Naked-Eye Detection of Mercury Ions from Morphological Transition of Silver Nanocubes: Tuning Sensitivity Using Co-Staining Agent.

A simple, low-cost and highly selective nanosensor was developed for naked-eye detection of mercury ions (Hg2+) based on Eosin/silver nanocubes (Eosin/AgNCbs). Silver nanocubes (AgNCbs) were synthesized by polyol assisted chemical method. HR-TEM result shows the formed AgNCbs have a mean diameter of 84±0.005 nM (diagonally measured) and edge length of 55±0.01 nM. XRD result confirms that the AgNCbs are single crystalline in nature with a phase structure of face centered cubic (FCC) of silver. On interaction of Hg2+, AgNCbs exhibits a color change from gray to black up to 16.67 µM of Hg2+ owed to the formation of solid like bimetallic complex of Ag/Hg amalgam. The selectivity of AgNCbs was evaluated with several other toxic metal ions including, Mg2+, Ba2+, Ca4+, Pb2+, Cd4+, Zn2+, Co2+, Cu2+, K+ and Ni2+ and found good selectivity towards Hg2+. The sensitivity of the AgNCbs sensor system was tuned by using Eosin as a co-staining agent. The Eosin/AgNCbs showed a limit of detection of 60±0.050 nM with the color change from orange to purple. The results suggests that the Eosin/AgNCbs nanosensor exhibits good selectivity, sensitivity, repeatability and rapid response, which could be explored for real-time detection of Hg2+ in environmental and biological samples.

Fabrication and Characterization of Multifunctional Curcumin Loaded Poly(methyl methacrylate) Fluorescent Nanofiber Membrane.

This work aims at the development of curcumin loaded poly(methyl methacrylate) (CC-PMMA) fluorescent nanofiber membrane and the evaluation of its multifunctional characteristics. The nanofibers were created by electrospinning method. The conditions of the spinning were optimized to obtain beadless and smooth nanofibers. The physico-chemical characteristics of the nanofibers were studied by various techniques including, polarizing light microscope, FT-IR, inverted epi fluorescence microscope and HR-TEM. The HR-TEM results confirm the formation of nanofibers with the diameter in the range of 90-200 nm. The average width of PMMA and CC-PMMA nanofibers are ˜90±0.02 nm and ˜110±0.01 nm, respectively. The CC-PMMA nanofibers exhibited the fluorescence shift with an emission around 520 nm. The multifunctional characteristic of CC-PMMA nanofiber was evaluated for sensor and antibacterial applications. The CC-PMMA nanofiber membrane showed a visible color variation from yellow to red on interaction with ammonia. This colorimetric response to ammonia is highly selective and there was no any interference from other related organic vapors. In addition, it showed good antibacterial activities for Gram-positive and Gram-negative bacteria (zone of inhibition of 27 mm for S. aureus). This is the initial research report in the combination of curcumin and PMMA nanofiber. The multifunctionality of the CC-PMMA nanofibers could be exploited for various applications including sensors, antibacterial coatings, air filtration and drug delivery.

Nanoformulations for Targeted Drug Delivery to Prostate Cancer: An Overview.

Cancer is the second leading causes of death worldwide and it is one of the fatal diseases that kill millions of people every year. It is characterized by uncontrolled proliferation of cells and loss of apoptosis that generates an abnormal mass of cells or tumors. Prostate cancer (PCa) is one of the most common cancers in men and the risk is higher over the age of 55-65. Currently, PCa is the second most common cancer, which causes death in men has a high prevalence with relatively lower cancer mortality risk compared to lung and colon cancer. Management of cancer remains an ongoing challenge in oncology as it is a pathophysiological and heterogeneous disease. The current treatment options such as surgery, chemotherapy, radiation therapy available for cancer therapies are inadequate due to the heterogeneity characteristics of cancer and spur demand for improved technologies. Nanotechnology is an emerging and potential platform that uses nanoparticles for the disease diagnosis to targeted drug delivery system (DDS). One of the most important active research fields of nanotechnology is nanomedicine, which provides solutions to the difficulties of conventional chemotherapy. Nanoformulation based drug delivery enhances the properties to improve the pharmacokinetics profile, bioavailability and these drug carriers increases the therapeutic efficiency compared to the regular chemotherapeutic drugs. Moreover, nanoformulated drugs help to overcome the lack of selectivity and adverse side effects of conventional chemotherapy. This review provides an overview of PCa drug delivery systems. A special emphasis is given to research work around the world in the development of nanoformulations for targeted drug delivery to PCa.

An Overview on Applications of Gold Nanoparticle for Early Diagnosis and Targeted Drug Delivery to Prostate Cancer.

BACKGROUND: Carcinoma of the prostate gland (PCa) is one of the most commonly diagnosed cancer diseases among men around the world. PCa has become the major considerable health and epidemic problem which causes death in men with a high prevalence and relatively lower mortality risk. The inability of conventional diagnosis tools to detect cancer at an early and potentially curable stage further hinders effective treatment options and spur demand for improved technologies. Nanoparticles are emerging as a versatile tool for disease diagnosis to therapy. Gold nanoparticles (AuNPs) have a huge potential in targeted drug delivery and detection of cancerous cells. Diverse predominant distinctive properties of gold nanomaterials and their effective functionalization make them a suitable material for early diagnosis and effective treatment of cancer. OBJECTIVE: To summarize the recent research and patents on the development of multifunctional AuNPs based nanoformulations for early diagnosis and targeted drug delivery to prostate cancer. Further, discussion on the salient features of gold nanostructures and its evaluation of extremely attractive vectors in prostate cancer diagnosis and treatments. CONCLUSION: This review summarizes the use of AuNPs based nanoformulations in cancer diagnostics and therapy, which has been recognized as an important platform as smart materials for clinical application. The ability to tune the size, shape and the physical properties of AuNPs along with their low toxicity, biocompatibility and large surface chemistry makes them as a promising candidate for clinical use.

Surface plasmon resonance biosensor for dopamine using D3 dopamine receptor as a biorecognition molecule.

In modern biomedical technology, development of high performance sensing methods for dopamine (DA) is a critical issue because of its vital role in human metabolism. We report here, a new kind of bioaffinity sensor for DA based on surface plasmon resonance (SPR) using a D(3) dopamine receptor (DA-RC) as a recognition element. A conjugate of DA was synthesized using bovine serum albumin (BSA) protein and was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The biosensor surface was constructed by the immobilization of the DA-BSA conjugate onto an SPR gold surface by physical adsorption. Atomic force microscopy (AFM) investigations revealed that the DA-BSA conjugate was homogeneously distributed over the sensor surface. Specific interaction of the DA-RC with the immobilized DA-BSA conjugate was studied by SPR. Based on the principle of indirect competitive inhibition, the biosensor could detect DA in a linear dynamic range from 85 pg/ml (ppt) to 700 ng/ml (ppb). The biosensor was highly specific for DA and showed no significant interference from potent interferences such as ascorbic acid (AA), uric acid (UA) and other DA analogues viz., 3,4 dihydroxyphenyl acetic acid (DOPAC) and 3-(3,4 dihydroxyphenyl)-alanine (DOPA). The sensor surface displayed a high level of stability during repeated regeneration and affinity reaction cycles. Since this biosensor is simple, effective and is based on utilization of natural receptor, our study presents an encouraging scope for development of portable detection systems for in-vitro and in-vivo measurement of DA in clinical and medical diagnostics.

Fabrication of a novel immunosensor using functionalized self-assembled monolayer for trace level detection of TNT by surface plasmon resonance.

We have developed a new immunosensor based on self-assembly chemistry for highly sensitive and label-free detection of 2,4,6-trinitrotoluene (TNT) using surface plasmon resonance (SPR). A monolayer of amine terminated poly(ethylene glycol) hydrazinehydrochloride (PEG-NH(2)) thiolate was constructed on an activated gold surface and immobilized with trinitrophenyl-beta-alanine (TNPh-beta-alanine) by amide coupling method. The binding interaction of a monoclonal anti-TNT Ab (M-TNT Ab) with TNPh-beta-alanine immobilized thiolate monolayer surface was monitored and evaluated for detection of TNT based on the principle of indirect competitive immunoreaction. Here, the competition between the self-assembled TNT derivative and the TNT in solution for binding with antibody yields in the response signal that is inversely proportional to the concentration of TNT in the linear detection range. With the present immunoassay format, TNT could be detected in the concentration range from 0.008ng/ml (8ppt) to 30ng/ml (30ppb). The response time for an immunoreaction was 2min and one immunocycle could be done with in 4min including surface regeneration. Bound antibodies could be easily eluted from the self-assembled immunosurface at high recoveries (more than 100 cycles) using pepsin solution without any damage to the TNT derivatives immobilized on the surface. The compact self-assembled monolayer was highly stable and prevented the non-specific adsorption of proteins on the surface favoring error free measurement.

Recent progress and challenges in nanotechnology for biomedical applications: an insight into the analysis of neurotransmitters.

Nanotechnology offers exciting opportunities and unprecedented compatibilities in manipulating chemical and biological materials at the atomic or molecular scale for the development of novel functional materials with enhanced capabilities. It plays a central role in the recent technological advances in biomedical technology, especially in the areas of disease diagnosis, drug design and drug delivery. In this review, we present the recent trend and challenges in the development of nanomaterials for biomedical applications with a special emphasis on the analysis of neurotransmitters. Neurotransmitters are the chemical messengers which transform information and signals all over the body. They play prime role in functioning of the central nervous system (CNS) and governs most of the metabolic functions including movement, pleasure, pain, mood, emotion, thinking, digestion, sleep, addiction, fear, anxiety and depression. Thus, development of high-performance and user-friendly analytical methods for ultra-sensitive detection of neurotransmitters remain a major challenge in modern biomedical analysis. Nanostructured materials are emerging as a powerful mean for diagnosis of CNS disorders because of their unique optical, size and surface characteristics. This review provides a brief outline on the basic concepts and recent advancements of nanotechnology for biomedical applications, especially in the analysis of neurotransmitters. A brief introduction to the nanomaterials, bionanotechnology and neurotransmitters is also included along with discussions on most of the patents published in these areas.

Evaluation of the molecular recognition of monoclonal and polyclonal antibodies for sensitive detection of 2,4,6-trinitrotoluene (TNT) by indirect competitive surface plasmon resonance immunoassay.

Detection of TNT is an important environmental and security concern all over the world. We herein report the performance and comparison of four immunoassays for rapid and label-free detection of 2,4,6-trinitrotoluene (TNT) based on surface plasmon resonance (SPR). The immunosensor surface was constructed by immobilization of a home-made 2,4,6-trinitrophenyl-keyhole limpet hemocyanin (TNPh-KLH) conjugate onto an SPR gold surface by simple physical adsorption within 10 min. The immunoreaction of the TNPh-KLH conjugate with four different antibodies, namely, monoclonal anti-TNT antibody (M-TNT Ab), monoclonal anti-trinitrophenol antibody (M-TNP Ab), polyclonal anti-trinitrophenyl antibody (P-TNPh Ab), and polyclonal anti-TNP antibody (P-TNP Ab), was studied by SPR. The principle of indirect competitive immunoreaction was employed for quantification of TNT. Among the four antibodies, the P-TNPh Ab prepared by our group showed highest sensitivity with a detection limit of 0.002 ng/mL (2 ppt) TNT. The lowest detection limits observed with other commercial antibodies were 0.008 ng/mL (8 ppt), 0.25 ng/mL (250 ppt), and 40 ng/mL (ppb) for M-TNT Ab, P-TNP Ab, and M-TNP Ab, respectively, in the similar assay format. The concentration of the conjugate and the antibodies were optimized for use in the immunoassay. The response time for an immunoreaction was 36 s and a single immunocycle could be done within 2 min, including the sensor surface regeneration using pepsin solution. In addition to the quantification of TNT, all immunoassays were evaluated for robustness and cross-reactivity towards several TNT analogs.

Surface plasmon resonance immunosensor for highly sensitive detection of 2,4,6-trinitrotoluene.

We have examined the sensing characteristics of a surface plasmon resonance (SPR) immunoassay for the detection of 2,4,6-trinitrotoluene (TNT) using an immunoreaction between 2,4,6-trinitrophenol-ovalbumin (TNP-OVA) conjugate and anti-2,4,6-trinitrophenol antibody (anti-TNP antibody). TNP-OVA conjugate was attached to a SPR-gold sensing surface by means of physical immobilization, which undergoes binding interaction with anti-TNP antibody. Both the immobilization and binding processes were studied from a change in the SPR-resonance angle. The quantification of TNT is based on the principle of indirect competitive immunoassay, in which the immunoreaction between the TNP-OVA conjugate and anti-TNP antibody was inhibited in the presence of free TNT in solution. The decrease in the resonance angle shift is proportional to an increase in concentration of TNT used for incubation. The immunoassay exhibited excellent sensitivity for the detection of TNT in the concentration range from 0.09 to 1000 ng/ml with good stability and reproducibility. The immunosensor developed could detect TNT as low as 0.09 ng/ml, within a response time of approximately 22 min. The sensor surface was regenerated by a brief flow of pepsin solution, which disrupts the antigen-antibody complex without destroying the conjugate biofilm. Cross-reactivity of the SPR sensor to some structurally related nitroaromatic derivative and the detection of TNT in the presence of these nitroaromatic compounds were investigated. The cross-reactivity of the SPR sensor to 2,4-dinitrotoluene (2,4-DNT), 1,3-dinitrobenzene (1,3-DNB), 2-amino-4,6-dinitrotoluene (2A-4,6-DNT) and 4-amino-2,6-dinitrotoluene (4A-2,6-DNT) were very low (< or =1.1%). The analytical characteristics of the proposed immunosensor are highly promising for the development of new field-portable sensors for on-site detection of landmines.