Real-time and in-situ monitoring of Abrin induced cell apoptosis by using SERS spectroscopy

Nanomaterials meet surface-enhanced Raman scattering towards enhanced clinical diagnosis: a review

Surface-enhanced Raman scattering (SERS) is a very promising tool for the direct detection of biomarkers for the diagnosis of i.e., cancer and pathogens. Yet, current SERS strategies are hampered by non-specific interactions with co-existing substances in the biological matrices and the difficulties of obtaining molecular fingerprint information from the complex vibrational spectrum. Raman signal enhancement is necessary, along with convenient surface modification and machine-based learning to address the former issues. This review aims to describe recent advances and prospects in SERS-based approaches for cancer and pathogens diagnosis. First, direct SERS strategies for key biomarker sensing, including the use of substrates such as plasmonic, semiconductor structures, and 3D order nanostructures for signal enhancement will be discussed. Secondly, we will illustrate recent advances for indirect diagnosis using active nanomaterials, Raman reporters, and specific capture elements as SERS tags. Thirdly, critical challenges for translating the potential of the SERS sensing techniques into clinical applications via machine learning and portable instrumentation will be described. The unique nature and integrated sensing capabilities of SERS provide great promise for early cancer diagnosis or fast pathogens detection, reducing sanitary costs but most importantly allowing disease prevention and decreasing mortality rates.

A New Method for Abrin Detection Based on the Interaction between Target Molecules and Fluorescently Labeled Aptamers on Magnetic Microspheres

A quantitative structure-activity relationship (QSAR) model for the structure and affinity of abrin aptamers was established. A higher affinity abrin aptamer based on the established QSAR model was screened by site-directed mutagenesis. The fluorescence quenching effect between magnetic microspheres and fluorescent molecules was studied for the first time. A new method for abrin detection based on the interaction between target molecules and fluorescently labeled aptamers on magnetic microspheres was developed, with the detection limit of 5 ng mL^-1. This method can overcome the influence of complex environmental interferents in abrin detection and can meet the analysis requirements for simulated samples such as water, soil, and food.

Surface-enhanced Raman scattering: An emerging tool for sensing cellular function

Continuous long-term intracellular imaging and multiplexed monitoring of biomolecular changes associated with key cellular processes remains a challenge for the scientific community. Recently, surface-enhanced Raman scattering (SERS) has been demonstrated as a powerful spectroscopic tool in the field of biology owing to its significant advantages. Some of these include the ability to provide molecule-specific information with exquisite sensitivity, working with small volumes of precious samples, real-time monitoring, and optimal optical contrast. More importantly, the availability of a large number of novel Raman reporters with narrower full width at half maximum (FWHM) of spectral peaks/vibrational modes than conventional fluorophores has created a versatile palette of SERS-based probes that allow targeted multiplex sensing surpassing the detection sensitivity of even fluorescent probes. Due to its nondestructive nature, its applicability has been recognized for biological sensing, molecular imaging, and dynamic monitoring of complex intracellular processes. We critically discuss recent developments in this area with a focus on different applications where SERS has been used for obtaining information that remains elusive for conventional imaging methods. Current reports indicate that SERS has made significant inroads in the field of biology and has the potential to be used for in vivo human applications. This article is categorized under: Diagnostic Tools > In Vitro Nanoparticle-Based Sensing Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Surface enhanced Raman scattering for probing cellular biochemistry

Surface enhanced Raman scattering (SERS) from biomolecules in living cells enables the sensitive, but also very selective, probing of their biochemical composition. This minireview discusses the developments of SERS probing in cells over the past years from the proof-of-principle to observe a biochemical status to the characterization of molecule-nanostructure and molecule-molecule interactions and cellular processes that involve a wide variety of biomolecules and cellular compartments. Progress in applying SERS as a bioanalytical tool in living cells, to gain a better understanding of cellular physiology and to harness the selectivity of SERS, has been achieved by a combination of live cell SERS with several different approaches. They range from organelle targeting, spectroscopy of relevant molecular models, and the optimization of plasmonic nanostructures to the application of machine learning and help us to unify the information from defined biomolecules and from the cell as an extremely complex system.

Transparent and flexible AuNSs/PDMS-based SERS substrates for in-situ detection of pesticide residues

Herein, we developed a PDMS-based flexible SERS substrate modified with gold nanostars (AuNSs) for in-situ detection of pesticide residues on fruit surfaces. AuNSs with sharp branches were assembled on aminated PDMS membrane by chemical bonding effect. The AuNSs/PDMS substrate showed good signal uniformity, stability and sensitivity using the Raman signal molecule 4-MBA and the detection concentration of 4-MBA was as low as 10^-8 mol/L. Then the AuNSs/PDMS substrate was used to detect methyl parathion (MP) standard solution. A good linear relationship between SERS intensity at 1342 cm^-1 and MP concentration was established in the range of 4 μg/mL-100 μg/mL, and the limit of detection was down to 1.946 μg/mL. Moreover, the AuNSs/PDMS substrate was directly covered on the surface of MP contaminated apple, and the Raman laser was incident from the back of substrate to achieve in-situ detection of pesticide residues. The recovery ratio indicated that the fabricated SERS substrate was realized successfully in real sample detection. AuNSs/PDMS substrate eliminates the requirement for sample pre-processing steps before testing, which can be used as a method for rapid inspection of pesticide in agricultural products on site.

A review of surface-enhanced Raman spectroscopy in pathological processes

With the continuous growth of the human population and new challenges in the quality of life, it is more important than ever to diagnose diseases and pathologies with high accuracy, sensitivity and in different scenarios from medical implants to the operation room. Although conventional methods of diagnosis revolutionized healthcare, alternative analytical methods are making their way out of academic labs into clinics. In this regard, surface-enhanced Raman spectroscopy (SERS) developed immensely with its capability to achieve single-molecule sensitivity and high-specificity in the last two decades, and now it is well on its way to join the arsenal of physicians. This review discusses how SERS is becoming an essential tool for the clinical investigation of pathologies including inflammation, infections, necrosis/apoptosis, hypoxia, and tumors. We critically discuss the strategies reported so far in nanoparticle assembly, functionalization, non-metallic substrates, colloidal solutions and how these techniques improve SERS characteristics during pathology diagnoses like sensitivity, selectivity, and detection limit. Moreover, it is crucial to introduce the most recent developments and future perspectives of SERS as a biomedical analytical method. We finally discuss the challenges that remain as bottlenecks for a routine SERS implementation in the medical room from in vitro to in vivo applications. The review showcases the adaptability and versatility of SERS to resolve pathological processes by covering various experimental and analytical methods and the specific spectral features and analysis results achieved by these methods.

Elucidating Gold-MnO2 Core-Shell Nanoenvelope for Real Time SERS-Guided Photothermal Therapy on Pancreatic Cancer Cells

Pancreatic cancer represents one of the most aggressive in nature with a miserable prognosis that warrants efficient diagnostic and therapeutic interventions. Herein, a MnO₂ overlaid gold nanoparticle (AuNPs) based photothermal theranostic nanoenvelope (PTTNe:MnO₂@AuNPs) was fabricated to substantiate surface-enhanced Raman spectroscopy (SERS) guided real-time monitoring of photothermal therapy (PTT) in pancreatic cancer cells. A sharp enhancement of the fingerprint Raman signature of MnO₂ at 569 cm^-1 exhibited as a marker peak for the first time to elucidate the intracellular PTT event. In this strategic design, the leftover bare AuNPs after the degradation of the MnO₂ layer from the nanoenvelope in the presence of intracellular H₂O₂ enabled real-time tracking of biomolecular changes of Raman spectral variations during PTT. Moreover, the surface of the as-synthesized nanoenvelope was functionalized with a pancreatic cancer cell targeting peptide sequence for cholecystokinin fashioned the PTTNe with admirable stability and biocompatibility. Finally, the precise cell death mechanism was explicitly assessed by SERS spectral analysis as a complementary technique. This targeted phototheranostic approach demonstrated in pancreatic cancer cells presented a therapeutically viable prototype for futuristic personalized cancer nanomedicine.

Physical seed dormancy in Abrus precatorious (Ratti): a scientific validation of indigenous technique

Seeds of Abrus precatorius L. (Fabaceae) were used as weight measure by Indigenous people. Where, the seeds were referred as Ratti; a traditional Indian unit of mass measurement. Seed weight fluctuates depending upon age, moisture, storage-period/conditions. Therefore, use of seeds as a weighing unit become dubious and need to be validated. For this purpose, seeds of A. precatorious were subjected to different moisture conditions and periodically monitored. Surprisingly, there was no change in seed weight was observed, indicating the impermeability of seed coat. The later was confirmed by scarification of seed coat which resulted in 53% increase in seed weight against 0% in control. Further, presence of a potent toxin (abrin) in the seed coat protects it from pests and microbes, and contributes to the maintenance of impermeability for longer period of time. The data validates the use of A. precatorious seeds as a weighing unit (ratti) by the indigenous people and discussed.

Microextraction based on microplastic followed by SERS for on-site detection of hydrophobic organic contaminants, an indicator of seawater pollution

Microplastics (MPs) have been proven to concentrate hydrophobic organic contaminants (HOCs) from seawater as the sorbent phase, and the concentration of HOCs in aqueous solutions could be estimated from MPs preloaded with HOCs by equilibrium partition coefficient. This study firstly proposed to in situ quantify fluoranthene (a representative HOCs) pre-concentrated on MPs using surface enhance raman scattering (SERS) in combination with mathematical models, as an efficient monitoring tool for fluoranthene pollution in the aquatic environment. AgNPs-coated quartz (AgNPs@SiO2) substrate was fabricated. The SERS substrate was tested using fluoranthene standard solution with the minimal detectable concentration of 1 ng/mL achieved. Applying SERS for the detection of fluoranthene sorbed on MPs, the detection limit of fluoranthene on MPs was 3.3 ng/g, where the concentration in the corresponding equilibrium seawater was 0.97 ng/mL. Since more than one fluoranthene peak was observed, the quantitative detection was investigated by interval partial least square model. Eight characteristic peak ranges were selected to develop the model for predicting fluoranthene concentration, with R²c and R²v of 0.90 and 0.82, respectively. The study provides a promising solution to monitor trace level of contaminations in aquatic environment, using MPs as the passive sampler.

Real-time monitoring of multicomponent reactive dye adsorption on cotton fabrics by Raman spectroscopy

Accurate real-time determination of each dye in combination dyeing is critical to the control of dyeing process, which plays an important role in upgrading the dyeing techniques of textile. In this work, Raman spectroscopy was applied to dyeing baths containing multiple dye species of varying structures to quantitatively monitor the dyeing process of each individual dye. Quantitative models were successfully established by partial least squares (PLS) for all combinations of the nine commonly used reactive dyes studied. The correlation coefficients were greater than 0.99, the root mean squared errors of calibration (RMSEC) were less than 0.2650 and the root mean squared errors of prediction (RMSEP) were less than 0.1340, even for the three-component mixture of Reactive Red 239 (RR239), Reactive Yellow 176 (RY176) and Reactive Blue 194 (RB194), which are similar in structures. The model was shown to be valid in the presence of added electrolytes (sodium sulfates). Real-time adsorption monitoring based on the model revealed that the dyes interacted with one another and competed for active sites. The adsorption kinetics obtained by Raman analysis shed light on dye compatibility and could be used to guide the design of dyeing recipe and dyeing process for optimum color reproduction. In addition, in situ monitoring by Raman spectroscopy maybe integrated with real-time on line control of dyeing parameters for fully automated production of dyed fabrics.

Study on the precise mechanism of Mitoxantrone-induced Jurkat cell apoptosis using surface enhanced Raman scattering

Mitoxantrone (MTX), one representative of anthraquinone ring anticancer drugs, reveals excellent anticancer effects in acute leukemia. Though current studies have shown that MTX-induced acute leukemia cell apoptosis is implemented by inserting into DNA, and then leading to DNA breakage and the subsequent transcription termination, but the specific location information of MTX embedded in DNA remains unknown. In this study, combining surface enhanced Raman scattering (SERS) and principal component analysis (PCA), we achieve the biochemical changes of MTX-induced Jurkat cell apoptosis and the location information of MTX embedded in DNA. In contrast, we also present the corresponding result of Daunorubicin (DNR)-induced Jurkat cell apoptosis. It is found that the location of MTX embedded in DNA of Jurkat cell is different from DNR, in which the action site of MTX is mainly implemented by blocking and destroying AT base pairs while DNR is performed by embedding and destroying GC base pairs and then the base A. Clearly, this achieved information is very useful for the designing and modification of anthraquinone ring anticancer drugs.

Synthesis of corrugated surface AgNWs and their applications in surface enhanced Raman spectroscopy

Among metals, AgNWs are considered to be excellent materials for use in surface enhancement Raman spectroscopic (SERS) sensing due to their superior electrical properties, strong electromagnetic field generation and strong enhancement intensity.

Influence of drugs on the prospective diagnostic method for coronary heart disease with urine

The morbidity of coronary heart disease (CHD) with high risks has been rising in recent years. A novel and noninvasive method based on surface-enhanced Raman spectroscopy (SERS) was proposed by Yang et al. (Analyst 143: 2235, 2018) to prospectively diagnose the arterial blockage by detecting platelet-derived growth factor-BB (PDGF-BB) in urine. Clinically, anti-platelet drugs (such as aspirin, statins and clopidogrel) are often used for ordinary CHD patients or patients with percutaneous coronary intervention (PCI). Therefore, whether the previous developed method can be applied to the CHD patients on long-term medication (more than 6 months) or post-PCI patients was investigated here. Firstly, urine samples of 13 CHD patients on long-term medication (aspirin, rosuvastatin, clopidogrel bisulfate) and 13 post-PCI patients were measured by the proposed method. Clinical data of coronary angiography results provided by Xin Hua Hospital and Yangpu District Central Hospital Antu Branch revealed that these 26 patients were with serious arterial blockage, however, characteristic Raman peak at 1509 cm^-1 attributed to PDGF-BB was not observed in the SERS spectra of these 26 patients. In addition, an eight-day follow-up investigation was performed on a CHD patient with PCI three years ago and on long-term medication. It was found that the Raman peak at 1509 cm^-1 could be only observed in the third and fourth day after suspending the drugs. Furthermore, SERS spectra of mixed solutions of PDGF-BB and aspirin, rosuvastatin, mixed solutions of these two drugs and clopidogrel bisulfate were analyzed. The Raman peak at 1509 cm^-1 was not found in all these spectra, it indicated that all the three kinds of drugs could influence on the SERS signal of PDGF-BB. Therefore, the previous developed method is not suitable for CHD patients on long-term medication and post-PCI patients.

True one cell chemical analysis: a review

The constantly growing field of True One Cell (TOC) analysis has provided important information on the direct chemical composition of various cells and cellular components.