performance of fluorescent nanosensors and conventional techniques for sensing bilirubin are compared. To this end, the challenges and prospects concerning the topics are discussed. This review will provide some introductory knowledge for researchers to understand the status and importance of fluorescent nanosensors for sensing bilirubin.

A paper-based point-of-care testing device for the colourimetric estimation of bilirubin in blood sample

A paper-based colourimetric assay for the Point-of-Care Testing (PoCT) of bilirubin has been developed based on the formation of a green-coloured copper-bilirubin complex from a blue-coloured tetraamminecopper(II) sulphate complex. The reaction was studied and optimized by UV-Visible absorption spectroscopy and translated onto a paper strip. Hydrophobic circular well patterns on Whatman chromatography paper were created by wax printing. The tetraamminecopper(II) sulphate complex was drop cast and dried on the reagent zones in the wax-patterned paper. The images of reagent zones captured using a scanner were analyzed using ImageJ software. Bilirubin spiked blood serum was tested in the concentration range of 1.2 to 950 µM. The PAD exhibited sensitivities of 0.4197 a.u/μM and 0.1040 a.u/μM for concentration ranges of bilirubin 1.2 to 96 μM and 105 to 950 μM respectively and a low detection limit of 0.799 µM. The method is highly selective to bilirubin, even in the presence of other biomarkers in serum. A plasma separation membrane incorporated PAD was fabricated for the final testing and quantification of bilirubin from whole blood.

Expeditious fluorimetric detection of bilirubin by simple imidazole derived luminophore and it's pragmatic applicability in spiked biological fluids

Bilirubin is an indispensable biomarker for liver diseases. Utilizing organic molecules as sensor platform for effective detection of bilirubin are little. In addition, the reported fluorophores required longer incubation time for detection. Hence, herein we have attempted to design an imidazole derivative 4-(3H-imidazo[4,5-b]pyridin-2-yl)-N,N-diphenylaniline (IMI) from triphenylamine and pyridine units which could detect bilirubin swiftly without any incubation period. IMI manifested an instant quenching of emission in presence of bilirubin with limit of detection (LOD) 11.74 × 10^-6 mol L^-1. The mechanistic aspect of detection involves coexistence of both static and dynamic quenching which was suitably justified. Finally, the pragmatic application of IMI was performed in bio-fluids.

A highly selective fluorescent sensor for chlortetracycline based on histidine-templated copper nanoclusters

In this study, histidine-protected copper nanoclusters (Cu NCs@His) were established by using a one-pot method, which histidine and ascorbic acid were applied as the template and reducing agent, respectively. The as-developed Cu NCs@His endued green emission wavelength at 494 nm with the excitation of 378 nm. The Cu NCs@His exhibited green fluorescence under UV light (365 nm). Using Cu NCs@His as a pattern nanosensor, the fluorescent "turn off" mechanism was fabricated for the determination of chlortetracycline in the light of the linear decrease of fluorescence intensities around 494 nm. The chlortetracycline conducted as a quencher, leading to reveal an excellent linear relationship between ln(F₀/F) of Cu NCs@His and chlortetracycline concentrations with the range of 0.5-200 μM, and the detection limit was 0.876 μM. The fluorescence quenching of Cu NCs@His revealed excellent selectivity for chlortetracycline over other potential interfering substances in the human body. This strategy was exhibited to be a convenient sensing platform for the detection of chlortetracycline in real medical samples, which could unfold a brand new and direct system for the sensing of chlortetracycline in real samples.

Ratiometric fluorescence and visual determination of tetracycline antibiotics based on Y3+ and copper nanoclusters-induced cascade signal amplification

A ratiometric fluorescence probe is proposed for sensitive and visual detection of tetracyclinee (TC) based on cascade fluorescence signal amplification induced by bovine serum albumin-stabilized copper nanoclusters (BSA-CuNCs) and yttrium ions (Y³⁺). TC can combine with Y³⁺ to form the complex (TC-Y³⁺) to enhance the fluorescence of TC at 515 nm. Then, positively charged TC-Y³⁺ and negatively charged BSA-CuNCs was bonded together by electrostatic interactions to achieve the fluorescence resonance energy transfer (FRET) process. With the increase of TC concentration, the fluorescence intensity of TC-Y³⁺ at 515 nm (F₅₁₅) gradually increased; meanwhile, the fluorescence intensity of BSA-CuNCs at 405 nm (F₄₀₅) decreased gradually. The ratio of F₅₁₅ and F₄₀₅ was used for the quantitative determination of TC. The linear range of the constructed fluorescent probe is 1.0 to 60.0 μM, and the limit of detection is 0.22 μM. The method was successfully applied to the determination of TC in spiked milk with recoveries ranging from 94.3 to 112%. Furthermore, the color of this platform can be observed from dark violet to bright green under the UV lamp. Since the response time of the reaction is less than 10 s, an intelligent sensing platform based on the use of the smartphone as image acquisition equipment was also established to realize rapid on-site and portable detection of TC through the colorimetric recognition application.

Recent advances in nanomaterials-based optical sensors for detection of various biomarkers (inorganic species, organic and biomolecules)

This review briefly emphasizes the different detection approaches (electrochemical sensors, chemiluminescence, surface-enhanced Raman scattering), functional nanostructure materials (quantum dots, metal nanoparticles, metal nanoclusters, magnetic nanomaterials, metal oxide nanoparticles, polymer-based nanomaterials, and carbonaceous nanomaterials) and detection mechanisms. Further, this review emphasis on the integration of functional nanomaterials with optical spectroscopic techniques for the identification of various biomarkers (nucleic acids, glucose, uric acid, oxytocin, dopamine, ascorbic acid, bilirubin, spermine, serotonin, thiocyanate, Pb²⁺ , Cu²⁺ , Hg²⁺ , F^- , peptides, and cancer biomarkers (mucin 1, prostate specific antigen, carcinoembryonic antigen, CA15-3, human epidermal growth factor receptor 2, C-reactive protein, and interleukin-6). Analytical characteristics of nanomaterials-based optical sensors are summarized in Tables, providing the insights of nanomaterials-based optical sensors for biomarkers detection. Finally, the opportunities and challenges of nanomaterials-based optical analytical approaches for the detection of various biomarkers (inorganic, organic, biomolecules, peptides and proteins) are discussed.

A deoxygenation-switch-based red-emitting fluorogenic light-up probe for the detection of highly toxic free bilirubin in human blood serum

Reaction-based chemical switches are attracting great interest due to their high selectivity, and their use has become a powerful technique for developing fluorogenic probes. Herein, a benzorhodol-derivative-attached N-oxide probe (DEBNox) has been designed as a new fluorogenic probe for the detection of the biologically toxic species bilirubin based on a deoxygenation switching mechanism. Upon reaction with added Fe³⁺, bilirubin produces Fe²⁺ ions in situ, which in turn promote a deoxygenation reaction with DEBNox to generate the corresponding high-red-fluorescence (λ_em: ∼623 nm) benzorhodol derivative (DEB). This type of Fe³⁺-mediated response helps the probe to act as a qualified turn on selective fluorescence sensor for bilirubin with a detection range as low as 33 nM. Moreover, the probe was successfully employed to detect free bilirubin in human blood serum specimens with acceptable accuracy and reliability. This DEBNox-based light-up strategy also facilitates the construction of reliable and highly sensitive assays based on a paper-based strategy, similar to pH-indicator paper, as is demonstrated here via bilirubin detection in real serum samples. These findings could be useful for developing powerful diagnostic tools for the detection of free bilirubin in the near further.

Copper nanoclusters: designed synthesis, structural diversity, and multiplatform applications

Atomically precise metal nanoclusters (MNCs) have gained tremendous research interest in recent years due to their extraordinary properties. The molecular-like properties that originate from the quantized electronic states provide novel opportunities for the construction of unique nanomaterials possessing rich molecular-like absorption, luminescence, and magnetic properties. The field of monolayer-protected metal nanoclusters, especially copper, with well-defined molecular structures and compositions, is relatively new, about two to three decades old. Nevertheless, the massive progress in the field illustrates the importance of such nanoobjects as promising materials for various applications. In this respect, nanocluster-based catalysts have become very popular, showing high efficiencies and activities for the catalytic conversion of chemical compounds. Biomedical applications of clusters are an active research field aimed at finding better fluorescent contrast agents, therapeutic pharmaceuticals for the treatment and prevention of diseases, the early diagnosis of cancers and other potent diseases, especially at early stages. A huge library of structures and the compositions of copper nanoclusters (CuNCs) with atomic precisions have already been discovered during last few decades; however, there are many concerns to be addressed and questions to be answered. Hopefully, in future, with the combined efforts of material scientists, inorganic chemists, and computational scientists, a thorough understanding of the unique molecular-like properties of metal nanoclusters will be achieved. This, on the other hand, will allow the interdisciplinary researchers to design novel catalysts, biosensors, or therapeutic agents using highly structured, atomically precise, and stable CuNCs. Thus, we hope this review will guide the reader through the field of CuNCs, while discussing the main achievements and improvements, along with challenges and drawbacks that one needs to face and overcome.

Blue-emitting glutathione-capped copper nanoclusters as fluorescent probes for the highly specific biosensing of furazolidone

Herein, a facile, straightforward and green method was developed to prepare copper nanoclusters by using glutathione (GSH) as the protecting agent and ascorbic acid as the reducing agent. The glutathione-templated copper nanoclusters (GSH-Cu NCs) were characterized through fluorescence spectroscopy, UV-vis absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and fluorescence lifetime analysis. The as-synthesized Cu NCs showed blue fluorescence with a peak centered at 426 nm. The Cu NCs had excellent water solubility, stability and dispersibility. Based on the inner filter effect and static quenching mechanism, Cu NCs were employed to detect furazolidone in bovine serum samples. Under optimal detection conditions, a good linear relationship was observed between F₀/F and the furazolidone concentration from 0.05 to 60 μM. The detection limit (LOD) was 0.012 μM. Furthermore, the fluorescence probe was successfully used in the quantification of furazolidone in bovine serum samples. In addition, this analytical method provides a rapid, easy and ultrasensitive fluorescence platform for the detection of furazolidone.

Aggregation-induced emission enhancement of gold nanoclusters in metal-organic frameworks for highly sensitive fluorescent detection of bilirubin

A fluorescence analysis method based on gold nanocluster (AuNC) and metal-organic framework (MOF) composite materials (AuNCs@ZIF-8) was established for highly sensitive detection of bilirubin (BR). First, AuNCs@ZIF-8 was successfully obtained by co-precipitation and displayed an aggregation-induced emission enhancement by the confinement effect of the MOFs (i.e., ZIF-8). The product showed approximately 7.0 times enhancement in the quantum yield and longer fluorescence lifetime from 2.29 μs to 11.51 μs compared with AuNCs. When BR combined with the metal node Zn2+ of ZIF-8, the skeleton of the composite was destroyed, leading to a great decrease in the fluorescence intensity by the transformation of the AuNCs from the aggregated state to dispersed state. The linear range for the detection of BR was 0.1-5.0 μM, with the limit of detection (LOD) of 0.07 μM (S/N = 3). The AuNCs@ZIF-8 exhibited a selective response toward BR within 5 min and detected BR in human serum. The long-wavelength emission by AuNCs avoided the interference of the complex biomatrix background fluorescence, indicating their great application prospects for clinical diagnosis.

A selective and sensitive fluorescent probe for bilirubin in human serum based on europium(III) post-functionalized Zr(IV)-Based MOFs

In the present study, a kind of Eu(III) post-functionalized Zr(IV)-based metal-organic framework (UiO-66(COOH)₂, Zr-MOF: Eu³⁺) was synthesized and utilized as an independently luminescent probe for sensing bilirubin (BR) in human serum, a biomarker of jaundice hepatitis. It can be served as a turn-off fluorescent switch for BR because its red emission from Eu³⁺ can be easily quenched by BR through a fluorescent resonant energy transfer (FRET) process between BR and its ligands, and as a result, BR is recognized successfully. Particularly, Zr-MOF: Eu³⁺ has shown many appealing properties, such as high sensitivity, quick response (less than 1 min), broad response window (0-15 μM), and excellent selectivity. Most importantly, a kind of portable test paper based on Zr-MOF: Eu³⁺ probe has been developed for directly assessing the level of BR in real human serum and further diagnosing bilirubin-related diseases via visually observing the luminescent color variation.

A Simple and Cost Effective Turn off Fluorescence Sensor for Biliverdin and Bilirubin Based on L-Cysteine Modulated Copper Nanoclusters

The present article reports the efficiency of L-cysteine modulated copper nanoclusters (L-cys-CuNCs) as a fluorescent probe for the selective determination of naturally occurring bile pigments biliverdin (BVD) and bilirubin (BLR). These pigments were found to quench the fluorescence of L-cys-CuNCs through static processes. Under optimized conditions, the proposed strategy permitted the quantification of BVD and BLR in the range 4.00 × 10^-5 to 5.00 × 10^-7M and 1.00×10^-5 to 1.00×10^-6 M respectively with limits of detection 2.33 × 10^-7M and 2.29 × 10^-7 M. The practical utility of the developed sensor have been investigated in spiked blood and urine samples.

Water-soluble MoS2 quantum dots as effective fluorescence probe for the determination of bilirubin in human fluids

Bilirubin is an important biomarker in the diagnosis and prognosis of patients with liver disorders. Herein, we report a simple, rapid, sensitive and selective quantitative determination of bilirubin using molybdenum disulfide quantum dots (MoS₂ QDs) as a probe. The MoS₂ QDs were synthesized through a hydrothermal route by using sodium molybdate and cysteine as the starting materials. The obtained MoS₂ QDs exhibits strong luminescence property and excellent stability. The HR-TEM image shows that the size of the prepared MoS₂ QDs was 2.4 nm with a spherical morphology. The MoS₂ QDs emit intense blue photoluminescence (with excitation/emission peaks at 310/392 nm) under UV light and the fluorescence of MoS₂ QDs was drastically quenched by the addition of bilirubin. The Förster resonance energy transfer (FRET) and inner filter effect (IFE) between MoS₂ QDs and bilirubin resulted in the fluorescence quenching of MoS₂ QDs. The present method demonstrated high sensitivity towards bilirubin with the limit of detection (LOD) of 2.1 nM (S/N = 3). The MoS₂ QDs probe showed remarkable selectivity to bilirubin over other possible interferences. Moreover, the present fluorophore was successfully utilized for the detection of bilirubin in human serum and urine samples. QDs based fluorescence probe for the recognition of bilirubin is reported for the first time.

Reversible fluorescence modulation of BSA stabilised copper nanoclusters for the selective detection of protamine and heparin

Depicting fluorescence sensing of protamine and heparin based on aggregation and disaggregation of copper nanoclusters.