Aniline blue test for sperm protamination-a valuable add-on to the bull breeding soundness evaluation.

Bull breeding soundness evaluation (BBSE) is the most common procedure used to predict bull potential fertility. However, the use of traditional methods for semen evaluation can affect its reliability. The inclusion of additional advanced test in BBSE may increase its accuracy. This study aimed to investigate the correlation between the degree of sperm protamination and BBSE main parameters of scrotal circumference (SC), progressive motility (PM), morphologically normal sperm (NS), and different categories of morphological defects. In addition, to determine the correlation between the three methods used for protamine assessment, five Brangus bulls were subjected to the BBSE. Semen samples were collected via electro-ejaculation and evaluated using traditional methods. Three different methods were used to determine the degree of sperm protamination: aniline blue (AB) staining, chromomycin A3 staining with fluorescent microscope (CMA3-FLM), and CMA3 with flow cytometry (CMA3-FCM). Sperm protamine deficiency assessed using the three methods exhibited significant differences among bulls according to their classification by BBSE, and showed significant negative correlation with semen quality parameters of NS and PM. A significant positive correlation was found between AB positivity and morphological abnormalities. The three methods used for protamine assessment also revealed significant positive correlations. Among the three tests, AB staining was the cheapest and easiest test that offers an objective assessment method for sperm protamination. Hence, it can be concluded that the assessment of protamination using AB staining test might serve as an additional valuable parameter or a replacement whenever detail sperm motility and morphology analyses in conducting BBSE to predict bull fertility are not possible.

Luminescence Sensing of Biomacromolecules Heparin and Protamine in 100% Human Serum and Plasma by Supramolecular Polymeric Assemblies.

Heparin, an anionic biomacromolecule, is routinely used as an anticoagulant during medical surgery to prevent blood clot formation and in the treatment of several heart, lung, and circulatory disorders having a higher risk of blood clotting. We herein report supramolecular polymeric nanoassemblies of cationic pyrene-tagged bis-imidazolium amphiphiles for heparin detection with high sensitivity and selectivity in aqueous buffer, plasma, and serum media. The nano-assemblies exhibited cyan-green excimeric emission in aqueous media, and their multivalent array of positive surface charges allowed them to form co-assemblies with heparin, resulting in significantly enhanced emission. This provided a convenient method for heparin detection in buffer at nanomolar concentrations, and most notably, a ratiometric fluorescence response was obtained even in highly competitive 100% human serum and 100% human plasma in a clinically relevant concentration range. Moreover, using the heparin-based luminescent co-assemblies, protamine sulfate, a clinically administered antidote to heparin, was also detected in 100% human serum and 100% human plasma at sub-micromolar concentrations.

Optical Detection of Heparin in Whole Blood Samples Using Nanosensors Embedded in an Agarose Hydrogel.

Point-of-care quantification of the anticoagulant heparin still remains a significant clinical challenge as the reference method (colorimetric anti-factor Xa assay) cannot be performed in whole blood. Our group recently put forth the novel optical nanosensing principle using an ionic solvatochromic dye as a signal transducer. These nanosensors demonstrated significantly improved selectivity and sensitivity compared to ion-exchange-type polyion nanosensors and enabled protamine/heparin quantification in blood plasma samples. However, because the readout is absorbance-based, they are still not suitable for whole blood measurements. To overcome the background absorbance of blood, the nanosensors were here embedded in an agarose hydrogel capable of filtering out red blood cells while allowing plasma components to diffuse into the gel. Calibration curves for both protamine and heparin were successfully obtained in buffer, undiluted plasma, and undiluted whole blood using different colorimetric image analysis methods and a simple experimental setup.

Thin membrane-based potentiometric sensors for sensitive detection of polyions.

A novel protocol for development of sensitive and rapid polymeric membrane polyion sensitive electrodes has been explored in this work. In contrast to the traditional polyion electrodes which usually have a sensing membrane thickness of 100∼200 µm, a thin membrane electrode with a membrane thickness of 5 µm is proposed to detect polyions. By using such thin membrane configuration, the diffusion of polyions from the organic boundary layer into the bulk of the membrane can be effectively blocked. The induced accumulation of polyions in the membrane boundary layer largely enhances the obtained potential response. It has been found that the proposed electrode shows a remarkably improved sensitivity and measurement time over conventional potentiometric polyion sensors based on the thick membranes. By using protamine as a model of polyions, the new concept offers a detection limit nearly two orders of magnitude lower than those obtained by the traditional thick-membrane polyion electrodes for potentiometric measurements of polyions. The proposed polyion sensing platform offers great promise in the sensitive and rapid detection of polyions as well as other polyion-involved bioanalyses.

Response Mechanism of Hyperpolarization-Based Polyion Nanosensors.

The last decade has witnessed a rapid development of nano- and microparticle-based optical ion sensors, including ion-selective optodes (ISOs). While the application of nano-ISOs has shown promising performance for sensing inorganic ions, polyion sensing using nanoscale ISOs has encountered significant interference in complex samples such as blood plasma. Recently, we have reported on a new polyion sensing principle that operates through a novel mechanism to overcome this challenge. The new sensing mechanism showed improved characteristics not observed with conventional ion-exchange type sensors, but the precise mechanism of operation remained thus far unclear. This paper aims to clarify how protamine, the arginine-rich target polycation, behaves during optical signal transduction to give dramatically improved selectivity. Based on thermodynamic data, sensor performance and ζ-potential analysis, two discrete phases of protamine extraction are identified. Initially, protamine extracts into the bulk nanosensor phase, a process that is concurrent with the optical signal change. This is then followed by protamine accumulation onto the nanosensor surface, which starts only upon saturation of the optical signal change. The data indicate that the improved selectivity is due to the inability of small ions to form a sufficiently strong interaction with an active sensing ingredient, DNNS-. Any exchange of one inorganic cation for another therefore remains optically silent, suppressing matrix effects. Moreover, the recognition of protamine is shown to be an exhaustive extraction process, making the response independent of the nature and concentration of the initial small cation in the nanosensor phase.

Molecular Alterations and Severe Abnormalities in Spermatozoa of Young Men Living in the "Valley of Sacco River" (Latium, Italy): A Preliminary Study.

The Valley of Sacco River (VSR) (Latium, Italy) is an area with large-scale industrial chemical production that has led over time to significant contamination of soil and groundwater with various industrial pollutants, such as organic pesticides, dioxins, organic solvents, heavy metals, and particularly, volatile organic compounds (VOCs). In the present study, we investigated the potential impact of VOCs on the spermatozoa of healthy young males living in the VSR, given the prevalent presence of several VOCs in the semen of these individuals. To accomplish this, spermiograms were conducted followed by molecular analyses to assess the content of sperm nuclear basic proteins (SNBPs) in addition to the protamine-histone ratio and DNA binding of these proteins. We found drastic alterations in the spermatozoa of these young males living in the VSR. Alterations were seen in sperm morphology, sperm motility, sperm count, and protamine/histone ratios, and included significant reductions in SNBP-DNA binding capacity. Our results provide preliminary indications of a possible correlation between the observed alterations and the presence of specific VOCs.

Proteomic and genetic dissection of testis-specific histone 2B in infertile men reveals its contribution to meiosis and sperm motility.

OBJECTIVE: To investigate testis-specific histone 2B (TSH2B) and its gene anomalies in infertile men. DESIGN: Case-control study. SETTING: Basic science laboratory. PATIENT(S): Fertile and infertile men. INTERVENTION(S): Not applicable. MAIN OUTCOME MEASURE(S): The histone and protamine status of sperm was studied by aniline blue and chromomycin A3 staining, respectively. Testis-specific histone 2B, total H2B, and phosphorylated TSH2B (pTSH2B) were estimated by Western blot analysis. The frequency of genetic polymorphisms and rare variants in H2BC1 was studied by Sanger sequencing. Phosphosites on TSH2B in sperm were identified by reverse-phase high-performance liquid chromatography purification of TSH2B followed by mass spectrometric analysis. RESULT(S): Aniline blue and chromomycin A3 staining revealed significantly higher histone retention and low protamine in sperm of infertile men. Sperm TSH2B and total H2B levels were significantly lower in oligozoospermic and oligoasthenozoospermic men (in both groups). The TSH2B levels were comparable in asthenozoospermic men; however, the pTSH2B level was significantly low. The H2BC1 gene sequencing identified 6 variants, of which 2 are rare variants (rs368672899 and rs544942090) and 4 (rs4711096, rs4712959, rs4712960 and rs4712961) are single nucleotide polymorphisms. Minor allele frequency of 5'-untranslated region variant rs4711096 was significantly lower in infertile men (OR = 0.65). The rare nonsynonymous variant, rs368672899, p.Ser5Pro was seen in 1 oligoasthenoteratozoospermic individual. Interestingly, mass spectrometric analysis identified a site on TSH2B to bear a phosphate group in the sperm of fertile men. CONCLUSION(S): Our study reveals a defect in the replacement of somatic histones with testis-specific variants in infertile men. Chromatin compaction positively correlates with sperm motility, which is suggestive of its utility in diagnostic semen analysis of infertile individuals. Our observations with TSH2B and its cognate gene in sperm of infertile men indicate an essential role for TSH2B in meiosis and its phosphorylation in sperm motility, respectively.

Ultrafine fluorene-pyridine oligoelectrolyte nanoparticles for supersensitive fluorescence sensing of heparin and protamine.

A new fluorene-pyridine oligoelectrolyte (OFP) is rationally proposed and readily synthesized via a simple one-pot Sonogashira approach. Hence, an unexpectedly small cationic oligomer nanosensor (i.e. OFPNPs, ∼ 1.2 nm in diameter) was conveniently fabricated owing to the enhanced flexibility endowed by the meta-substituted pyridyl unit. Inspiringly, this facile nanoplatform with low cytotoxicity favors the ultrasensitive fluorescence assay for heparin and protamine with a detection limit (LOD, S/N = 3) as low as 1.2 ng mL-1 and 0.5 ng mL-1, respectively, involving heparin-induced aggregation of OFPNPs through electrostatic interaction or competitive rebinding of protamine to heparin.

Is there any relationship between human sperm parameters and protamine deficiency in different groups of infertile men? / ¿Existe alguna relación entre los parámetros del esperma humano y la deficiencia de protamina en varios grupos de varones infértiles?

OBJECTIVE: Abnormality in Histone-Protamine replacements has been indicated to cause sperm DNA damage and infertility. The aim of the present study was to investigate the relationships between sperm parameters in oligospermia, asthenospermia, and teratospermia with protamine deficiency in infertile men. MATERIAL AND METHOD: In this case-control study, we had three experimental groups including oligospermia (n=100), asthenospermia (n=100), and teratospermia (n=100) as well as normospermia (n=100) as controls. Sperm analyses were performed according to the recommendations of the World Health Organization (WHO, 2010) and sperm chromatin quality was assessed using Chromomycin A3 (CMA3) staining for each sample. RESULTS: The comparison of the data between groups indicated that the percentage of spermatozoa with protamine deficiency was significantly different in patients with oligospermia, asthenospermia, and teratospermia when compared with control ones. However, there was no significant correlation between sperm nuclear protamine deficiency and their parameters of the men with teratospermia using CMA3 test. Regarding the oligospermia and asthenospermia semen samples, the findings showed the negative correlations between the sperm nuclear protamine deficiency and progressive motility as well as immobility (p < 0.001). CONCLUSION: The higher proportion of spermatozoa with abnormal chromatin packaging was observed in asthenospermic samples than those from other experimental groups as well as controls. It seems that normal morphology cannot have a valuable predictive value for good chromatin quality of spermatozoa, as much as normal motility characteristics, since samples with high mobility rates often have lower protamine deficiencies. The findings may provide a supportable promoting the future wider clinical application of chromatin/DNA integrity testing along with the semen analysis in male infertility

OBJETIVO: Se ha indicado que la irregularidad en los reemplazos de histona-protamina provoca daño en el ADN del esperma e infertilidad. El objetivo del presente estudio fue investigar las relaciones entre los parámetros espermáticos en oligospermia, astenospermia y teratospermia con deficiencia de protamina en varones infértiles. MATERIAL Y MÉTODO: En este estudio de casos y controles, hubo 3 grupos experimentales que incluían oligospermia (n=100), astenospermia (n=100) y teratospermia (n=100), así como normospermia (n=100) como controles. Los análisis de esperma se realizaron de acuerdo con las recomendaciones de la Organización Mundial de la Salud (OMS, 2010), y se evaluó la calidad de la cromatina de los espermatozoides utilizando la tinción con Chromomycin A3 (CMA3) para cada muestra. RESULTADOS: La comparación de los datos entre los grupos indicó que el porcentaje de espermatozoides con deficiencia de protamina fue considerablemente diferente en pacientes con oligospermia, astenospermia y teratospermia en comparación con la de los controles. Sin embargo, no hubo una correlación importante entre la deficiencia de protamina nuclear de esperma y sus parámetros de los varones con teratospermia cuando se utilizaba la prueba de CMA3. En cuanto a las muestras de semen de oligospermia y astenospermia, los hallazgos mostraron las correlaciones negativas entre la deficiencia de protamina nuclear de esperma y la movilidad progresiva, así como la inmovilidad (p < 0,001). CONCLUSIÓN: La mayor proporción de espermatozoides con un empaquetado de cromatina anómalo se observó en las muestras astenospérmicas que en las de otros grupos experimentales, así como en los controles. Parece que la morfología normal no puede tener un valor diagnóstico valioso de la buena calidad de la cromatina de los espermatozoides, tanto como las características normales de movilidad, ya que las muestras con altas tasas de movilidad a menudo tienen menores deficiencias de protamina. Los hallazgos pueden ofrecer un soporte que promueva la futura aplicación clínica más amplia de las pruebas de integridad de la cromatina/ADN junto con el análisis del semen en la infertilidad masculina

Sperm chromatin condensation and single- and double-stranded DNA damage as important parameters to define male factor related recurrent miscarriage.

The aim of the present work is to characterize the relationship between sperm protamine deficiency and single- and double-stranded DNA damage and to assess the diagnostic potential of chromomycin A3 (CMA3). For that purpose, semen samples from 90 human males with different clinical features were included (fertile donors, patients with recurrent pregnancy loss [RPL], and infertile patients). DNA condensation was analyzed by CMA3 and different types of DNA fragmentation were analyzed through the comet assay. A positive correlation between DNA condensation and single-stranded DNA fragmentation was found (Rs = .456; p = .05). CMA3 presented differences between fertile donors and all other groups (p < .001). Interestingly, patients with RPL, who were able to achieve a pregnancy, and infertile patients showed similar values of CMA3 (p > .05). Receiver operating characteristic curves and the profiles obtained by the combination of Comet assays and CMA3 indicate that the CMA3 test may be an interesting approach to distinguish those subjects with higher pregnancy loss risk from fertile donors (CMA3 area under the curve 0.928, with a confidence interval of 0.849-1.000). The present work shows that DNA condensation is related to oxidative damage, which affects mainly protamine-rich regions. The profiles observed in different clinical groups showed that CMA3 might be useful for the diagnosis of RPL risk when combined with Comet assays.

Correlation Between Protamine-2 and miRNA-122 in Sperm from Heroin-addicted Men: A Case-Control Study.

PURPOSE: Recreational use of illicit drugs is one of the main factors affecting male fertility. However, the mechanisms of heroin smoke-associated damage to mature spermatozoa are still completely unknown. The aim of this study was to concomitantly examine the levels of protamine-2 gene and protein concentrations, the amount of miRNA-122 in seminal plasma and semen analysis findings in heroin-addicted men. MATERIALS AND METHODS: In a case control study, twenty-four fertile men that lacked any recreational drug abuse were considered as the healthy group, and 24 addicted men who used only heroin for at least four months were selected as the addicted group. Semen samples were gathered by masturbation after 2 - 5 days of sexual abstinence. Following the preparation of a semen analysis by computer-assisted sperm analysis according to WHO (2010), the level of protamine-2 gene expression in sperm and miRNA-122 in seminal plasma was measured using real-time sqPCR. Also, protamine-2 protein concentrations were quantified by nuclear protein extraction, SDS-Page and western blotting. RESULTS: Among the studied variables, body mass index (27.75±0.88 vs. 22.30±0.36, p=0.001), seminal pH (7.79±0.06 vs. 7.58±0.06, p=0.003), white blood cell count in semen (1.69±0.41 vs. 8.61±1.73, p=0.001), motility (65.51±2.57 vs. 41.96±3.58, p=0.001) and survival rate (87.41±1.00 vs. 71.50±4.59, p=0.002) of sperm cells was significantly different between the healthy and addicted groups. In addition, the levels of protamine-2 gene and protein expression in the addicted group (0.05±0.02 and 0.10±0.02, respectively) were significantly lower than the healthy group (3.59±0.94 and 0.27±0.06, respectively) (p=0.002 and p=0.017, respectively). Seminal miRNA-122 levels in addicted men (3.51±0.73) were statistically higher than in healthy men (1.52±0.54) (p=0.034). However, there were some significant relationship between the studied parameters and addiction (p<0.05). CONCLUSION: This is one study on human infertility that evaluates the effects of heroin on protamine deficiency and seminal small RNAs expression levels. Heroin abuse may lead to male infertility by causing leukocytospermia, asthenozoospermia, protamine deficiency, and seminal plasma miRNA profile alteration.

The study investigating the determination of protamine in seminal plasma from azoospermic donors: Suggestion of new methods to diagnose obstructive azoospermia, and to capture childbearing sperm for testicular sperm extraction (TESE) and insemination sperm injection (ICSI).

We analyzed seminal plasma of 88 normozoospermic, 40 oligozoospermic and 32 azoospermic donors. During this study, we focus to record the protamine concentration in the seminal plasma of azoospermic donors. The seminal protamine concentrations were found to be 19.6-62.8 IU/ml in normozoospermic donors; 25.4-100.8 IU/ml in oligozoospermic donors; and, most notably, 23.7-219.4 IU/ml in azoospermic donors. These results indicate that, based on seminal plasma protamine concentrations, even azoospermic donors were able to produce as much sperm as normo- and/or oligozoospermic donors. Using statistical analyses, significant differences were found between azoospermic and normozoospermic donors (p = 0.0018). Protamine content was found to be a direct marker for the presence of sperm. The data from this study provided evidence for a new therapeutic approach for testicular varicose veins, which are found in obstructive or non-obstructive azoospermia. High seminal protamine concentrations indicated the future possibility of acquiring childbearing sperm for insemination sperm injection (ICSI) and testicular sperm extraction (TESE), even with azoospermic donors. Given these results, we also suggest a new cut-off value for acquisition of childbearing sperm in selection for ICSI.

Relationship between sperm telomere length and sperm quality in infertile men.

Telomeres, noncoding and repetitive DNA sequences play a significant function in chromatin integrity. Telomere length is age-dependent in somatic cells, while it increases in sperm cell with age. Therefore, we aimed to assess sperm chromatin, leucocyte and sperm telomere length (LTL, STL) in spermatozoon of 38 infertile and 19 fertile men aged between 20 and 50 years. Protamine deficiency (chromomycin A3 test), DNA fragmentation (TUNEL assay), lipid peroxidation (Bodipy probe) and telomere length (quantitative real-time PCR) were assessed. A significant decrease in mean of sperm concentration and motility and a significant increase in means of sperm abnormal morphology, DNA fragmentation, lipid peroxidation and protamine deficiency were observed in infertile compared with fertile men. In addition, the mean of LTL and STL were significantly shorter in infertile men compared with fertile individuals. We observed significant associations between telomere length with sperm concentration, DNA fragmentation and lipid peroxidation. We hypothesised that increased oxidative stress in spermatozoa of infertile men can result in abnormal packaging of chromatin, damage of DNA and shorter sperm telomere length. Together, these anomalies may account for fertility failure in these individuals.

A heparin-modified palladium nanozyme for photometric determination of protamine.

Heparin was employed as the stabilizing agent in the synthesis of peroxidase-mimicking Pd nanoparticles. The heparin-capped Pd nanozyme can act as both the signal amplifier and the selective binder of protamine. The most efficient nanozyme with the mean size of 3.5 nm consists of 70.8% metallic Pd0 and 29.2% Pd2+ species. Enzyme kinetic studies show that the Km values are 0.036 mM for 3,3',5,5'-tetramethylbenzidine and 78 mM for H2O2. Protamine shows strong affinity to the heparin-capped Pd nanozyme, and induces an apparent aggregation of the nanoparticles. This results in a significant inhibition of the peroxidase-mimicking activities. Hence, the oxidation of TMB by H2O2 to a blue product with a maximum absorption at 652 nm is suppressed. Based on this finding, a photometric assay is developed for the determination of protamine. The linear response is in the concentration range 0.02 ~ 0.8 µg mL-1, and the limit of detection is 0.014 µg mL-1. This assay presents high selectivity toward other biological substances. Graphical abstract Highly active and selective Pd nanozyme was synthesized through adopting heparin as the capping agent for quantitative determination of protamine.

Polymorphisms of sperm protamine genes and CMA3 staining in infertile men with varicocele.

OBJECTIVES: The aim of this study was to evaluate polymorphisms of sperm protamine genes and their effects on the result of CMA3 staining in varicocele men. MATERIAL AND METHODS: In a case control study, 128 patients with male infertility due to varicocele and 128 controls were recruited. Polymorphisms of PRM1 and PRM2 genes in extracted DNA samples were assessed by PCR-SSCP and sequencing. Protamine deficiency was also indirectly estimated by CMA3 staining. RESULT: Nine different variants including six variants in PRM1 gene and three variants in PRM2 gene were found among varicocele patients. The results showed that sperm count, motility and morphology were significantly different between control group without gene variations and varicocele group who had several variations in their protamine genes (P<0.05). CONCLUSION: Therefore, PRM1 and PRM2 variations in varicocele patients are associated with the production of spermatozoa with more protamine deficiency and this is one of the possible causes of infertility due to varicocele.

Characterization of Human Sperm Protamine Proteoforms through a Combination of Top-Down and Bottom-Up Mass Spectrometry Approaches.

Protamine 1 (P1) and protamine 2 (P2) family are extremely basic, sperm-specific proteins, packing 85-95% of the paternal DNA. P1 is synthesized as a mature form, whereas P2 components (HP2, HP3, and HP4) arise from the proteolysis of the precursor (pre-P2). Due to the particular protamine physical-chemical properties, their identification by standardized bottom-up mass spectrometry (MS) strategies is not straightforward. Therefore, the aim of this study was to identify the sperm protamine proteoforms profile, including their post-translational modifications, in normozoospermic individuals using two complementary strategies, a top-down MS approach and a proteinase-K-digestion-based bottom-up MS approach. By top-down MS, described and novel truncated P1 and pre-P2 proteoforms were identified. Intact P1, pre-P2, and P2 mature proteoforms and their phosphorylation pattern were also detected. Additionally, a +61 Da modification in different proteoforms was observed. By the bottom-up MS approach, phosphorylated residues for pre-P2, as well as the new P2 isoform 2, which is not annotated in the UniProtKB database, were revealed. Implementing these strategies in comparative studies of different infertile phenotypes, together with the evaluation of P1/P2 and pre-P2/P2 MS-derived ratios, would permit determining specific alterations in the protamine proteoforms and elucidate the role of phosphorylation/dephosphorylation dynamics in male fertility.

An additional marker for sperm DNA quality evaluation in spermatozoa of male partners of couples undergoing assisted reproduction technique (IVF/ICSI): Protamine ratio.

The aim of this study was to evaluate the relationship between the protamine ratio (P1/P2), DNA fragmentation of spermatozoa and protamine deficiency. Patients were grouped into fertile (G1; n = 151) and sub-fertile (G2; n = 121). DNA fragmentation in spermatozoa was analysed by a TUNEL assay (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling), and the protamination was determined by CMA3 staining, while Western blot was used to measure protamine P1 and P2. While sperm DNA fragmentation (SDF) and protamine ratio were significantly elevated in G2 compared with G1 (12.31 ± 7.01% vs. 17.5 ± 9.5%; p = .001) and (0.91 ± 0.43 vs. 0.75 ± 0.42; p = .003); respectively, the CMA3 positive showed no difference at all between G1 and G2. In G1, the CMA3 positive correlated negatively with the P1/P2 ratio and SDF (r = -.586, r = -.297; p = .001 respectively). In contrast, the protamine ratio correlated positively with SDF (r = .356; p = .001). In G2, no correlation was observed between CMA3 positive, SDF and the P1/P2 ratio but the P1/P2 ratio showed a positive correlation with SDF (r = .479; p = .001). In conclusion, the spermatozoa DNA deterioration was closely associated with abnormal protamination but showed an association with the protamine ratio, more than with CMA3 positive. Therefore, for the evaluation of DNA damage in spermatozoa, the P1/P2 ratio might act as an additional biomarker.

Rapid Equilibrated Colorimetric Detection of Protamine and Heparin: Recognition at the Nanoscale Liquid-Liquid Interface.

Demand for rapid quantitation of polyions such as heparin and protamine are ever growing. Previous paper-based and polymeric optical and electrochemical sensing devices required more than several hours for signal stabilization. Therefore, signals were acquired with fixed sample exposure time modes, which was time-consuming and technically demanding. We present here for the first time the optical detection of protamine and heparin in equilibrium mode with emulsified nanospheres. The method significantly shortens the response time from hours to typically less than 10 s and offers tunable, sensitive, and colorimetric detection within the clinically relevant range (10 to 100 mg/L) for heparin. The improved characteristics are attributable to the small size of the nanospheres (ca. 50 nm in diameter) as well as the reversible recognition at the nanoscale liquid-liquid interface. Detection of the anticoagulant heparin was also successfully demonstrated in human blood serum background.

Electrostatically controlled fluorometric assay for differently charged biotargets based on the use of silver/copper bimetallic nanoclusters modified with polyethyleneimine and graphene oxide.

An electrostatically controlled fluorometric assay is described that is based on the use of silver/copper bimetallic nanoclusters. The nanoclusters were coated with polyethyleneimine (PEI-Ag/CuNCs). At pH 7.4, these particles are positively charged. Their blue fluorescence (with excitation/emission peaks at 341/464 nm) depends on local pH values and temperature. If graphene oxide (which is negatively charged at pH 7.4) is introduced, the fluorescence of the PEI-Ag/CuNCs is quenched. Based on various electrostatic interactions, three kinds of biomacromolecules were detected by fluorometry. These include (negatively charged) heparin, (positively charged) protamine, and (virtually uncharged) trypsin. Heparin is detected by using GO/PEI-Ag/CuNCs, protamine by using GO/heparin/PEI-Ag/CuNCs, and trypsin by using GO/protamine/heparin/PEI-Ag/CuNC. The detection limits and linear ranges are 4.8 nM and 10-450 nM for heparin, 0.09 µg·mL-1 and 0.25-5 µg·mL-1 for protamine, and 0.03 µg·mL-1 and 0.05-1 µg·mL-1 for trypsin. Zeta potentials of the various substances in the system were determined to elucidate the detection mechanism. Comceivably, the method provides a widely applicable approach for electrostatically controlled biomolecular assays. Graphical abstract Schematic presentation of electrostatically controlled fluorometric assay for the detection of heparin, protamine, and trypsin based on the silver/copper bimetallic nanoclusters modified with polyethyleneimine and graphene oxide.

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

Protamine and heparin are the most important polyionic drugs used during surgeries and extracorporeal therapies. In this article, a selective and sensitive fluorescence method for the detection of both protamine and heparin was developed by using bovine serum albumin stabilised copper nanoclusters. Blue emitting fluorescent copper nanoclusters were synthesized in aqueous solution using bovine serum albumin as a capping agent and a reducing agent. A one pot microwave assisted method was adopted to synthesize fluorescent copper nanoclusters showing emission at 410 nm upon excitation at 330 nm. The fluorescence of copper nanoclusters was found to be enhanced after the addition of protamine and the limit of detection obtained is 0.12 ng mL-1. The significant enhancement in fluorescence can be attributed to the electrostatic interactions between the copper nanocluster and protamine. In contrast, the enhanced fluorescence intensity of the copper nanocluster with protamine added was decreased after the addition of heparin, and the copper nanocluster regained its original fluorescence intensity. This can be attributed to the strong interaction of protamine with heparin and the limit of detection was calculated as 0.0406 ng mL-1. The selectivity and sensitivity of the sensor for both protamine and heparin were also determined in the presence of potentially co-existing biomolecules, cations, and anions and satisfactory results were obtained. Additionally the validity of the proposed protamine and heparin sensor was attested in real sample matrices such as human urine samples and human blood serum samples. The results exhibited that the recovery percentage of protamine and heparin reached 98-99% and 92-99% in urine samples and 97-99% in serum samples.