Biological Media Research Articles

Modeling of the high-resolution optical-coherence diagnostics of bi-refringent biological tissues

We present a computer model of the polarization-sensitive interference diagnostics of the bi-refringent biological media, with a particular example of the lamella of eye cornea. The diagnostic procedure employs the modified Mach–Zehnder interferometer with controllable phase retardation of the reference wave, separate observation of the orthogonal linearly-polarized interference signals, and evaluation of the phases and amplitudes of their variable (AC) components. The data obtained permit to determine the mean refractive index as well as the difference between the extraordinary and ordinary refractive indices, which, in turn, indicates the optical axis and the collagen fibers’ orientation in the lamella. The modelled procedure enables the sample structure diagnostics with the longitudinal and lateral resolution ∼100 nm and ∼1.8 μm, correspondingly. In particular, it permits a reliable detection and quantitative characterization of a thin (<100 nm) near-surface layer where the mean refractive index differs by less than 1% from that in the main volume (due to the different orientation of the collagen fibers). The diagnostic approach, developed in the paper, can be useful in various problems of structure characterization of optically-anisotropic biological tissues.

A BODIPY‐Based Molecular Rotor in Giant Unilamellar Vesicles: A Case Study by Polarization‐Resolved Time‐Resolved Emission and Transient Absorption Spectroscopy

AbstractBODIPY and BODIPY‐derived systems are widely applied as fluorophores and as probes for viscosity detection in solvents and biological media. Their orientational and rotational dynamics in biological media are thus of vital mechanistic importance and extensively investigated. In this contribution, polarization‐resolved confocal microscopy is used to determine the orientation of an amphiphilic BODIPY‐cholesterol derivative in homogeneous giant unilamellar vesicles (GUV) made from 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC). The BODIPY‐moiety of the molecule is placed near the polar headgroups, and the cholesterol moiety is embedded in the membrane along the acyl chain of the lipids. The rotational relaxation of fluorophore is conventionally investigated by time‐resolved emission anisotropy (TEA); and this method is also used here. However, TEA depends on the emission of the fluorophore and may not be useful to probe rotational dynamics of the non‐emissive triplet states. Thus, we employ femtosecond transient absorption anisotropy (TAA), that relies on the absorption of the molecule to complement the studies of the amphiphilic BODIPY in DCM and GUV. The photoinduced anisotropy of the BODIPY molecule in DCM decays tri‐exponentially, the decay components (sub‐5 ps, 43 ps and 440 ps) of anisotropy are associated with the non‐spherical shape of the BODIPY molecule. However, the anisotropy decay in homogenous GUVs follows a biexponential decay; which arises from the wobbling‐in‐a‐cone motion of the non‐spherical molecule in the high viscous lipid bilayer media. The observations for the BODIPY‐chol molecule in the GUV environment by TAA will extend to the investigation of non‐emissive molecules in cellular environment since GUV structure and size resembles the membrane of a biological cell.

The Eligibility of the Encyclopedia of Circulatory System Diseases and Disorders Based on Traditional Medicinal Plants for Hypertension as Learning Media

Learning media is an essential element to support the success of learning activities. It is used stimulate the thoughts, feelings, attention, and interest of students to learn. Learning media can be developed by adding concepts and photos from the results of a research. The purpose of this study was to determine the feasibility of the encyclopedia of circulatory system diseases and disorders as a learning media. The content of encyclopedia contains the result from the inventory of medicinal plants for hypertension at Babane Village, Bengkayang, Indonesia. This study applied a research and development method. This development procedure refers to the Sugiyono development model, which consists of five stages namely potential and problems, data collection, product design, design validation, and design revision. The validity of the encyclopedia was obtained through content validation executed by five experts in the field of both biology and learning media. Encyclopedia validation is reviewed from four aspects: content, presentation, language, and graphics. Validation analysis applied the Lawshe's content validity ratio (CVR) and content validity index (CVI) approach. The results showed that the average of CVR was 1.00 which result in the CVI value of 1.00 in the "valid" category. Based on the result, can be concluded that the encyclopedia was feasible as a learning media

Fractal relaxation model with a nonlinear diffusion coefficient for fitting anomalous diffusion data in magnetic resonance imaging

In this paper a relaxation model of signal attenuation in diffusion-weighted magnetic resonance imaging (dMRI) with varying diffusion coefficient in terms of fractal derivative is proposed, in which the diffusion coefficient is a power law of the effective diffusion time. The relaxation model provides measures of diffusion constant, fractal dimension of diffusive trajectory of water molecule and the time power-law behavior of the diffusion coefficient. The proposed model was used to describe the magnetic resonance attenuation signal of the bullfrog sciatic nerve, and the corresponding spectral entropy was calculated to detect the environmental complexity in bullfrog sciatic nerve for water molecular diffusion. The results showed that the fractal derivative relaxation model (the VDC model) can accurately depict the diffusion pattern of water molecules in complex heterogeneous biological media at large b values. The VDC model provides an alternative theoretical reference for biological tissue detection based on time-dependent diffusion of water molecules.

012 facets modulated LDH composite for neurotoxicity risk assessment through direct electrochemical profiling of dopamine

Rising concerns of pesticide-induced neurotoxicity and neurodegenerative diseases like Parkinson's, Alzheimer's, and Multiple Sclerosis, are exacerbated by overexposure to contaminated waterbodies. Therefore, evaluating the risk accurately requires reliable monitoring of related biomarkers like dopamine (DA) through electrochemical detection. Layered double hydroxides (LDHs) have shown great potential in sensors. However, to meet the challenges of rapid detection of large patient cohorts in real-time biological media, they should be further tailored to display superior analytical readouts. Herein, a ternary LDH (Ni2CoMn0.5) was integrated with the sheets of thermally reduced graphene oxide (trGO), to expose more highly active edge planes of the LDH, as opposed to its generally observed inert basal planes. The improvement in detection performance through such a modulated structure-property is a prospect that hasn't been previously explored for any other LDH-based materials employed in sensing applications. The 2 folds superior electrochemical activity exhibited by the face-on oriented LDH with trGO as compared to the pristine LDH material was further employed for direct detection of DA in real blood plasma samples. Moreover, the designed sensor exhibited exceptional selectivity towards the detection of DA with a limit of detection of 34.6 nM for a wide dynamic range of 0.001–5 mM with exceptional stability retaining 88.56% of the initial current even after storage in ambient conditions for 30 days.

Green synthesis of silver nanoparticles using Mentha crispa L. leaf extract for treatment of dye wastewater

Mentha crispa L. is one of Vietnam’s most precious folk medicines and is also a spice used in many delicious dishes in Vietnam and around the world. The use of Mentha crispa L. leaf extract as a reducing agent for Ag+ ions to synthesize silver nanoparticles is discussed in this paper. Single silver nanospheres were dispersed in biological media and their sizes were controlled in the range of 20-80 nm. Factors affecting particle size and shape such as extract concentration, AgNO3 concentration, reaction time, and temperature were investigated to determine the optimal parameters for particle synthesis. The optical properties, dispersion, crystal structure, morphology, and sizes of silver nanoparticles were investigated through UV-Vis absorption spectroscopy, dynamic light scattering (DLS) measurements, X-ray diffraction, and transmission electron microscopy (TEM). The functional groups on the L.AgNPs were determined by Fourier-transform infrared (FTIR) transmittance spectra. The synthesised silver nanoparticles were used to treat methylene blue (MB) dye, the main component of dye wastewater, based on their photocatalytic properties. The results show that in the presence of L.AgNPs, the photodegradation efficiency of NaBH4 or H2O2 reducing agents is much higher, up to 95% of illumination.

Multifunctional ferromagnetic nanodiamond for dual-mode fluorescence imaging and magnetic drug targeting

The use of nanoparticles as drug delivery vehicles has been receiving much attention in recent years, especially for cancer treatment, with high hope to develop nanocarriers that can deliver therapeutic compounds to the target sites more efficiently. Magnetic drug targeting can be an effective way to deliver drugs to specific areas controlled by magnetic fields at the tumor area; possible to guide and transport anticancer drugs bound to magnetic materials to the tumor site. In this study, magnetic nanodiamond (MND) particles are used as an efficient drug delivery vehicle which can be targeted and imaged simultaneously. A protein Human serum albumin (HSA) is conjugated to MND to improve dispersion in biological medium and to facilitate controlled release of the drug. The particle loaded with clinical drug doxorubicin (DOX) and the effectiveness of the therapy against the cancer cells in-vitro was studied. The DOX-loaded MNDa-HSA remained stable for a prolonged period, rendering its ability to penetrate and release its drug into cells. When nanodiamond-DOX complexes are exposed to magnetic field (MF), their IC50 values are reduced significantly lower than those of free DOX and MNDa-HSA-DOX (without MF). The results indicate that MNDa-HSA could be a potential carrier for vectoring drugs using an external magnetic field, also enabling to be used as a biolabeling agent which can be tracked using fluorescence imaging.

Circumventing Physicochemical Barriers of Cyclometalated Gold(III) Dithiocarbamate Complexes with Protein-Based Nanoparticle Delivery to Enhance Anticancer Activity.

Optimizing the bioavailability of drug candidates is crucial to successful drug development campaigns, especially for metal-derived chemotherapeutic agents. Nanoparticle delivery strategies can be deployed to overcome physicochemical limitations associated with drugs to improve bioavailability, pharmacokinetics, efficacy, and minimize toxicity. Biodegradable albumin nanoconstructs offer pragmatic solutions for drug delivery of metallodrugs with translational benefits in the clinic. In this work, we explored a logical approach to investigate and resolve the physicochemical drawbacks of gold(III) complexes with albumin nanoparticle delivery to improve solubility, enhance intracellular accumulation, circumvent premature deactivation, and enhance anticancer activity. We synthesized and characterized stable gold(III) dithiocarbamate complexes with a variable degree of cyclometalation such as phenylpyridine (C^N) or biphenyl (C^C) Au(III) framework and different alkyl chain lengths. We noted that extended alkyl chain lengths impaired the solubility of these complexes in biological media, thus adversely impacting potency. Encapsulation of these complexes in bovine serum albumin (BSA) reversed solubility limitations and improved cancer cytotoxicity by ∼25-fold. Further speciation and mechanism of action studies demonstrate the stability of the compounds and alteration of mitochondria bioenergetics, respectively. We postulate that this nanodelivery strategy is a relevant approach for translational small-molecule gold drug delivery.

Rapid SERS Detection of Botulinum Neurotoxin Type A.

Surface-enhanced Raman scattering (SERS) is a powerful technique for decoding of 2-5-component mixes of analytes. Low concentrations of analytes and complex biological media are usually non-decodable with SERS. Recognition molecules, such as antibodies and aptamers, provide an opportunity for a specific binding of ultra-low contents of analyte dissolved in complex biological media. Different approaches have been proposed to provide changes in SERS intensity of an external label upon binding of ultra-low contents of the analytes. In this paper, we propose a SERS-based sensor for the rapid and sensitive detection of botulinum toxin type A. The silver nanoisland SERS substrate was functionalized using an aptamer conjugated with a Raman label. The binding of the target affects the orientation of the label, providing changes in an analytical signal. This trick allowed detecting botulinum toxin type A in a one-stage manner without additional staining with a monotonous dose dependence and a limit of detection of 2.4 ng/mL. The proposed sensor architecture is consistent with the multiarray detection systems for multiplex analyses.

Numerical study of a D-shaped optical fiber SPR biosensor for monitoring refractive index variations in biological tissue via a thin layer of gold coated with titanium dioxide

This study aims to explore the numerical analysis of the impact of integrating titanium oxide (TiO2) into a D-shaped optical fiber biosensor based on surface plasmon resonance (SPR). A thin layer of gold (Au) is applied to the flat section of the fiber, which is also coated with a thin layer of titanium dioxide (TiO2). The behavior and performance of the proposed biosensor for use in biological environments are evaluated using the finite element method (FEM). The optical response of SPR-based biosensors is highly dependent on the analyzed medium, enabling the detection of pathogenic cells and abnormalities in biological tissues. This provides high sensitivity and selectivity, as well as real-time detection accuracy and speed. In this study, the biosensor is incorporated into a biological medium with a refractive index that varies with wavelength. A series of simulations have been conducted to plot the spectra of transmissions, absorptions, and dielectric losses obtained in the output of the sensor instrument. From these spectra, the corresponding surface plasmon resonance (SPR) wavelength (λSPR) within the visible-near-infrared band can be determined. Taking into account the various parameters that influence plasmonic interactions, the biosensor's performance parameters, in particular sensitivity and refractive index resolution have been optimized. Our results show that the presence of the TiO2 layer improves the performance of the proposed sensor and offers the possibility of adjusting the resonance wavelength (λSPR). In addition, our proposed sensor can achieve a better resolution of 7.50×10-6[RIU] in 1.34-143 range of analyte refractive index, which notably exceeds that of current technologies. This opens up new prospects in the field of chemical and biological detection.

Molecular Mechanism of Toxic Effects of Tritium Water in Different Biological Media

Molecular Mechanism of Toxic Effects of Tritium Water in Different Biological Media

Fouling-resistant electrode for electrochemical sensing based on covalent-organic frameworks TpPA-1 dispersed cabon nanotubes

The key problem that limits the practical applications of nonenzymatic electrochemical sensors in biological media, is the biofouling and chemical fouling of electrodes due to the adsorption of biological molecules and oxidation (reduction) products. Electrode fouling will cause low accuracy, poor stability, and low sensitivity. Here, a simple and efficient antifouling electrode was demonstrated for electrochemical sensing based on covalent-organic framework (COF) TpPA-1 and carboxylic multi-walled carbon nanotubes (CNT) composites. COF TpPA-1 possesses abundant hydrophilic groups, which assisted the dispersion of CNT in water and formed uniform composites by π-π interaction. In addition, the introduction of CNT into the composites improved the electron transfer rate of COF TpPA-1. The antifouling interface was characterized by electrochemistry, contact angle measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrode showed good chemical and bio-fouling resistant performance for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH) and uric acid (UA) in real serum samples.

A single n-type semiconducting polymer-based photo-electrochemical transistor

Conjugated polymer films, which can conduct both ionic and electronic charges, are central to building soft electronic sensors and actuators. Despite the possible interplay between light absorption and the mixed conductivity of these materials in aqueous biological media, no single polymer film has been utilized to create a solar-switchable organic bioelectronic circuit that relies on a fully reversible and redox reaction-free potentiometric photodetection and current modulation. Here we demonstrate that the absorption of light by an electron and cation-transporting polymer film reversibly modulates its electrochemical potential and conductivity in an aqueous electrolyte, which is harnessed to design an n-type photo-electrochemical transistor (n-OPECT). By controlling the intensity of light incident on the n-type polymeric gate electrode, we generate transistor output characteristics that mimic the modulation of the polymeric channel current achieved through gate voltage control. The micron-scale n-OPECT exhibits a high signal-to-noise ratio and an excellent sensitivity to low light intensities. We demonstrate three direct applications of the n-OPECT, i.e., a photoplethysmogram recorder, a light-controlled inverter circuit, and a light-gated artificial synapse, underscoring the suitability of this platform for a myriad of biomedical applications that involve light intensity changes.

Comparative Studies of Different Preservation Methods and Relative Freeze-Drying Formulations for Extracellular Vesicle Pharmaceutical Applications.

Extracellular vesicles (EVs) have been studied for years for their role as effectors and mediators of cell-to-cell communication and their potential application to develop new and increasingly performing nanotechnological systems for the diagnosis and/or treatment of many diseases. Given all the EVs applications as just isolated, functionalized, or even engineered cellular-derived pharmaceuticals, the standardization of reliable and reproducible methods for their preservation is urgently needed. In this study, we isolated EVs from a healthy blood cell line, B lymphocytes, and compared the effectiveness of different storage methods and relative freeze-drying formulations to preserve some of the most important EVs' key features, i.e., concentration, mean size, protein content, and surface antigen's expression. To develop a preservation method that minimally affects the EVs' integrity and functionality, we applied the freeze-drying process in combination with different excipients. Since EVs are isolated not only from body fluids but also from culture media conditioned by the cells growing there, we decided to test both the effects of the traditional pharmaceutical excipient and of biological media to develop EVs solidified products with desirable appearance and performance properties. Results showed that some of the tested excipients, i.e., sugars in combination with dextran and glycine, successfully maintained the stability and integrity of EVs upon lyophilization. In addition, to evaluate the preservation of the EVs' biological activity, we assessed the cytotoxicity and internalization ability of the reconstituted EVs in healthy (B lymphocytes) and tumoral (Burkitt's lymphoma) cells. Reconstituted EVs demonstrated toxicity only toward the cancerous cells, opening new therapeutic opportunities for the oncological field. Furthermore, our study showed how some biological or cellular-conditioned fluids, commonly used in the field of cell cultures, can act not only as cryoprotectants but also as active pharmaceutical ingredients, significantly tuning the therapeutic effect of EVs, even increasing their cellular internalization.

Carfilzomib-Loaded Ternary Polypeptide Nanoparticles Stabilized by Polycationic Complexation

Carfilzomib (CFZ) is a second-generation proteasome inhibitor showing great efficacy in multiple myeloma treatment, yet its clinical applications for other diseases such as solid cancers are limited due to low aqueous solubility and poor biostability. Ternary polypeptide nanoparticles (tPNPs) are drug carriers that we previously reported to overcome these pharmaceutical limitations by entrapping CFZ in the core of the nanoparticles and protecting the drugs from degradation in biological media. However, preclinical studies revealed that tPNPs would require further improvement in particle stability to suppress initial burst drug release and thus achieve prolonged inhibition of proteasome activity with CFZ against tumor cells in vivo. In this study, CFZ-loaded tPNPs are stabilized by polycations which have varying pKa values and thus differently modulate nanoparticle stability in response to solution pH. Through polyion complexation, the polycations appeared to stabilize the core of tPNPs entrapping CFZ-cyclodextrin inclusion complexes while allowing for uniform particle size before and after freeze drying. Interestingly, CFZ-loaded tPNPs (CFZ/tPNPs) showed pH-dependent drug release kinetics, which accelerated CFZ release as solution acidity increased (pH < 6) without compromising particle stability at the physiological condition (pH 7.4). In vitro cytotoxicity and proteasome activity assays confirmed that tPNPs stabilized with cationic polymers improved bioactivity of CFZ against CFZ-resistant cancer cells, which would be greatly beneficial in combination with pH-dependent drug release for treatment of solid cancers with drug resistance and tumor microenvironment acidosis by using CFZ and other proteasome inhibitors.

Technology of experiments on non-thermal effects of powerful lectromagnetic pulses on natural and artificial environments

The features of the technology of experiments on the non-thermal effects of high-power nanosecond pulses are considered using the example of a setup used to modify biological media and other objects with heterogeneous electrophysical characteristics. An experimental setup has been created to study the non-thermal effects of high-power pulses on samples of various materials, which generates pulses with a repetition frequency of up to 500 Hz, amplitude up to 60 kV and duration 5 ns. Simulation of transient processes in the equivalent electrical circuit of the load was carried out, and a biological one was used as a load material placed in a microplate.

Correspondence of mean apparent propagator MRI metrics with phosphorylated tau and astrogliosis in chronic traumatic encephalopathy.

Chronic traumatic encephalopathy is a neurodegenerative disease that is diagnosed and staged based on the localization and extent of phosphorylated tau pathology. Although its identification remains the primary diagnostic criteria to distinguish chronic traumatic encephalopathy from other tauopathies, the hyperphosphorylated tau that accumulates in neurofibrillary tangles in cortical grey matter and perivascular regions is often accompanied by concomitant pathology such as astrogliosis. Mean apparent propagator MRI is a clinically feasible diffusion MRI method that is suitable to characterize microstructure of complex biological media efficiently and comprehensively. We performed quantitative correlations between propagator metrics and underlying phosphorylated tau and astroglial pathology in a cross-sectional study of 10 ex vivo human tissue specimens with 'high chronic traumatic encephalopathy' at 0.25 mm isotropic voxels. Linear mixed effects analysis of regions of interest showed significant relationships of phosphorylated tau with propagator-estimated non-Gaussianity in cortical grey matter (P = 0.002) and of astrogliosis with propagator anisotropy in superficial cortical white matter (P = 0.0009). The positive correlation between phosphorylated tau and non-Gaussianity was found to be modest but significant (R2 = 0.44, P = 6.0 × 10-5) using linear regression. We developed an unsupervised clustering algorithm with non-Gaussianity and propagator anisotropy as inputs, which was able to identify voxels in superficial cortical white matter that corresponded to astrocytes that were accumulated at the grey-white matter interface. Our results suggest that mean apparent propagator MRI at high spatial resolution provides a means to not only identify phosphorylated tau pathology but also detect regions with astrocytic pathology and may therefore prove diagnostically valuable in the evaluation of concomitant pathology in cortical tissue with complex microstructure.

In situ synthesis of gold nanoparticles on layered double hydroxide nanoparticles for multiplexing molecular imaging of single cells

Quasi-spherical gold nanoparticles (AuNPs) are the most widely used surface-enhanced Raman scattering (SERS) nanotags. However, their surface plasmon resonance properties are significantly restricted by their poor colloidal stability in biological media. Herein, we developed a new strategy for in situ synthesis of AuNPs on layered double hydroxide (LDH) nanoparticles to improve the colloidal stability of AuNPs for SERS imaging with multiplexing capability using single laser excitation. The hybridized LDH-AuNPs were constructed via in situ growth of AuNPs on lactic acid-LDH nanoparticles. The size of AuNPs was tuned by changing the concentration of LDH. The LDH-AuNPs were further functionalized with Raman reporter molecules (Ra) to obtain LDH-AuNPs-Ra as SERS nanotags, which were examined in terms of the colloidal stability and photostability in biological media as well as cellular uptake in J774A.1 macrophage cell culture by single cell mapping via confocal Raman microscopy. The cellular uptake of multiple LDH-AuNPs-Ra functionalized with different Raman reporter molecules were further investigated, where the multiplexing capability of SERS assay endows simultaneous detection of multiple LDH-AuNPs-Ra distribution after cellular uptake for cell imaging. In summary, the LDH-supported in situ synthesis of AuNPs have shown the merits of stabilizing AuNPs by using LDH for SERS imaging, as well as demonstrating the multiplexing molecular imaging of single cells. This work thus provides a promising strategy and a new bioimaging nanoplatform for various biomedical studies in the near future.

A Simple, Stable, and Highly Sensitive Spectrophotometric Method for the Determination of Arsenic(III) from Different Biological Media in the Presence of Nanosilica-Cysteine Composite

This paper describes a selective and fairly stable colorimetric approach to determine trace amounts of arsenic conjugated with nanosilica-cysteine composite in various aqueous and biological samples in milligram per liter (mg/L) using Leucocrystal Violet (LCV) as a chromogenic reagent. Attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy analysis was applied to characterize the composite. Novelty of this method is dealing with the presence of nanosilica which is reflected in the difficulty of obtaining a clear solution. The maximum absorbance is measured and Beer's law shows linearity over the concentration range of (0.75 to 5.00 mg/L) of As(III) at 590 nm. The molar absorptivity, Sandell’s sensitivity, and detection limit of the method were found to be 6.00 × 105 L/mol.cm, 8.55 × 10-2 μg/cm2, and 0.043 mg/L, respectively. The optimum reaction conditions and other analytical parameters were evaluated. Arsenic was successfully detected in a variety of aqueous and biological samples using the proposed method.

Prostate specific antigen quantification in human serum supported by the designed four-in-one octabranched peptides and AgNPs-based signal amplifier

BackgrounIt remains challenging for biosensors to directly detect clinical targets in complex biological media with high selectivity and low fouling. MethodsHerein, an antifouling and ultrasensitive biosensor supported by the designed four-in-one octabranched peptides and signaling amplification strategy of silver nanoparticles (AgNPs) was constructed for prostate specific antigen (PSA) quantification in human serum. Chondroitin sulfate functionalized polyaniline (PANI) nanowires and gold nanoparticles (AuNPs) were electrodeposited onto the electrode in sequence to promote electrons transport, and followed by the attachment of the designed octabranched peptides. Significant findingsThe peptides were specially designed to contain four structural domains, namely anchoring domain (CC), linking domain (PPPP), antifouling domain (EKEKEKE), and recognition domain (HSSKLQK). AgNPs loaded on graphene oxide were assembled onto peptides as a signal amplification strategy. The peptides were specifically sheared off by PSA, resulting in a significantly reduced electrochemical response that can be used to sensitively indicate PSA concentration. The antifouling biosensor exhibited a linear response range from 1 × 10−14 to 1 × 10−6 M, with a low detection limit of 1.33 × 10−15 M. Furthermore, the biosensor was employed to detect PSA in clinical samples based on the four-in-one octabranched peptides, indicating feasibility of the biosensor for early clinical diagnosis.