Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

2D Nanomaterials and Their Drug Conjugates for Phototherapy and Magnetic Hyperthermia Therapy of Cancer and Infections

Photothermal therapy (PTT) and magnetic hyperthermia therapy (MHT) using 2D nanomaterials (2DnMat) have recently emerged as promising alternative treatments for cancer and bacterial infections, both important global health challenges. The present review intends to provide not only a comprehensive overview, but also an integrative approach of the state-of-the-art knowledge on 2DnMat for PTT and MHT of cancer and infections. High surface area, high extinction coefficient in near-infra-red (NIR) region, responsiveness to external stimuli like magnetic fields, and the endless possibilities of surface functionalization, make 2DnMat ideal platforms for PTT and MHT. Most of these materials are biocompatible with mammalian cells, presenting some cytotoxicity against bacteria. However, each material must be comprehensively characterized physiochemically and biologically, since small variations can have significant biological impact. Highly efficient and selective in vitro and in vivo PTTs for the treatment of cancer and infections are reported, using a wide range of 2DnMat concentrations and incubation times. MHT is described to be more effective against bacterial infections than against cancer therapy. Despite the promising results attained, some challenges remain, such as improving 2DnMat conjugation with drugs, understanding their in vivo biodegradation, and refining the evaluation criteria to measure PTT or MHT effects.

SPIONs Conjugate Supported Anticancer Drug Doxorubicin's Delivery: Current Status, Challenges, and Prospects

Considerable efforts have been directed towards development of nano-structured carriers to overcome the limitations of anticancer drug, doxorubicin's, delivery to various cancer sites. The drug's severe toxicity to cardio and hepatic systems, low therapeutic outcomes, inappropriate dose-demands, metastatic and general resistance, together with non-selectivity of the drug have led to the development of superparamagnetic iron oxide nanoparticles (SPIONs)-based drug delivery modules. Nano-scale polymeric co-encapsulation of the drug, doxorubicin, with SPIONs, the SPIONs surface end-groups' cappings with small molecular entities, as well as structural modifications of the SPIONs' surface-located functional end-groups, to attach the doxorubicin, have been achieved through chemical bonding by conjugation and cross-linking of natural and synthetic polymers, attachments of SPIONs made directly to the non-polymeric entities, and attachments made through mediation of molecular-spacer as well as non-spacer mediated attachments of several types of chemical entities, together with the physico-chemical bondings of the moieties, e.g., peptides, proteins, antibodies, antigens, aptamers, glycoproteins, and enzymes, etc. to the SPIONs which are capable of targeting multiple kinds of cancerous sites, have provided stable and functional SPIONs-based nano-carriers suitable for the systemic, and in vitro deliveries, together with being suitable for other biomedical/biotechnical applications. Together with the SPIONs inherent properties, and ability to respond to magnetic resonance, fluorescence-directed, dual-module, and molecular-level tumor imaging; as well as multi-modular cancer cell targeting; magnetic-field-inducible drug-elution capacity, and the SPIONs' magnetometry-led feasibility to reach cancer action sites have made sensing, imaging, and drug and other payloads deliveries to cancerous sites for cancer treatment a viable option. Innovations in the preparation of SPIONs-based delivery modules, as biocompatible carriers; development of delivery route modalities; approaches to enhancing their drug delivery-cum-bioavailability have explicitly established the SPIONs' versatility for oncological theranostics and imaging. The current review outlines the development of various SPIONs-based nano-carriers for targeted doxorubicin delivery to different cancer sites through multiple methods, modalities, and materials, wherein high-potential nano-structured platforms have been conceptualized, developed, and tested for, both, in vivo and in vitro conditions. The current state of the knowledge in this arena have provided definite dose-control, site-specificity, stability, transport feasibility, and effective onsite drug de-loading, however, with certain limitations, and these shortcomings have opened the field for further advancements by identifying the bottlenecks, suggestive and plausible remediation, as well as more clear directions for future development.

Vinblastine Loaded On Graphene Quantum Dots And Its Anticancer Applications

AIMS

The aim of our work is to load Vinblastine drug loaded on graphene quantum dots to improve its cytotoxicity on cancer cells and reduce it on normal cell in the composites. Moreover, GQDs-Vin composite significantly inhibited the tumor growth in animals.

METHODS

GQDs-Vin composites were prepared by homogenization of GQDs and Vin solutions. The loading of Vin on GQDs in the composites were characterized by FTIR, PL, UV-vis spectra, and TEM. The cytotoxicity of GQDs, Vin, and GQDs-Vin composites was investigated on the Hela, HGC-27, A549, MCF-7, CCF-STTG1 cells and Vero by in vitro and in vivo methods. The difference in cellular structure and organelles in mice's livers in comparison between control group and GQDs-Vin (1:5) groups was characterized by TEM.

RESULTS

The diameter of the nanoparticles of GQDs-Vin composites in weight ratios 1:1, 1:3 and 1:5 w/w of 50-70 nm, 100-150 nm and ∼500nm, respectively, is larger than that of GQDs of 10-50nm. The in vitro results showed that GQDs not only improved the cytotoxicity of Vin to cancer cells, but also decreased its cytotoxicity towards normal cells in the composites. The GQDs-Vin (1:5) composite exhibited a stronger tumor inhibition effect than Vin alone. The morphology of mice's livers showed the absence GQDs-Vin nanoparticles in the mice's livers suggests the lack of storage and the leakage from the liver without any toxicity.

CONCLUSIONS

Results of the improved cytotoxicity of GQDs-Vin composite on cancer cells, its reduced cytotoxicity on normal cell and the significant inhibition on tumor growth of GQDs-Vin composite compared with Vin and GQDs alone may indicate a synergistic effect of Vin and GQDs in their composites for anticancer application.

Deeply Infiltrating iRGD-Graphene Oxide for the Intensive Treatment of Metastatic Tumors through PTT-Mediated Chemosensitization and Strengthened Integrin Targeting-Based Antimigration

A limited infiltration and the subsequent low effective drug concentration result in poor chemotherapeutic outcomes against tumors, and even further promote tumor resistance and metastatic. Herein, iRGD-modified graphene oxide (GO) nanosheets (IPHG) are developed for the intensive treatment of metastatic tumors using focus-specific penetrated delivery together with photothermal therapy-mediated chemosensitization and photothermal therapy-strengthened integrin targeting-based antimigration. In vitro and in vivo data verified the mechanism of the tumor-selective infiltration of IPHG is based on a rigid 2D structure-associated advantage regarding hemodynamics and endothelial contact, followed by iRGD-endowed transendothelial and intratumoral transport. Once IPHG-DOX-penetrated 4T1 tumors are exposed to near-infrared irradiation, hyperthermia stress and photothermal therapy-elevated effective drug concentrations result in chemosensitization and prominent tumor suppression. Meanwhile, the specific binding of iRGD to integrins and photothermal therapy leads to the synergistic perturbation of cytoskeleton remodeling and subsequent impairment of cell motility and metastasis. The tailored design of IPHG validates a promising paradigm for drug delivery to combat tumor resistance and metastasis resulting from poor target access for single chemotherapy.

A graphene-sandwiched DNA nano-system: regulation of intercalated doxorubicin for cellular localization

Control of the sub-cellular localization of nanoparticles (NPs) with enhanced drug-loading capacity, employing graphene oxide (GO), iron oxide (Fe3O4) NPs and sandwiched deoxyribonucleic acid (DNA) bearing intercalated anticancer drug doxorubicin (DOX) has been investigated in this work. The nanosystems G-DNA-DOX-Fe3O4 and Fe3O4-DNA-DOX differentially influence serum protein binding and deliver DOX to lysosomal compartments of cervical cancer (HeLa) cells with enhanced retention. Stern-Volmer plots describing BSA adsorption on the nanosystems demonstrated the quenching constants, K sv for G-DNA-DOX-Fe3O4 and Fe3O4-DNA-DOX (0.025 mL μg-1 and 0.0103 mL μg-1 respectively). Nuclear DOX intensity, measured at 24 h, was ∼2.0 fold higher for Fe3O4-DNA-DOX in HeLa cells. Parallelly, the cytosol displayed ∼2.2 fold higher DOX intensity for Fe3O4-DNA-DOX compared to G-DNA-DOX-Fe3O4. Fe3O4-DNA-DOX was more efficacious in the cytotoxic effect than G-DNA-DOX-Fe3O4 (viability of treated cells: 33% and 49% respectively). The DNA:nanosystems demonstrated superior cytotoxicity compared to mole-equivalent free DOX administration. The results implicate DNA:DOX NPs in influencing the cellular uptake mechanism and were critically subject to cellular localization. Furthermore, cell morphology analysis evidenced maximum deformation attributed to free-DOX with 34% increased cell roundness, 63% decreased cell area and ∼1.9 times increased nuclear-to-cytoplasmic (N/C) ratio after 24 h. In the case of Fe3O4-DNA-DOX, the N/C ratio increased 1.2 times and a maximum ∼37% decrease in NSA was noted suggesting involvement of non-canonical cytotoxic pathways. In conclusion, the study makes a case for designing nanosystems with controlled and regulated sub-cellular localization to potentially exploit secondary cytotoxic pathways, in addition to optimized drug-loading for enhanced anticancer efficacy and reduced adverse effects.

99mTc-doxorubicin-loaded gallic acid-gold nanoparticles (99mTc-DOX-loaded GA-Au NPs) as a multifunctional theranostic agent

The development of cancer theranostic nanomedicines is recommended to concurrently achieve and evaluate the therapeutic benefit and progress. The current work aims to develop gallic acid-gold nanoparticles (GA-Au NPs) as a theranostic probe for ^99mTc-Doxorubicin (^99mTc-DOX) based on the spatiotemporal release pattern induced intra-tumoral (IT) delivery. DOX-loaded GA-Au NPs were developed and identified via UV-Vis spectroscopy. The system was characterized for drug loading efficiency%, particle size, zeta potential, topography, in vitro DOX release and anti-proliferative activity against the MCF-7 cell-line. The factors influencing radiolabeling efficiency of DOX with ^99mTc (DOX concentration, stannous chloride concentration, reaction time and pH) were optimized. The in vitro stability in mice serum and in vivo distribution studies in mice of ^99mTc-DOX-loaded GA-Au NPs were investigated following IV and IT administration. Dox-loaded GA-Au NPs had a loading efficiency of 91%, a small particle size (≈50 nm), a promising zeta potential (-20 mV) and a sustained drug release profile at pH 5.3. GA-Au NPs exhibited increased anti-proliferative activity, with approximately a four-fold lower IC₅₀ value (0.15 μg/ml) than free DOX. The optimized radiolabeling efficiency of ^99mTc-DOX was ≈93%. It showed good physiological stability in mice serum for at least 8 h. The IT delivery of ^99mTc-DOX-loaded GA-Au NPs in tumor-induced mice showed dramatic tumor accumulation. A maximum magnitude of 86.73%ID/g was achieved, at 15 min post-injection, with a target/non-target ratio of ≈56. ^99mTc-DOX-loaded GA-Au NPs could be used for the selective IT delivery of a chemotherapeutic agent and an imaging agent to a target organ.

Polymerized graphene oxide/MnCe0.5Fe1.5O4 nanoferrofluid as a T2- and T2*-weighted contrast agent for magnetic resonance imaging

In this study synthesis of graphene oxide-poly citric acid/MnCe_0.5Fe_1.5O₄ nanoferrofluid with a simple method and its ability for enhancing the contrast of magnetic resonance images was reported. The co-precipitation method has been used for the production of MnCe_0.5Fe_1.5O₄ nanoparticles with a size distribution of 25-40 nm, which has shown a very good superparamagnetic property with saturation magnetization (M_s) 53.6 emu g^-1. Graphene oxide (GO) was prepared by a modified Hummers method and polymerized with citric acid to produce GO-PCA. The nanoparticles were loaded on the GO-PCA surface to produce nanoferrofluid that showed excellent colloidal stability, extra dispersibility, and good magnetic properties with M_s equal to 47.8 emu g^-1. This nanoferrofluid has an increased effect on the contrast of T₂ and T₂*-weighted images, with the values 109.15 and 180.23 mM^-1 s^-1 for r₂ and r₂*, respectively at 3.0 T. The cellular uptake evaluation revealed adequate uptake for HeLa cell lines.

Graphene aerogel nanoparticles for in-situ loading/pH sensitive releasing anticancer drugs

Free polymer graphene aerogel nanoparticles (GA NPs) were synthesized by using reduction/aggregation of graphene oxide (GO) sheets in the presence of vitamin C (as a biocompatible reductant agent) at a low temperature (40 °C), followed by an effective sonication. Synthesis of GA NPs in doxorubicin hydrochloride (DOX)-containing solution results in the simultaneous synthesis and drug loading with higher performance (than that of the separately synthesized and loaded samples). To investigate the mechanism of loading and the capability of GA NPs in the loading of other drug structures, two groups of ionized (DOX, Amikacin sulfate and, d-glucosamine hydrochloride) and non-ionized (Paclitaxel (PTX)) drugs were examined. Furthermore, the relationship between the bipolar level of DOX solution (contributing to H-bonding of DOX and GO) and the amount of DOX loading was investigated. The DOX showed higher loading (>3 times) than PTX, as anticancer drugs. Since both DOX and PTX possess aromatic structures, the higher loading of DOX was assigned to its positive partial charge and ionized nature. Accordingly, other drugs (having positive partial charge and ionized nature, but no aromatic structure) such as Amikacin sulfate and d-glucosamine hydrochloride presented higher loading than PTX. These results indicated that although the π-π interactions induced by aromatic structures are important in drug loading, the electrostatic interaction of ionized drugs with GO (especially through H-bonding) is the dominant mechanism. DOX-loaded GANPs showed high pH-sensitive release (equivalent to the carrier weight) after 5 days, which can indicate benefits in tumor cell acidic microenvironments in-vivo.

Multifunctional graphene oxide/iron oxide nanoparticles for magnetic targeted drug delivery dual magnetic resonance/fluorescence imaging and cancer sensing

Graphene Oxide (GO) has recently attracted substantial attention in biomedical field as an effective platform for biological sensing, tissue scaffolds and in vitro fluorescence imaging. However, the targeting modality and the capability of its in vivo detection have not been explored. To enhance the functionality of GO, we combine it with superparamagnetic iron oxide nanoparticles (Fe3O4 NPs) serving as a biocompatible magnetic drug delivery addends and magnetic resonance contrast agent for MRI. Synthesized GO-Fe3O4 conjugates have an average size of 260 nm and show low cytotoxicity comparable to that of GO. Fe3O4 nanoparticles provide superparamagnetic properties for magnetic targeted drug delivery allowing simple manipulation by the magnetic field and magnetic resonance imaging with high r2/r1 relaxivity ratios of ~10.7. GO-Fe3O4 retains pH-sensing capabilities of GO used in this work to detect cancer versus healthy environments in vitro and exhibits fluorescence in the visible for bioimaging. As a drug delivery platform GO-Fe3O4 shows successful fluorescence-tracked transport of hydrophobic doxorubicin non-covalently conjugated to GO with substantial loading and 2.5-fold improved efficacy. As a result, we propose GO-Fe3O4 nanoparticles as a novel multifunctional magnetic targeted platform for high efficacy drug delivery traced in vitro by GO fluorescence and in vivo via MRI capable of optical cancer detection.

Carbon Nanotubes as A High-Performance Platform for Target Delivery of Anticancer Quinones

BACKGROUND

In spite of considerable efforts of researchers the cancer deseases remain to be incurable and a percentage of cancer deseases in the structure of mortality increases every year. At that, high systemic toxicity of antitumor drugs hampers their effective use. Because of this fact, the development of nanosystems for targeted delivery of antitumor drugs is one of the leading problem in nanomedicine and nanopharmacy.

OBJECTIVE

To critically examine the modern strategies for carbon nanotubes (CNTs)-based delivery of anticancer quinones and to summarize the mechanisms which can provide high effectiveness and multifunctionality of the CNT-based quinone delivery platform.

RESULTS

Quinones, including anthracycline antibiotics - doxorubicin and daunorubicin, are among the most prospective group of natural and syntetic compounds which exhibit high antitumor activity against different type of tumors. In this review, we focus on the possibilities of using CNTs for targeted delivery of antitumor compounds with quinoid moiety which is ordinarily characterized by high specific interaction with DNA molecules. Quinones can be non-covalently adsorbed on CNT surface due to their aromatic structure and π-conjugated system of double bonds. The characteristic features of doxorubicine-CNT complex are high loading efficiency, pH-dependent release in acidic tumor microenviroment, enough stability in biological fluid. Different types of CNT functionalization, targeting strategies and designs for multifunctional CNT-based doxorubicine delivery platform are disscussed.

CONCLUSION

Nanosystems based on functionalized CNTs are very promising platform for quinone delivery resulting in significant enhancement of cancer treatment efficiency. Functionalization of CNTs with the polymeric shell, especially DNA-based shells, can provide the greatest affinity and mimicry with biological structures.

Systematic Investigation of Two-Dimensional DNA Nanoassemblies for Construction of a Nonspecific Sensor Array

We have performed a systematic study to analyze the effect of ssDNA length, nucleobase composition, and the type of two-dimensional nanoparticles (2D-nps) on the desorption response of 36 two-dimensional nanoassemblies (2D-NAs) against several proteins. The studies were performed using fluorescently labeled polyA, polyC, and polyT with 23, 18, 12, and 7 nucleotide-long sequences. The results suggest that the ssDNAs with polyC and longer sequences are more resistant to desorption, compared to their counterparts. In addition, 2D-NAs assembled using WS₂ were least susceptible to desorption by the proteins tested, whereas nGO 2D-NAs were the most susceptible nanoassemblies. Later, the results of these systematic studies were used to construct a sensor array for discrimination of seven model proteins (BSA, lipase, alkaline phosphatase, acid phosphatase, protease, β-galactosidase, and Cytochrome c). Neither the ssDNAs nor the 2D-nps have any specific interaction with the proteins tested. Only the displacement of the ssDNAs from the 2D-np surface was measured upon the disruption of the existing forces within 2D-NAs. A customized sensor array with five 2D-NAs was developed as a result of a careful screening/filtering process. The sensor array was tested against 200 nM of protein targets, and each protein was discriminated successfully. The results suggest that the systematic studies performed using various ssDNAs and 2D-nps enabled the construction of a sensor array without a bind-and-release sensing mechanism. The studies also demonstrate the significance of systematic investigations in the construction of two-dimensional DNA nanoassemblies for functional studies.

Gold nanocatalysts supported on carbon for electrocatalytic oxidation of organic molecules including guanines in DNA

Gold (Au) is chemically stable and resistant to oxidation. Although bulk Au is catalytically inert, nanostructured Au exhibits unique size-dependent catalytic activity. When Au nanocatalysts are supported on conductive carbon (denoted as Au@C), Au@C becomes promising for a wide range of electrochemical reactions such as electrooxidation of alcohols and electroreduction of carbon dioxide. In this mini-review, we summarize Au@C nanocatalysts with specific attention on the most recent achievements including the findings in our own laboratories, and show that Au nanoclusters (AuNCs, <2 nm) on nitrided carbon are excellent electrocatalysts for the oxidation of organic molecules including guanines in DNA. The state-of-the-art synthesis and characterization of these nanomaterials are also documented. Synergistic interactions among Au-containing multicomponents on carbon supports and their applications in electrocatalysis are discussed as well. Finally, challenges and future outlook for these emerging and promising nanomaterials are envisaged.

A bimodal theranostic nanodelivery system based on [graphene oxide-chlorogenic acid-gadolinium/gold] nanoparticles

We have synthesized a bimodal theranostic nanodelivery system (BIT) that is based on graphene oxide (GO) and composed of a natural chemotherapeutic agent, chlorogenic acid (CA) used as the anticancer agent, while gadolinium (Gd) and gold nanoparticles (AuNPs) were used as contrast agents for magnetic resonance imaging (MRI) modality. The CA and Gd guest agents were simultaneously loaded on the GO nanolayers using chemical interactions, such as hydrogen bonding and π-π non-covalent interactions to form GOGCA nanocomposite. Subsequently, the AuNPs were doped on the surface of the GOGCA by means of electrostatic interactions, which resulted in the BIT. The physico-chemical studies of the BIT affirmed its successful development. The X-ray diffractograms (XRD) collected of the various stages of BIT synthesis showed the successive development of the hybrid system, while 90% of the chlorogenic acid was released in phosphate buffer solution (PBS) at pH 4.8. This was further reaffirmed by the in vitro evaluations, which showed stunted HepG2 cancer cells growth against the above 90% cell growth in the control cells. A reverse case was recorded for the 3T3 normal cells. Further, the acquired T1-weighted image of the BIT doped samples obtained from the MRI indicated contrast enhancement in comparison with the plain Gd and water references. The abovementioned results portray our BIT as a promising future chemotherapeutic for anticancer treatment with diagnostic modalities.

Sonochemically synthesized blue fluorescent functionalized graphene oxide as a drug delivery system

Ultrasound assisted the copper-catalyzed cross-coupling reaction to synthesis 1-(10-bromoanthracene-9-yl)-1H-imidazole-4,5-dicarboxylic acid (A-Im). The obtained product was employed to modify graphene oxide (GO) surface to produce GO-A-Im. The resulted hybrid was characterized with Scanning Electron Microscope (SEM/EDS); X-ray Diffraction spectroscopy (XRD); X-ray photoelectron spectroscopy (XPS); Fluorescence spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), and UV-Vis absorption spectroscopy. The synthesized (A-Im) moiety that was used for functionalization of GO, display a cyan emission around (496 nm), however, the GO hybrid exhibited blue photoluminescence around (403 nm). It has been proposed that the chemical attachment of the A-Im moiety onto GO surface leads to a distortion in the bandgap of the GO and the blue shift of luminescence [93 nm] was observed. Indeed the cytotoxicity properties of the synthesized hybrid were measured. The IC₅₀ value for the hybrid was 23 µg/ml. The model drug (DOX) was loaded up to 91% on the carrier, and the release profile indicated a pH-dependent discharge with more release in acidic pH. The GO-A-Im/DOX was injected to the 4T1 tumor (murine breast cancer) bearing BALB/c mice and after 10 days the tumor was disappeared.

Graphene Oxide as a Nanocarrier for a Theranostics Delivery System of Protocatechuic Acid and Gadolinium/Gold Nanoparticles

We have synthesized a graphene oxide (GO)-based theranostic nanodelivery system (GOTS) for magnetic resonance imaging (MRI) using naturally occurring protocatechuic acid (PA) as an anticancer agent and gadolinium (III) nitrate hexahydrate (Gd) as the starting material for a contrast agent,. Gold nanoparticles (AuNPs) were subsequently used as second diagnostic agent. The GO nanosheets were first prepared from graphite via the improved Hummer's protocol. The conjugation of the GO and the PA was done via hydrogen bonding and π-π stacking interactions, followed by surface adsorption of the AuNPs through electrostatic interactions. GAGPA is the name given to the nanocomposite obtained from Gd and PA conjugation. However, after coating with AuNPs, the name was modified to GAGPAu. The physicochemical properties of the GAGPA and GAGPAu nanohybrids were studied using various characterization techniques. The results from the analyses confirmed the formation of the GOTS. The powder X-ray diffraction (PXRD) results showed the diffractive patterns for pure GO nanolayers, which changed after subsequent conjugation of the Gd and PA. The AuNPs patterns were also recorded after surface adsorption. Cytotoxicity and magnetic resonance imaging (MRI) contrast tests were also carried out on the developed GOTS. The GAGPAu was significantly cytotoxic to the human liver hepatocellular carcinoma cell line (HepG2) but nontoxic to the standard fibroblast cell line (3T3). The GAGPAu also appeared to possess higher T1 contrast compared to the pure Gd and water reference. The GOTS has good prospects of serving as future theranostic platform for cancer chemotherapy and diagnosis.

Switching off the interactions between graphene oxide and doxorubicin using vitamin C: combining simplicity and efficiency in drug delivery

Delivery of doxorubicin using graphene oxide is remarkably improved by adding a little amount of vitamin C.

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C-S cross-coupling reaction

The present work demonstrates the C–S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C–S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the agglomeration-free Ni NPs, the catalytic process is found to occur involving Ni(II) species and the recovered catalyst containing both Ni(0)/Ni(II) species is equally efficient in recycle runs. A correlation of loading of Ni species, size of NPs and the intermediate Ni-related heterostructures formed during the catalytic process has been established for the first time, and found to be best in the C–S cross-coupling reaction for Ni(0) and Ni(II) NPs of the average sizes 11–12 nm and 4 nm, respectively.

Universal sensor array for highly selective system identification using two-dimensional nanoparticles

A typical lock-and-key sensing strategy, relying only on the most dominant interactions between the probe and target, could be too limiting. In reality, the information received upon sensing is much richer. Non-specific events due to various intermolecular forces contribute to the overall received information with different degrees, and when analyzed, could provide a much more powerful detection opportunity. Here, we have assembled a highly selective universal sensor array using water-soluble two-dimensional nanoparticles (nGO, MoS2 and WS2) and fluorescent DNA molecules. The array is composed of 12 fluorescently silent non-specific nanoreceptors (2D-nps) and used for the identification of three radically different systems; five proteins, three types of live breast cancer cells and a structure-switching event of a macromolecule. The data matrices for each system were processed using Partial Least Squares (PLS) discriminant analysis. In all of the systems, the sensor array was able to identify each object or event as separate clusters with 95% confidence and without any overlap. Out of 15 unknown entities with unknown protein concentrations tested, 14 of them were predicted successfully with correct concentration. 8 breast cancer cell samples out of 9 unknown entities from three cell types were predicted correctly. During the assembly of each nanoprobe, the intrinsic non-covalent interactions between unmodified 2D nanoparticles and ssDNAs were exploited. The unmodified 2D materials offer remarkable simplicity in the layout and the use of ssDNAs as probes provides limitless possibilities because the natural interaction of a ssDNA and 2D surface can be fine-tuned with the nucleobase composition, oligonucleotide length and type of 2D nanomaterial. Therefore, the approach described here can be advanced and fine-tuned indefinitely for meeting a particular sensing criterion. Though we have only studied three distinct elements, this approach is universal enough to be applied to a wide-range of systems.

Functional TiO2 nanocoral architecture for light-activated cancer chemotherapy

To achieve light-triggered drug release in cancer chemotherapy, we developed multimodal titanium dioxide (TiO₂) nanocorals modified with methoxy polyethylene glycol (mPEG).

Rapid Visual Screening and Programmable Subtype Classification of Ebola Virus Biomarkers

The massive outbreaks of the highly transmissible and lethal Ebola virus disease were caused by infection with one of the Ebolavirus species. It is vital to develop cost-effective, highly sensitive and selective multitarget biosensing platforms that allow for both the detection and phenotyping. Here, a highly programmable, cost-efficient and multianalyte sensing approach is reported that enables visual detection and differentiation of conserved oligonucleotide regions of all Ebolavirus subtypes known to infect human primates. This approach enables the detection of as little as 400 amols (24 × 10⁶ molecules) of target sequences with the naked eye. Furthermore, the detection assay can be used to classify four virus biomarkers using a single nanoprobe template. This can be achieved by using different combinations of short single stranded initiator molecules, referred to as programming units, which also enable the simultaneous and rapid identification of the four biomarkers in 16 different combinations. The results of 16 × 5 array studies illustrate that the system is extremely selective with no false-positive or false-negative. Finally, the target strands in liquid biopsy mimics prepared from urine specimens are also able to be identified and classified.

Lipoproteins and lipoprotein mimetics for imaging and drug delivery

Lipoproteins are a set of natural nanoparticles whose main role is the transport of fats within the body. While much work has been done to develop synthetic nanocarriers to deliver drugs or contrast media, natural nanoparticles such as lipoproteins represent appealing alternatives. Lipoproteins are biocompatible, biodegradable, non-immunogenic and are naturally targeted to some disease sites. Lipoproteins can be modified to act as contrast agents in many ways, such as by insertion of gold cores to provide contrast for computed tomography. They can be loaded with drugs, nucleic acids, photosensitizers or boron to act as therapeutics. Attachment of ligands can re-route lipoproteins to new targets. These attributes render lipoproteins attractive and versatile delivery vehicles. In this review we will provide background on lipoproteins, then survey their roles as contrast agents, in drug and nucleic acid delivery, as well as in photodynamic therapy and boron neutron capture therapy.

Unlocked Nucleic Acids for miRNA detection using two dimensional nano-graphene oxide

In this study we have used Unlocked Nucleic Acids (UNAs) to discriminate a breast cancer oncomiR from two other miRNAs in the same RNA family using two-dimensional graphene oxide nanoassemblies. Fluorescently labeled single stranded probe strands and graphene oxide nanoassemblies have been used to detect miR-10b and discriminate it from miR-10a, which differs by only a single nucleotide (12th base from the 5' end), and miR-10c, which differs by only two nucleotides (12th and 16th bases from the 5' end). We have determined the discrimination efficacy and detection capacity of a DNA probe with two inserted UNA monomers (UNA₂), and compared it to the DNA probe with two purposefully inserted mutations (DNA_M2) and full complementary sequence (DNA_full). We have observed that UNA₂ is 50 times more powerful than DNA_full in discriminating miR-10b from miR-10c while generating an equally high fluorescence signal. This fluorescence signal was then further enhanced with the use of the highly specific endonuclease dsDNase for an enzymatic amplification step. The results demonstrate that the underutilized UNAs have enormous potential for miRNA detection and offer remarkable discrimination efficacy over single and double mismatches.

Ultrafine graphene oxide–CoFe2O4 nanoparticle composite as T1 and T2 contrast agent for magnetic resonance imaging

Graphene oxide–CoFe₂O₄ nanoparticle composites were synthesized using a two step synthesis method in which graphene oxide was initially synthesized followed by precipitation of CoFe₂O₄ nanoparticles in a reaction mixture containing graphene oxide.

Discriminating a Single Nucleotide Difference for Enhanced miRNA Detection Using Tunable Graphene and Oligonucleotide Nanodevices

In this study we have reported our efforts to address some of the challenges in the detection of miRNAs using water-soluble graphene oxide and DNA nanoassemblies. Purposefully inserting mismatches at specific positions in our DNA (probe) strands shows increasing specificity against our target miRNA, miR-10b, over miR-10a which varies by only a single nucleotide. This increased specificity came at a loss of signal intensity within the system, but we demonstrated that this could be addressed with the use of DNase I, an endonuclease capable of cleaving the DNA strands of the RNA/DNA heteroduplex and recycling the RNA target to hybridize to another probe strand. As we previously demonstrated, this enzymatic signal also comes with an inherent activity of the enzyme on the surface-adsorbed probe strands. To remove this activity of DNase I and the steady nonspecific increase in the fluorescence signal without compromising the recovered signal, we attached a thermoresponsive PEGMA polymer (poly(ethylene glycol) methyl ether methacrylate) to nGO. This smart polymer is able to shield the probes adsorbed on the nGO surface from the DNase I activity and is capable of tuning the detection capacity of the nGO nanoassembly with a thermoswitch at 39 °C. By utilizing probes with multiple mismatches, DNase I cleavage of the DNA probe strands, and the attachment of PEGMA polymers to graphene oxide to block undesired DNase I activity, we were able to detect miR-10b from liquid biopsy mimics and breast cancer cell lines. Overall we have reported our efforts to improve the specificity, increase the sensitivity, and eliminate the undesired enzymatic activity of DNase I on surface-adsorbed probes for miR-10b detection using water-soluble graphene nanodevices. Even though we have demonstrated only the discrimination of miR-10b from miR-10a, our approach can be extended to other short RNA molecules which differ by a single nucleotide.

Gold-graphene nanocomposites for sensing and biomedical applications

Recent developments in materials science and nanotechnology have propelled the development of a plethora of materials with unique chemical and physical properties for biomedical applications. Graphitic nanomaterials such as carbon nanotubes, fullerenes and, more recently, graphene oxide (GO) and reduced graphene oxide (rGO) have received a great deal of interest in this domain. Besides the exceptional physico-chemical features of these materials, another advantage is that they can be easily produced in good quantities. Moreover, the presence of abundant functional groups on their surface and good biocompatibility make them highly suitable for biomedical applications. Many research groups have utilized GO and rGO nanocargos to effectively deliver insoluble drugs, nucleic acids and other molecules into cells for bioimaging and therapeutic purposes. Gold nanostructures (Au NSs), on the other hand, have also attracted great attention owing to their applications in biomedical fields, organic catalysis, etc. Loading of GO and rGO sheets with Au NSs generates a new class of functional materials with improved properties and thus provides new opportunities in the use of such hybrid materials for catalytic biosensing and biomedical applications. This review article is aimed at providing an insight into the important features of gold-graphene nanocomposites, the current research activities related to the different synthetic routes to produce these nanocomposites, and their potential applications in sensing and biomedical therapy, notably photothermal therapy (PTT).

Monitoring the multitask mechanism of DNase I activity using graphene nanoassemblies

Here we have demonstrated that graphene serves as a remarkable platform for monitoring the multitask activity of an enzyme with fluorescence spectroscopy. Our studies showed that four different simultaneous enzymatic tasks of DNase I can be observed and measured in a high throughput fashion using graphene oxide and oligonucleotide nanoassemblies. We have used phosphorothioate modified oligonucleotides to pinpoint the individual and highly specific functions of DNase I with single stranded DNA, RNA, and DNA/DNA and DNA/RNA duplexes. DNase I resulted in fluorescence recovery in the nanoassemblies and enhanced the intensity tremendously in the presence of sequence specific DNA or RNA molecules with different degrees of amplification. Our study enabled us to discover the sources of this remarkable signal enhancement, which has been used for biomedical applications of graphene for sensitive detection of specific oncogenes. The significant difference in the signal amplification observed for the detection of DNA and RNA molecules is a result of the positive and/or reductive signal generating events with the enzyme. In the presence of DNA there are four possible ways that the fluorescence reading is influenced, with two of them resulting in a gain in signal while the other two result in a loss. Since the observed signal is a summation of all the events together, the absence of the two fluorescence reduction events with RNA gives a greater degree of fluorescence signal enhancement when compared to target DNA molecules. Overall, our study demonstrates that graphene has powerful features for determining the enzymatic functions of a protein and reveals some of the unknowns observed in the graphene and oligonucleotide assemblies with DNase I.

Reduced graphene oxide-supported gold nanostars for improved SERS sensing and drug delivery

Development of novel surface-enhanced Raman scattering (SERS) substrates and how they interface target analytes plays a pivotal role in determining the spectrum profile and SERS enhancement magnitude, as well as their applications. We present here the seed-mediated growth of reduced graphene oxide-gold nanostar (rGO-NS) nanocomposites and employ them as active SERS materials for anticancer drug (doxorubicin, DOX) loading and release. By this synthetic approach, both the morphology of rGO-NS nanohybrids and the corresponding optical properties can be precisely controlled, with no need of surfactant or polymer stabilizers. The developed rGO-NS nanohybrids show tunable optical properties by simply changing growth reaction parameters, improved stability as compared to bare Au nanostars, and sensitive SERS response toward aromatic organic molecules. Furthermore, SERS applications of rGO-NS to probe DOX loading and pH-dependent release are successfully demonstrated, showing promising potential for drug delivery and chemotherapy.

Simultaneous detection of circulating oncomiRs from body fluids for prostate cancer staging using nanographene oxide

Circulating oncomiRs are highly stable diagnostic, prognostic, and therapeutic tumor biomarkers, which can reflect the status of the disease and response to cancer therapy. miR-141 is an oncomiR, which is overexpressed in advanced prostate cancer patients, whereas its expression is at the normal levels in the early stages of the disease. On the other hand, miR-21 is significantly elevated in the early stage, but not in the advanced prostate cancer. Here, we have demonstrated simultaneous detection of exogenous miR-21 and miR-141 from human body fluids including blood, urine and saliva using nanographene oxide. Our system enables us to specifically and reliably detect each oncomiR at different fluorescence emission channels from a large population of RNAs extracted from body fluids. We were also able to determine the content and the ratio of the miR-21 and miR-141 in 10 different miRNA cocktails composed of various, but unknown, concentrations of both oncomiRs. A strong agreement (around 90%) between the experimental results and the actual miRNA compositions was observed. Moreover, we have demonstrated that overexpressed miR-21 or miR-141 increases the fluorescence only at their signature wavelengths of 520 and 670 nm, respectively. The approach in this study combines two emerging fields of nanographene in biomedicine and the role of circulating miRNAs in cancer. Our strategy has the potential to address the current challenges in diagnosis, prognosis and staging of prostate cancer with a non- or minimally invasive approach.

DNA-length-dependent quenching of fluorescently labeled iron oxide nanoparticles with gold, graphene oxide and MoS2 nanostructures

We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using three different nanomaterials with ultraefficient quenching capabilities. The control over the fluorescence emission was investigated via spacing introduced by the surface-functionalized single-stranded DNA molecules. DNA molecules were conjugated on different templates, either on the surface of the fluorescently labeled iron oxide nanoparticles or gold and nanographene oxide. The efficiency of the quenching was determined and compared with various fluorescently labeled iron oxide nanoparticle and nanoquencher combinations using DNA molecules with three different lengths. We have found that the template for DNA conjugation plays significant role on quenching the fluorescence emission of the fluorescently labeled iron oxide nanoparticles. We have observed that the size of the DNA controls the quenching efficiency when conjugated only on the fluorescently labeled iron oxide nanoparticles by setting a spacer between the surfaces and resulting change in the hydrodynamic size. The quenching efficiency with 12mer, 23mer and 36mer oligonucleotides decreased to 56%, 54% and 53% with gold nanoparticles, 58%, 38% and 32% with nanographene oxide, 46%, 38% and 35% with MoS2, respectively. On the other hand, the presence, not the size, of the DNA molecules on the other surfaces quenched the fluorescence significantly with different degrees. To understand the effect of the mobility of the DNA molecules on the nanoparticle surface, DNA molecules were attached to the surface with two different approaches. Covalently immobilized oligonucleotides decreased the quenching efficiency of nanographene oxide and gold nanoparticles to ∼22% and ∼21%, respectively, whereas noncovalently adsorbed oligonucleotides decreased it to ∼25% and ∼55%, respectively. As a result, we have found that each nanoquencher has a powerful quenching capability against a fluorescent nanoparticle, which can be tuned with surface functionalized DNA molecules.

Nano-graphene oxide as a novel platform for monitoring the effect of LNA modification on nucleic acid interactions

Graphene oxide has gained significant attention due to its exceptional physical properties at biological interfaces. It has extraordinary quenching, fast adsorption and desorption properties that are suitable for detection of molecular interactions in nucleic acids. Here we studied the interaction between locked nucleic acid (LNA) modified oligonucleotides and its complementary miR-10b DNA analog. We demonstrate that LNA modification does not alter the hybridization yield, despite a slight difference in the rate, however it does increase the duplex stability dramatically. The noncovalent nucleic acid-graphene oxide complex maintained the stability between 25 and 90 °C in the absence of oligonucleotide-induced desorption. The melting temperatures of duplexes with or without LNA base modification were determined due to remarkable fluorescence quenching and fast oligonucleotide adsorption with graphene oxide. The difference in melting temperatures was used to control the release of surface adsorbed nucleic acids at 70 °C. Finally, a mutation in the oligonucleotide sequence is detected by the complementary oligonucleotides on the graphene oxide surface. Due to its extraordinary physical properties, graphene oxide represents a remarkable platform for studying nucleic acid interactions and serves as a promising material for biomedical applications.