Enhanced biosensing of tumor necrosis factor-alpha based on aptamer-functionalized surface plasmon resonance substrate and Goos-Hänchen shift.

Tumor necrosis factor-alpha (TNF-α) serves as a crucial biomarker in various diseases, necessitating sensitive detection methodologies. This study introduces an innovative approach utilizing an aptamer-functionalized surface plasmon resonance (SPR) substrate together with an ultrasensitive measure, the Goos-Hänchen (GH) shift, to achieve sensitive detection of TNF-α. The developed GH-aptasensing platform has shown a commendable figure-of-merit of 1.5 × 104 µm per RIU, showcasing a maximum detectable lateral position shift of 184.7 ± 1.2 µm, as characterized by the glycerol measurement. Employing aptamers as the recognition unit, the system exhibits remarkable biomolecule detection capabilities, including the experimentally obtained detection limit of 1 aM for the model protein bovine serum albumin (BSA), spanning wide dynamic ranges. Furthermore, the system successfully detects TNF-α, a small cytokine, with an experimental detection limit of 1 fM, comparable to conventional SPR immunoassays. This achievement represents one of the lowest experimentally derived detection limits for cytokines in aptamer-based SPR sensing. Additionally, the application of the GH shift marks a ground breaking advancement in aptamer-based biosensing, holding significant promise for pushing detection limits further, especially for small cytokine targets.

Symmetrical anisotropy enables dynamic diffraction control in photonics.

Despite the steady advancements in nanofabrication made over the past decade that had prompted a plethora of intriguing applications across various fields, achieving compatibility between miniaturized photonic devices and electronic dimensions remains unachievable due to the inherent diffraction limit of photonic devices. Herein, we present an approach based on anisotropic scaling of the shapes of photonic crystals (PhCs) to overcome the diffraction limit and achieve controlled diffraction limit along the ΓX direction. Thus, we demonstrate that scaling the direction perpendicular to the wave's propagation (y-direction) by 1/2 and 1/4 significantly improves the diffraction limit by two and four orders of magnitude, respectively. This approach opens up possibilities for high-frequency wave guiding in a cermet configuration, which was previously unachievable. Furthermore, we illustrate the existence of a quasi-bound state in the continuum (QBICs) in asymmetric dimer network-type photonic crystals (PhCs).

A Composite-Type MEMS Pirani Gauge for Wide Range and High Accuracy.

To achieve a wide range and high accuracy detection of the vacuum level, for example, in an encapsulated vacuum microcavity, a composite-type MEMS Pirani gauge has been designed and fabricated. The Pirani gauge consists of two gauges of different sizes connected in series, with one gauge having a larger heat-sensitive area and a larger air gap for extending the lower measurable limit of pressure (i.e., the high vacuum end) and the other gauge having a smaller heat-sensitive area and a smaller air gap for extending the upper measurable limit. The high-resistivity titanium metal was chosen as the thermistor; SiNx was chosen as the dielectric layer, considering the factors relevant to simulation and manufacturing. By simulation using COMSOL Multiphysics and NI Multisim, a range of measurement of 2 × 10-2 to 2 × 105 Pa and a sensitivity of 52.4 mV/lgPa were obtained in an N2 environment. The performance of the fabricated Pirani gauge was evaluated by using an in-house made vacuum test system. In the test, the actual points of measurement range from 6.6 × 10-2 to 1.12 × 105 Pa, and the highest sensitivity is up to 457.6 mV/lgPa. The experimental results are better in the range of measurement, sensitivity, and accuracy than the simulation results. The Pirani gauge proposed in this study is simple in structure, easy to manufacture, and suitable for integration with other MEMS devices in a microcavity to monitor the vacuum level therein.

Nanocarbons for Biology and Medicine: Sensing, Imaging, and Drug Delivery.

Nanocarbons with different dimensions (e.g., 0D fullerenes and carbon nanodots, 1D carbon nanotubes and graphene nanoribbons, 2D graphene and graphene oxides, and 3D nanodiamonds) have attracted enormous interest for applications ranging from electronics, optoelectronics, and photovoltaics to sensing, bioimaging, and therapeutics due to their unique physical and chemical properties. Among them, nanocarbon-based theranostics (i.e., therapeutics and diagnostics) is one of the most intensively studied applications, as these nanocarbon materials serve as excellent biosensors, versatile drug/gene carriers for specific targeting in vivo, effective photothermal nanoagents for cancer therapy, and promising fluorescent nanolabels for cell and tissue imaging. This review provides a systematic overview of the latest theranostic applications of nanocarbon materials with a comprehensive comparison of the characteristics of different nanocarbon materials and their influences on theranostic applications. We first introduce the different carbon allotropes that can be used for theranostic applications with their respective preparation and surface functionalization approaches as well as their physical and chemical properties. Theranostic applications are described separately for both in vitro and in vivo systems by highlighting the protocols and the studied biosystems, followed by the toxicity and biodegradability implications. Finally, this review outlines the design considerations for nanocarbon materials as the key unifying themes that will serve as a foundational first principle for researchers to study, investigate, and generate effective, biocompatible, and nontoxic nanocarbon materials-based models for cancer theranostics applications. Finally, we summarize the review with an outlook on the challenges and novel theranostic protocols using nanocarbon materials for hard-to-treat cancers and other diseases. This review intends to present a comprehensive guideline for researchers in nanotechnology and biomedicine on the selection strategy of nanocarbon materials according to their specific requirements.

Planar nonlinear metasurface optics and their applications.

Metasurfaces are artificial two-dimensional (2D) planar surfaces that consist of subwavelength 'meta-atoms' (i.e. metallic or dielectric nanostructures). They are known for their capability to achieve better and more efficient light control in comparison to their traditional optical counterparts. Abrupt and sharp changes in the electromagnetic properties can be induced by the metasurfaces rather than the conventional gradual accumulation that requires greater propagation distances. Based on this feature, planar optical components like mirrors, lenses, waveplates, isolators and even holograms with ultrasmall thicknesses have been developed. Most of the current metasurface studies have focused on tailoring the linear optical effects for applications such as cloaking, lens imaging and 3D holography. Recently, the use of metasurfaces to enhance nonlinear optical effects has attracted significant attention from the research community. Benefiting from the resulting efficient nonlinear optical processes, the fabrication of integrated all-optical nano-devices with peculiar functionalities including broadband frequency conversions and ultrafast optical switching will become achievable. Plasmonic excitation is one of the most effective approaches to increase nonlinear optical responses due to its induced strong local electromagnetic field enhancement. For instance, continuous phase control on the effective nonlinear polarizability of plasmonic metasurfaces has been demonstrated through spin-rotation light coupling. The phase of the nonlinear polarization can be continuously tuned by spatially changing the meta-atoms' orientations during second and third harmonic generation processes, while the nonlinear metasurfaces also exhibit homogeneous linear properties. In addition, an ultrahigh second-order nonlinear susceptibility of up to 104 pm V-1 has recently been reported by coupling the plasmonic modes of patterned metallic arrays with intersubband transition of multi-quantum-well layered substrate. In order to develop ultra-planar nonlinear plasmonic metasurfaces, 2D materials such as graphene and transition metal dichalcogenides (TMDCs) have been extensively studied based on their unique nonlinear optical properties. The third-order nonlinear coefficient of graphene is five times that of gold substrate, while TMDC materials also exhibit a strong second-order magnetic susceptibility. In this review, we first focus on the main principles of planar nonlinear plasmonics based on metasurfaces and 2D nonlinear materials. The advantages and challenges of incorporating 2D nonlinear materials into metasurfaces are discussed, followed by their potential applications including orbital angular momentum manipulating and quantum optics.

Study on the dual-Fano resonance generation and its potential for self-calibrated sensing.

Sensors based on Fano resonance (FR) have become a promising platform for various biological and chemical applications. However, most investigations on FR are limited to the generation of individual resonance. In this paper, based on the coupling between surface plasmon polariton (SPP) and two photonic waveguide modes, a dual-FR system is designed and analyzed. To explain the coupling mechanism, an extended temporal coupled-mode model is established to provide the physical insight. The spectral response obtained from the model matches well with the numerical one. Due to the decoupled nature of the FRs, a self-calibrated or dual-parameter sensing scheme for refractive index and temperature is proposed. The refractive index sensitivity up to 765 nm/RIU and temperature sensitivity up to 0.087 nm/°C are obtained by wavelength interrogation with figure-of-merit (FOM) up to 33260.9 RIU-1 and 3.78 °C-1 respectively. The proposed sensor provides great potential in fields of the multi-parameter sensing.

Experimental and numerical investigation on hollow core photonic crystal fiber based bending sensor.

Recent progress in designing optimized microstructured optical fiber spreads an application scenario of optical fiber sensing. Here, we investigate the bending measurement based on a specially designed hollow core photonic crystal fiber (HC-PCF). Numerical simulation indicates that the bending sensitivity is mainly determined by the diameter of the hollow core and also depends on the coupled modes. Experimentally, a direction-independent bending sensor is fabricated by sandwiching a segment of specially designed HC-PCF into two segments of single mode fibers. The bending sensitivity of our device is improved 10 times by increasing the diameter of the hollow core. Bending measurement is validated at two orthogonal planes. The maximum sensitivity up to 2.8 nm/deg is obtained at 14° bending angle. Additionally, a low thermal sensitivity of 2.5 pm/°C is observed from 18°C to 1000°C. The sensor is robust, easy to fabricate and cost effective, which is promising in the field of small-angle bending measurement under a large temperature range.

Compact polarization beam splitter assisted by subwavelength grating in triple-waveguide directional coupler.

A polarization beam splitter (PBS) is one of the key components for manipulating different polarization states in the areas of optical interconnection and communication. In this paper, a PBS with two coupling regions using a subwavelength grating (SWG) waveguide as a bridge is proposed and investigated on a 340-nm silicon-on-insulator platform. The PBS is designed with a triple-waveguide directional coupler consisting of two identical silicon waveguides and an SWG waveguide sandwiched between them. The tailorable dispersion relation of the SWG waveguide offers a flexible design freedom. With the optimized grating period and duty ratio, the input TE mode will experience efficient coupling between the silicon waveguide and the SWG waveguide, while the TM mode can directly pass through without influence. The results show that with a device length of 6.5 µm, the extinction ratios and insertion losses of the two modes are higher than 27 dB and lower than 0.3 dB at a wavelength of 1550 nm, respectively.

New Generation Cadmium-Free Quantum Dots for Biophotonics and Nanomedicine.

This review summarizes recent progress in the design and applications of cadmium-free quantum dots (Cd-free QDs), with an emphasis on their role in biophotonics and nanomedicine. We first present the features of Cd-free QDs and describe the physics and emergent optical properties of various types of Cd-free QDs whose applications are discussed in subsequent sections. Selected specific QD systems are introduced, followed by the preparation of these Cd-free QDs in a form useful for biological applications, including recent advances in achieving high photoluminescence quantum yield (PL QY) and tunability of emission color. Next, we summarize biophotonic applications of Cd-free QDs in optical imaging, photoacoustic imaging, sensing, optical tracking, and photothermal therapy. Research advances in the use of Cd-free QDs for nanomedicine applications are discussed, including drug/gene delivery, protein/peptide delivery, image-guided surgery, diagnostics, and medical devices. The review then considers the pharmacokinetics and biodistribution of Cd-free QDs and summarizes current studies on the in vitro and in vivo toxicity of Cd-free QDs. Finally, we provide perspectives on the overall current status, challenges, and future directions in this field.

Optical Micro/Nanofiber-Based Localized Surface Plasmon Resonance Biosensors: Fiber Diameter Dependence.

Integration of functional nanomaterials with optical micro/nanofibers (OMNFs) can bring about novel optical properties and provide a versatile platform for various sensing applications. OMNFs as the key element, however, have seldom been investigated. Here, we focus on the optimization of fiber diameter by taking micro/nanofiber-based localized surface plasmon resonance sensors as a model. We systematically study the dependence of fiber diameter on the sensing performance of such sensors. Both theoretical and experimental results show that, by reducing fiber diameter, the refractive index sensitivity can be significantly increased. Then, we demonstrate the biosensing capability of the optimized sensor for streptavidin detection and achieve a detection limit of 1 pg/mL. Furthermore, the proposed theoretical model is applicable to other nanomaterials and OMNF-based sensing schemes for performance optimization.

Multifunctional Hyperbolic Nanogroove Metasurface for Submolecular Detection.

Metasurface serves as a promising plasmonic sensing platform for engineering the enhanced light-matter interactions. Here, a hyperbolic metasurface with the nanogroove structure in the subwavelength scale is designed. This metasurface is able to modify the wavefront and wavelength of surface plasmon wave with the variation of the nanogroove width or periodicity. At the specific optical frequency, surface plasmon polaritons are tightly confined and propagated with a diffraction-free feature due to the epsilon-near-zero effect. Most importantly, the groove hyperbolic metasurface can enhance the plasmonic sensing with an ultrahigh phase sensitivity of 30 373 deg RIU-1 and Goos-Hänchen shift sensitivity of 10.134 mm RIU-1 . The detection resolution for refractive index change of glycerol solution is achieved as 10-8 RIU based on the phase measurement. The detection limit of bovine serum albumin (BSA) molecule is measured as low as 0.1 × 10-18 m (1 × 10-19 mol L-1 ), which corresponds to a submolecular detection level (0.13 BSA mm-2 ). As for low-weight biotin molecule, the detection limit is estimated below 1 × 10-15 m (1 × 10-15 mol L-1 , 1300 biotin mm-2 ). This enhanced plasmonic sensing performance is two orders of magnitude higher than those with current state-of-art plasmonic metamaterials and metasurfaces.

Hydrogen evolution based on the electrons/protons stored on amorphous TiO2.

The hydrogen evolution reaction (HER) using recyclable mediator is being actively pursued as a route for solar energy conversion. Herein, we introduce a catalyst mediator (MoS2) that enables proton-coupled electron transfer (PCET) process on the recyclable TiO2 (H+-TiO2/e-) to a separate, catalytic hydrogen production step without requiring post-light energy input. This approach supplies a new insight to hydrogen evolution with the recyclable proton-electron pairs, stored at the semiconductor after the light irradiation. It was found that 80% of the electrons stored on TiO2 could be devoted to the reduction of H+ into H2 on MoS2 nanosheets in the dark. The electron transfer to MoS2 occurs at a rate of 455 µmol h-1 g-1 and 947 µmol h-1 g-1 in the dark and excited state, respectively.

Nanomaterials enhanced surface plasmon resonance for biological and chemical sensing applications.

The main challenge for all electrical, mechanical and optical sensors is to detect low molecular weight (less than 400 Da) chemical and biological analytes under extremely dilute conditions. Surface plasmon resonance sensors are the most commonly used optical sensors due to their unique ability for real-time monitoring the molecular binding events. However, their sensitivities are insufficient to detect trace amounts of small molecular weight molecules such as cancer biomarkers, hormones, antibiotics, insecticides, and explosive materials which are respectively important for early-stage disease diagnosis, food quality control, environmental monitoring, and homeland security protection. With the rapid development of nanotechnology in the past few years, nanomaterials-enhanced surface plasmon resonance sensors have been developed and used as effective tools to sense hard-to-detect molecules within the concentration range between pmol and amol. In this review article, we reviewed and discussed the latest trend and challenges in engineering and applications of nanomaterials-enhanced surface plasmon resonance sensors (e.g., metallic nanoparticles, magnetic nanoparticles, carbon-based nanomaterials, latex nanoparticles and liposome nanoparticles) for detecting "hard-to-identify" biological and chemical analytes. Such information will be viable in terms of providing a useful platform for designing future ultrasensitive plasmonic nanosensors.

Preparation of biofunctionalized quantum dots using microfluidic chips for bioimaging.

Biofunctionalized quantum dots (QDs), especially protein-coated QDs, are known to be useful targeted fluorescent labels for cellular and deep-tissue imaging. These nanoparticles can also serve as efficient energy donors in fluorescence resonance energy transfer (FRET) binding assays for the multiplexed sensing of tumor markers. However, current preparation processes for protein-functionalized QDs are laborious and require multiple synthesis steps (e.g. preparing them in high temperature, making them dispersible in water, and functionalizing them with surface ligands) to obtain a high quality and quantity of QD formulations, significantly impeding the progress of employing QDs for clinical diagnostics use such as a QD-based immunohistofluorescence assay. Herein, we demonstrate a one-step synthesis approach for preparing protein-functionalized QDs using a microfluidic (MF) chip setup. Using bovine serum albumin (BSA) molecules as the surface ligand model, we first studied and optimized the MF reaction synthesis parameters (e.g. reaction temperature, and channel width and length) for making protein-functionalized QDs using COMSOL simulation modeling, followed by experimental verification. Moreover, in comparison with the BSA-functionalized QDs synthesized using the conventional bench-top method, BSA-QDs prepared using the MF approach exhibit a significantly higher protein-functionalization efficiency, photostability and colloidal stability. The proposed one-step MF synthesis approach provides a rapid, cost effective, and a small-scale production of nanocrystals platform for developing new QD formulations in applications ranging from cell labeling to biomolecular sensing. Most importantly, this approach will considerably reduce the amount of chemical waste generated during the trial-and-error stage of developing and perfecting the desired physical and optical properties of new QD materials.

Label-free biosensing with singular-phase-enhanced lateral position shift based on atomically thin plasmonic nanomaterials.

Rapid plasmonic biosensing has attracted wide attention in early disease diagnosis and molecular biology research. However, it was still challenging for conventional angle-interrogating plasmonic sensors to obtain higher sensitivity without secondary amplifying labels such as plasmonic nanoparticles. To address this issue, we developed a plasmonic biosensor based on the enhanced lateral position shift by phase singularity. Such singularity presents as a sudden phase retardation at the dark point of reflection from resonating plasmonic substrate, leading to a giant position shift on reflected beam. Herein, for the first time, the atomically thin layer of Ge2Sb2Te5 (GST) on silver nanofilm was demonstrated as a novel phase-response-enhancing plasmonic material. The GST layer was not only precisely engineered to singularize phase change but also served as a protective layer for active silver nanofilm. This new configuration has achieved a record-breaking largest position shift of 439.3 µm measured in calibration experiments with an ultra-high sensitivity of 1.72 × 108 nm RIU-1 (refractive index unit). The detection limit was determined to be 6.97 × 10-7 RIU with a 0.12 µm position resolution. Besides, a large figure of merit (FOM) of 4.54 × 1011 µm (RIU∙°)-1 was evaluated for such position shift interrogation, enabling the labelfree detection of trace amounts of biomolecules. In targeted biosensing experiments, the optimized sensor has successfully detected small cytokine biomarkers (TNF-α and IL-6) with the lowest concentration of 1 × 10-16 M. These two molecules are the key proinflammatory cancer markers in clinical diagnosis, which cannot be directly screened by current clinical techniques. To further validate the selectivity of our sensing systems, we also measured the affinity of integrin binding to arginylglycylaspartic acid (RGD) peptide (a key protein interaction in cell adhesion) with different Mn2+ ion concentrations, ranging from 1 nM to 1 mM.

Porous carbon film/WO3-x nanosheets based SERS substrate combined with deep learning technique for molecule detection.

The Surface-enhanced Raman scattering (SERS) is an attractive optical detecting method with high sensitivity and detectivity, however challenges on large-area signal uniformity and complex spectra analysis methods always retards its wide application. Herein, a highly sensitive and uniform SERS detection strategy supported by porous carbon film/WO3-x nanosheets (PorC/WO3-x) based noble-metal-free SERS substrate and deep learning algorithm are reported. Experimentally, the PorC/WO3-x substrate was prepared by high-temperature annealing the PorC/WO3 films under the argon atmosphere. The defect density of the WO3 was controlled by tuning the reducing reaction time during the annealing process. The SERS performance was evaluated by using R6G as the Raman reporter, it showed that the SERS intensity obtained on the substrate with the optimal annealing time of 3 h was about 8 times as high as that obtained on the PorC/WO3 substrate without annealing treatment. And detection limit of 10-7 M and Raman enhancement factor of 106 could be achieved. Moreover, the above optimal SERS substrate was utilized to detect flavonoids of quercetin, 3-hydroxyflavone and flavone, and a deep learning algorithms was incorporated to identify the quercetin. It revealed that quercetin can be accurately detected within the above flavonoids, and lowest detectable concentration of 10-5 M can be achieved.

Asymmetrical Dimer Photonic Crystals Enabling Outstanding Optical Sensing Performance.

The exploration of the propensity of engineered materials to bring forward innovations predicated on their periodic nanostructured tailoring rather than the features of their individual compounds is a continuous pursuit that has propelled optical sensors to the forefront of ultra-sensitive bio-identification. Herein, a numerical analysis based on the Finite Element Method (FEM) was used to investigate and optimize the optical properties of a unidirectional asymmetric dimer photonic crystal (PhC). The proposed device has many advantages from a nanofabrication standpoint compared to conventional PhCs sensors, where integrating defects within the periodic array is imperative. The eigenvalue and transmission analysis performed indicate the presence of a protected, confined mode within the structure, resulting in a Fano-like response in the prohibited states. The optical sensor demonstrated a promising prospect for monitoring the DNA hybridization process, with a quality factor (QF) of roughly 1.53×105 and a detection limit (DL) of 4.4×10-5 RIU. Moreover, this approach is easily scalable in size while keeping the same attributes, which may potentially enable gaze monitoring.

Rapid Prototyping of Multi-Functional and Biocompatible Parafilm®-Based Microfluidic Devices by Laser Ablation and Thermal Bonding.

In this paper, we report a simple, rapid, low-cost, biocompatible, and detachable microfluidic chip fabrication method for customized designs based on Parafilm®. Here, Parafilm® works as both a bonding agent and a functional membrane. Its high ultimate tensile stress (3.94 MPa) allows the demonstration of high-performance actuators such as microvalves and micropumps. By laser ablation and the one-step bonding of multiple layers, 3D structured microfluidic chips were successfully fabricated within 2 h. The consumption time of this method (~2 h) was 12 times less than conventional photolithography (~24 h). Moreover, the shear stress of the PMMA-Parafilm®-PMMA specimens (0.24 MPa) was 2.13 times higher than that of the PDMS-PDMS specimens (0.08 MPa), and 0.56 times higher than that of the PDMS-Glass specimens (0.16 MPa), showing better stability and reliability. In this method, multiple easily accessible materials such as polymethylmethacrylate (PMMA), PVC, and glass slides were demonstrated and well-incorporated as our substrates. Practical actuation devices that required high bonding strength including microvalves and micropumps were fabricated by this method with high performance. Moreover, the biocompatibility of the Parafilm®-based microfluidic devices was validated through a seven-day E. coli cultivation. This reported fabrication scheme will provide a versatile platform for biochemical applications and point-of-care diagnostics.

Two-dimensional nanomaterials as enhanced surface plasmon resonance sensing platforms: Design perspectives and illustrative applications.

Both increasing demand for ultrasensitive detection in the scientific community and significant new breakthroughs in materials science field have inspired and promoted the development of new-generation multifunctional plasmonic sensing platforms by adopting promising plasmonic nanomaterials. Recently, high-quality surface plasmon resonance (SPR) sensors, assisted by two dimensional (2D) nanomaterials including 2D van der Waals (vdWs) materials (such as graphene/graphene oxide, transition metal dichalcogenides (TMDs), phosphorene, antimonene, tellurene, MXenes, and metal oxides), 2D metal-organic frameworks (MOFs), 2D hyperbolic metamaterials (HMMs), and 2D optical metasurfaces, have emerged as a class of novel plasmonic sensing platforms that show unprecedented detection sensitivity and impressive performance. This review of recent progress in 2D nanomaterials-enhanced SPR platforms will highlight their compelling plasmonic enhancement features, working mechanisms, and design methodologies, as well as discuss illustrative practical applications. Hence, it is of great importance to describe the latest research progress in 2D nanomaterials-enhanced SPR sensing cases. In this review, we present some concepts of SPR enhanced by 2D nanomaterials, including the basic principles of SPR, signal modulation approaches, and working enhancement mechanisms for various 2D materials-enhanced SPR systems. In addition, we also demonstrate a detailed categorization of 2D nanomaterials-enhanced SPR sensing platforms and comment on their ability to realize ultrasensitive SPR detection. Finally, we conclude with future perspectives for exploring a new generation of 2D nanomaterials-based sensors.

Ag NC and Ag NP/PorC Film-Based Surface-Enhanced Raman Spectroscopy-Type Immunoassay for Ultrasensitive Prostate-Specific Antigen Detection.

Surface-enhanced Raman scattering (SERS) is a spectral detection technology with high sensitivity and detectivity and can be used to detect the fingerprint information of the molecules with ultralow concentration. Herein, a kind of immunostructure constructed by Ag nanoparticle/porous carbon (Ag NP/PorC) films as the immunosubstrate and Ag NCs as the immunoprobes was presented for ultralow level prostate-specific antigen (PSA) detection. Experimentally, the Ag NP/PorC film was first prepared with a facile method by carbonizing the gelatin-AgNO3 film in air, and Ag NCs were synthesized by the hydrothermal method. Then, the Ag NP/PorC film was modified by PSA antibodies as the substrate, while Ag NCs were decorated by R6G and PSA antibodies for probes. The sandwiched SERS detection embodiment was constructed by the immunoreaction between the PSA and PSA antibody predecorated on the substrate and probes. Our results show that the proposed SERS-type immunoassay is highly sensitive and selective to a wide range of PSA concentrations from 10-5 to 10-12 g/mL. Thereafter, it was also implemented to detect the PSA level in human serum, and the results successfully reproduce the PSA levels as those measured by the chemiluminescence method with a recovery rate above 90%. All in all, this SERS-type immunoassay provides a promising method for the early diagnosis of prostate cancer.