C-reactive protein (CRP) is an acute phase reactant to be a marker of inflammation and has been correlated with the cardiac injury. An immunoassay was performed using anti-human CRP antibody on an InterDigitated electrode (IDE) sensor to determine and specify CRP concentration for diagnosing the condition of myocardial inflammation. To promote the detection, gold nanoparticle (GNP) was seeded on the aminated-IDE surface. Anti-CRP was hitched on the GNP-seeded surface and identified the abundance of CRP. The limit of quantification was found as 100 fM, and the higher current response was noticed by increasing CRP concentrations with the sensitivity at 1 pM. Furthermore, CRP-spiked human serum did not interfere the determination of CRP and increased the current response, indicating suitability for a real-life sample. Similarly, the control experiments with nonimmune antibody Troponin I are not showing the definite current responses, proving the selective identification of CRP. This method of diagnosing is needful to determine the cardiovascular injury at the right time.
In the present work, nanohybrid of an anticancer drug, doxorubicin (Dox) loaded gold-coated superparamagnetic iron oxide nanoparticles (SPIONs@Au) were prepared for a combination therapy of cancer by means of both hyperthermia and drug delivery. The Dox molecules were conjugated to SPIONs@Au nanoparticles with the help of cysteamine (Cyst) as a non-covalent space linker and the Dox loading efficiency was investigated to be as high as 0.32 mg/mg. Thus synthesized particles were characterized by HRTEM, UV-Vis, FT-IR, SQUID magnetic studies and further tested for heat and drug release at low frequency oscillatory magnetic fields. The hyperthermia studies investigated to be strongly influenced by the applied frequency and the solvents used. The Dox delivery studies indicated that the drug release efficacy is strongly improved by maintaining the acidic pH conditions and the oscillatory magnetic fields, i.e. an enhancement in the Dox release was observed from the oscillation of particles due to the applied frequency, and is not effected by heating of the solution. Finally, the in vitro cell viability and proliferation studies were conducted using two different immortalized cell lines containing a cancerous (MCF-7 breast cancer) and non-cancerous H9c2 cardiac cell type.
In the present study, the construction of arrays on silicon for naked-eye detection of DNA dengue was demonstrated. The array was created by exposing a polyethylene glycol (PEG) silane monolayer to 254 nm ultraviolet (UV) light through a photomask. Formation of the PEG silane monolayer and photomodifed surface properties was thoroughly characterized by using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results of XPS confirmed that irradiation of ultraviolet (UV) light generates an aldehyde functional group that offers conjugation sites of amino DNA probe for detection of a specific dengue virus target DNA. Employing a gold enhancement process after inducing the electrostatic interaction between positively charged gold nanoparticles and the negatively charged target DNA hybridized to the DNA capture probe allowed to visualize the array with naked eye. The developed arrays demonstrated excellent performance in diagnosis of dengue with a detection limit as low as 10 pM. The selectivity of DNA arrays was also examined using a single base mismatch and noncomplementary target DNA.
A microring resonator (MRRs) system incorporated with a add/drop filter is proposed in which ultra-short single, multi-temporal, and spatial optical soliton pulses are simulated and used to kill abnormal cells, tumors, and cancer. Chaotic signals are generated by a bright soliton pulse within a nonlinear MRRs system. Gold nanoparticles and ultra-short femtosecond/picosecond laser pulses' interaction holds great interest in laser nanomedicine. By using appropriate soliton input power and MRRs parameters, desired spatial and temporal signals can be generated over the spectrum. Results show that short temporal and spatial solitons pulse with FWHM = 712 fs and FWHM = 17.5 pm could be generated. The add/drop filter system is used to generate the high-capacity, ultra-short soliton pulses in the range of nanometer/second and picometer/second.
A new optical trapping design to transport gold nanoparticles using a PANDA ring resonator system is proposed. Intense optical fields in the form of dark solitons controlled by Gaussian pulses are used to trap and transport nanoscopic volumes of matter to the desired destination via an optical waveguide. Theoretically, the gradient and scattering forces are responsible for this trapping phenomenon, where in practice such systems can be fabricated and a thin-film device formed on the specific artificial medical materials, for instance, an artificial bone. The dynamic behavior of the tweezers can be tuned by controlling the optical pulse input power and parameters of the ring resonator system. Different trap sizes can be generated to trap different gold nanoparticles sizes, which is useful for gold nanoparticle therapy. In this paper, we have shown the utility of gold nanoparticle trapping and delivery for therapy, which may be useful for cosmetic therapy and related applications.
A fluorometric assay is described for highly sensitive quantification of Escherichia coli O157:H7. Reporter oligos were immobilized on graphene quantum dots (GQDs), and quencher oligos were immobilized on gold nanoparticles (AuNPs). Target DNA was co-hybridized with reporter oligos on the GQDs and quencher oligos on AuNPs. This triggers quenching of fluorescence (with excitation/emission peaks at 400 nm/530 nm). On introducing target into the system, fluorescence is quenched by up to 95% by 100 nM concentrations of target oligos having 20 bp. The response to the fliC gene of E. coli O157:H7 increases with the logarithm of the concentration in the range from 0.1 nM to 150 nM. The limit of detection is 1.1 ± 0.6 nM for n = 3. The selectivity and specificity of the assay was confirmed by evaluating the various oligos sequences and PCR product (fliC gene) amplified from genomic DNA of the food samples spiked with E. coli O157:H7. Graphical abstractSchematic representation of fluorometric assay for highly sensitive quantification of Escherichia coli O157:H7 based on fluorescence quenching gene assay for fliC gene of E. coli O157:H7.
Early detection and efficient treatment of cancer disease remains a drastic challenge in 21st century. Throughout the bulk of funds, studies, and current therapeutics, cancer seems to aggressively advance with drug resistance strains and recurrence rates. Nevertheless, nanotechnologies have indeed given hope to be the next generation for oncology applications. According to US National cancer institute, it is anticipated to revolutionize the perspectives of cancer diagnosis and therapy. With such success, nano-hybrid strategy creates a marvelous preference. Herein, graphene-gold based composites are being increasingly studied in the field of oncology, for their outstanding performance as robust vehicle of therapeutic agents, built-in optical diagnostic features, and functionality as theranostic system. Additional modes of treatments are also applicable including photothermal, photodynamic, as well as combined therapy. This review aims to demonstrate the various cancer-related applications of graphene-gold based hybrids in terms of detection and therapy, highlighting the major attributes that led to designate such system as a promising ally in the war against cancer.
In the field of diagnostics, molecular amplification targeting unique genetic signature sequences has been widely used for rapid identification of infectious agents, which significantly aids physicians in determining the choice of treatment as well as providing important epidemiological data for surveillance and disease control assessment. We report the development of a rapid nucleic acid lateral flow biosensor (NALFB) in a dry-reagent strip format for the sequence-specific detection of single-stranded polymerase chain reaction (PCR) amplicons at ambient temperature (22-25°C). The NALFB was developed in combination with a linear-after-the-exponential PCR assay and the applicability of this biosensor was demonstrated through detection of the cholera toxin gene from diarrheal-causing toxigenic Vibrio cholerae. Amplification using the advanced asymmetric PCR boosts the production of fluorescein-labeled single-stranded amplicons, allowing capture probes immobilized on the NALFB to hybridize specifically with complementary targets in situ on the strip. Subsequent visual formation of red lines is achieved through the binding of conjugated gold nanoparticles to the fluorescein label of the captured amplicons. The visual detection limit observed with synthetic target DNA was 0.3 ng and 1 pg with pure genomic DNA. Evaluation of the NALFB with 164 strains of V. cholerae and non-V. cholerae bacteria recorded 100% for both sensitivity and specificity. The whole procedure of the low-cost NALFB, which is performed at ambient temperature, eliminates the need for preheated buffers or additional equipment, greatly simplifying the protocol for sequence-specific PCR amplicon analysis.
We developed a multiplex enzyme-based electrochemical genosensor for sequence-specific detection of multiplex linear-after-the-exponential-PCR amplicons that targeted toxigenic Vibrio cholerae O1 and O139 using novel screen-printed gold electrode bisensors.
A novel enzyme/nanoparticle-based DNA biosensing platform with dual colorimetric/electrochemical approach has been developed for the sequence-specific detection of the bacterium Vibrio cholerae, the causative agent of acute diarrheal disease in cholera. This assay platform exploits the use of shelf-stable and ready-to-use (shelf-ready) reagents to greatly simplify the bioanalysis procedures, allowing the assay platform to be more amenable to point-of-care applications. To assure maximum diagnosis reliability, an internal control (IC) capable of providing instant validation of results was incorporated into the assay. The microbial target, single-stranded DNA amplified with asymmetric PCR, was quantitatively detected via electrochemical stripping analysis of gold nanoparticle-loaded latex microspheres as a signal-amplified hybridization tag, while the incorporated IC was analyzed using a simplified horseradish peroxidase enzyme-based colorimetric scheme by simple visual observation of enzymatic color development. The platform showed excellent diagnostic sensitivity and specificity (100%) when challenged with 145 clinical isolate-spiked fecal specimens. The limits of detection were 0.5ng/ml of genomic DNA and 10 colony-forming units (CFU)/ml of bacterial cells with dynamic ranges of 0-100ng/ml (R(2)=0.992) and log10 (1-10(4) CFU/ml) (R(2)=0.9918), respectively. An accelerated stability test revealed that the assay reagents were stable at temperatures of 4-37°C, with an estimated ambient shelf life of 200 days. The versatility of the biosensing platform makes it easily adaptable for quantitative detection of other microbial pathogens.
The urinary C-terminal telopeptide fragment of type II collagen (uCTX-II) has been reported as the efficient blood-based biomarker for osteoarthritis, which affects knees, hands, spine, and hips. This study reports a sensing strategy with antibody-conjugated gold nanoparticles (GNP) on an interdigitated electrode (IDE) to determine uCTX-II. The GNP-antibody complex was chemically immobilized on the IDE surface through the amine linker. uCTX-II was determined by monitoring the alteration in current upon interacting the GNP-complexed antibody. This strategy was improved the detection by attracting higher uCTX-II molecules, and the detection limit falls in the range of 10-100 pM with an acceptable regression value [y = 0.6254x - 0.4073, R² = 0.9787]. The sensitivity of the detection was recognized at 10 pM. Additionally, upon increasing the uCTX-II concentration, the current changes were increased in a linear fashion. Control detection with nonimmune antibody and control protein do not increase the current level, confirming the specific detection of uCTX-II. This method of detection helps in diagnosing osteoarthritis and its follow-up treatment.
Gestational diabetes (hyperglycaemia) is an elevated blood sugar level diagnosed during the period of pregnancy and affects the baby's health. Hyperglycaemia has been found within the gestational weeks between 24 and 28, and the foetus has also the possibility of getting out prior to this test frame; it causes excessive birth weight, early birth, low-blood sugar level, respiratory distress syndrome, and type-2 diabetes to the mother. It creates a mandatory situation to identify the hyperglycaemia at least during the pregnancy weeks from 18 to 20. Further, a continuous monitoring of the level of glucose is necessary for the proper delivery. In this work, a method is introduced for glucose detection at 0.06 mg/mL, assisted by gold nanorod (GNR)-conjugated glucose oxidase (GOx) on interdigitated electrode sensor. In the absence of GNR, GOx shows the limit of glucose detection to be 0.25 mg/mL. Moreover, with GOx-GNR the reactions of all the glucose concentrations have recorded higher levels of the current from the baseline. With the specificity analysis, it was found that the glucose only reacts with GOx-GNR and discriminates other sugars efficiently. This method of detection is useful to diagnose and continuously monitor the glucose level during the pregnancy period.
Human papilloma virus (HPV) affects predominantly the genital area, which includes vagina, cervix, penis, vulva scrotum, rectum and anus. Among 100 types of HPV, 14 types are considered to cause the risky cancer. The gene HPV-16 E7 is responsible for the development of cancer with the infected women. Earlier identification of this gene sequence avoids the cancer progression. The targeted HPV-16 E7 sequence was sandwiched by capture and reporter sequences on the carbodiimidazole-modified interdigitated electrode (IDE) surface. Target sequence at 100 f. was paired to the capture sequence immobilized on IDE sensing surface. To this surface, different concentrations of reporter sequence with and without gold rod (GNR) were evaluated. In both cases the detections were attained 1 aM by the reporter sequence pairing and with GNR increments in current were found. This enhancement was found to be 1000 folds, considering the condition was revealed in the absence of reporter. This sandwich detection strategy of capture-target-reporter sequences for HPV-16 detection on the IDE sensing surface helps to diagnose the association of cervical cancer.
In nucleic acid testing (NAT), gold nanoparticle (AuNP)-based lateral flow assays (LFAs) have received significant attention due to their cost-effectiveness, rapidity, and the ability to produce a simple colorimetric readout. However, the poor sensitivity of AuNP-based LFAs limits its widespread applications. Even though various efforts have been made to improve the assay sensitivity, most methods are inappropriate for integration into LFA for sample-to-answer NAT at the point-of-care (POC), usually due to the complicated fabrication processes or incompatible chemicals used. To address this, we propose a novel strategy of integrating a simple fluidic control strategy into LFA. The strategy involves incorporating a piece of paper-based shunt and a polydimethylsiloxane (PDMS) barrier to the strip to achieve optimum fluidic delays for LFA signal enhancement, resulting in 10-fold signal enhancement over unmodified LFA. The phenomena of fluidic delay were also evaluated by mathematical simulation, through which we found the movement of fluid throughout the shunt and the tortuosity effects in the presence of PDMS barrier, which significantly affect the detection sensitivity. To demonstrate the potential of integrating this strategy into a LFA with sample-in-answer-out capability, we further applied this strategy into our prototype sample-to-answer LFA to sensitively detect the Hepatitis B virus (HBV) in clinical blood samples. The proposed strategy offers great potential for highly sensitive detection of various targets for wide application in the near future.
With advances in point-of-care testing (POCT), lateral flow assays (LFAs) have been explored for nucleic acid detection. However, biological samples generally contain complex compositions and low amounts of target nucleic acids, and currently require laborious off-chip nucleic acid extraction and amplification processes (e.g., tube-based extraction and polymerase chain reaction (PCR)) prior to detection. To the best of our knowledge, even though the integration of DNA extraction and amplification into a paper-based biosensor has been reported, a combination of LFA with the aforementioned steps for simple colorimetric readout has not yet been demonstrated. Here, we demonstrate for the first time an integrated paper-based biosensor incorporating nucleic acid extraction, amplification and visual detection or quantification using a smartphone. A handheld battery-powered heating device was specially developed for nucleic acid amplification in POC settings, which is coupled with this simple assay for rapid target detection. The biosensor can successfully detect Escherichia coli (as a model analyte) in spiked drinking water, milk, blood, and spinach with a detection limit of as low as 10-1000 CFU mL(-1), and Streptococcus pneumonia in clinical blood samples, highlighting its potential use in medical diagnostics, food safety analysis and environmental monitoring. As compared to the lengthy conventional assay, which requires more than 5 hours for the entire sample-to-answer process, it takes about 1 hour for our integrated biosensor. The integrated biosensor holds great potential for detection of various target analytes for wide applications in the near future.
Paper-based devices have been broadly used for the point-of-care detection of dengue viral nucleic acids due to their simplicity, cost-effectiveness, and readily observable colorimetric readout. However, their moderate sensitivity and functionality have limited their applications. Despite the above-mentioned advantages, paper substrates are lacking in their ability to control fluid flow, in contrast to the flow control enabled by polymer substrates (e.g., agarose) with readily tunable pore size and porosity. Herein, taking the benefits from both materials, the authors propose a strategy to create a hybrid substrate by incorporating agarose into the test strip to achieve flow control for optimal biomolecule interactions. As compared to the unmodified test strip, this strategy allows sensitive detection of targets with an approximately tenfold signal improvement. Additionally, the authors showcase the potential of functionality improvement by creating multiple test zones for semi-quantification of targets, suggesting that the number of visible test zones is directly proportional to the target concentration. The authors further demonstrate the potential of their proposed strategy for clinical assessment by applying it to their prototype sample-to-result test strip to sensitively and semi-quantitatively detect dengue viral RNA from the clinical blood samples. This proposed strategy holds significant promise for detecting various targets for diverse future applications.
17β-Estradiol-E2 (17β-E2) is a steroid hormone that plays a major role in the reproductive endocrine system and is involved in various processes, such as pregnancy, fertility, and menopause. In this study, the performance of an enzyme-linked immunosorbent assay (ELISA) for 17β-E2 quantification was enhanced by using a gold nanoparticle (GNP)-conjugated aptamer. An anti-17β-E2-aptamer-GNP antibody was immobilized on an amine-modified ELISA surface. Then, 17β-E2 was allowed to interact with and be sandwiched by antibodies. Aptamer-GNP conjugation was confirmed by colorimetric assays via the naked eye and UV-visible light spectroscopy. The detection limit based on a signal-to-noise ratio (S/N) of 3 was estimated to be 1.5 nM (400 pg/mL), and the linear range was 1.5-50 nM. Control experiments (without 17β-E2/with a complementary aptamer sequence/with a nonimmune antibody) confirmed the specific detection of 17β-E2. Moreover, 17β-E2 spiking of human serum did not interrupt the interaction between 17β-E2 and its antibody and aptamer. Thus, the developed ELISA can be used as an alternate assay for quantification of 17β-E2 and assessment of endocrine-related gynecological problems.
A dinuclear gold(I) pyrrolidinedithiocarbamato complex (1) with a bidentate carbene ligand has been constructed and shows potent in vitro cytotoxic activities towards cisplatin-resistant ovarian cancer cells A2780cis. Its rigid scaffold enables a zinc(II)-based metal-organic framework (Zn-MOF) to be used as a carrier in facilitating the uptake and release of 1 in solutions. Instead of using a conventional dialysis approach for the drug-release testing, in this study, a set of transwell assay-based experiments have been designed and employed to examine the cytotoxic and antimigratory activities of 1@Zn-MOF towards A2780cis.
Conventional cancer treatment techniques show several limitations including low or no specificity and consequently a low efficacy in discriminating between cancer cells and healthy cells. Recent nanotechnology developments have introduced smart and novel therapeutic nanomaterials that take advantage of various targeting approaches. The use of nanotechnology in medicine and, more specifically, drug delivery is set to spread even more rapidly than it has over the past two decades. Currently, many nanoparticles (NPs) are under investigation for drug delivery including those for cancer therapy. Targeted nanomaterials bind selectively to cancer cells and greatly affect them with only a minor effect on healthy cells. Gold nanoparticles (Au-NPs), specifically, have been identified as significant candidates for new cancer therapeutic modalities because of their biocompatibility, easy functionalization and fabrication, optical tunable characteristics, and chemophysical stability. In the last decade, there has been significant research on Au-NPs and their biomedical applications. Functionalized Au-NPs represent highly attractive and promising candidates for drug delivery, owing to their unique dimensions, tunable surface functionalities, and controllable drug release. Further, iron oxide NPs due to their "superparamagnetic" properties have been studied and have demonstrated successful employment in numerous applications. In targeted drug delivery systems, drug-loaded iron oxide NPs can accumulate at the tumor site with the aid of an external magnetic field. This can lead to incremental effectiveness in drug release to the tumor site and vanquish cancer cells without harming healthy cells. In order for the application of iron oxide NPs in the human body to be realized, they should be biodegradable and biocompatible to minimize toxicity. This review illustrates recent advances in the field drug and small molecule delivery such as fluorouracil, folic acid, doxorubicin, paclitaxel, and daunorubicin, specifically when using gold and iron oxide NPs as carriers of anticancer therapeutic agents.