A molecularly imprinted polymer (MIP) was developed for the electrochemical determination of the antiviral drug sofosbuvir (SOF). The MIP was obtained by polymerization of p-aminothiophenol (p-ATP) on N,S co-doped graphene quantum dots (N,S@GQDs) in the presence of gold nanoparticles to form gold-sulfur covalent network. The presence of quantum dots improves the electron transfer rate, enhances surface activity and amplifies the signal. The nanocomposites were characterized by FTIR, TEM, EDX, and SEM. The electrochemical performance of the electrode was investigated by differential pulse voltammetry and cyclic voltammetry. The sensor uses hexacyanoferrate as the redox probe and is best operated at a potential of around 0.36 V vs. Ag/AgCl. It has a linear response over the concentration range of 1–400 nM SOF, with a detection limit of 0.36 nM. Other features include high selectivity, good reproducibility and temporal stability. The sensor was applied to the determination of SOF in spiked human plasma.

A novel green magnetic molecularly imprinted solid phase extraction (MMI-SPE) for separation of memantine (MEM) from complicated matrices was proposed. The nanomaterial was synthesized via crosslinking of chitosan (CHIT) with [3-(2, 3-epoxypropoxy)-propyl] trimethoxysilane (EPPTMS) in presence of MEM as a template. The nanocomposites, in all steps, were characterized by SEM, FTIR and PXRD techniques. The adsorbed drug was removed from magnetic molecular imprinted polymer (MMIP) cavity by ethanol: acetic acid (8:2, v/v) and then, coupled with sodium 1,2-naphthoquinone-4-sulphonate (NQS) in iodine/alkaline medium to yield highly fluorescent product, after reduction with potassium borohydride (KBH4). Variables affecting extraction of MEM from imprinted sites and its fluorometric analysis were studied. The linearity was achieved over concentration range of 1.84–95.0 ng mL−1 with LOD of 0.6 ng mL−1. The method was successfully applied for determination of MEM in its pharmaceutical tablets and human serum with recoveries of 100.8 ± 3.0, 97.6 ± 2.9, respectively.

A novel green magnetic molecularly imprinted solid phase extraction (MMI-SPE) for separation of memantine (MEM) from complicated matrices was proposed. The nanomaterial was synthesized via crosslinking of chitosan (CHIT) with [3-(2, 3-epoxypropoxy)-propyl] trimethoxysilane (EPPTMS) in presence of MEM as a template. The nanocomposites, in all steps, were characterized by SEM, FTIR and PXRD techniques. The adsorbed drug was removed from magnetic molecular imprinted polymer (MMIP) cavity by ethanol: acetic acid (8:2, v/v) and then, coupled with sodium 1,2-naphthoquinone-4-sulphonate (NQS) in iodine/alkaline medium to yield highly fluorescent product, after reduction with potassium borohydride (KBH4). Variables affecting extraction of MEM from imprinted sites and its fluorometric analysis were studied. The linearity was achieved over concentration range of 1.84–95.0 ng mL−1 with LOD of 0.6 ng mL−1. The method was successfully applied for determination of MEM in its pharmaceutical tablets and human serum with recoveries of 100.8 ± 3.0, 97.6 ± 2.9, respectively.

A novel green magnetic molecularly imprinted solid phase extraction (MMI-SPE) for separation of memantine (MEM) from complicated matrices was proposed. The nanomaterial was synthesized via crosslinking of chitosan (CHIT) with [3-(2, 3-epoxypropoxy)-propyl] trimethoxysilane (EPPTMS) in presence of MEM as a template. The nanocomposites, in all steps, were characterized by SEM, FTIR and PXRD techniques. The adsorbed drug was removed from magnetic molecular imprinted polymer (MMIP) cavity by ethanol: acetic acid (8:2, v/v) and then, coupled with sodium 1,2-naphthoquinone-4-sulphonate (NQS) in iodine/alkaline medium to yield highly fluorescent product, after reduction with potassium borohydride (KBH4). Variables affecting extraction of MEM from imprinted sites and its fluorometric analysis were studied. The linearity was achieved over concentration range of 1.84–95.0 ng mL−1 with LOD of 0.6 ng mL−1. The method was successfully applied for determination of MEM in its pharmaceutical tablets and human serum with recoveries of 100.8 ± 3.0, 97.6 ± 2.9, respectively.

Carbon dots doped with copper(II) and nitrogen (Cu,N@C-dots) were prepared and are shown to be viable fluorescent nanoprobe for pyrogallol (PGL) was developed for the first time. The reaction is based on (a) the complexation reaction between Cu,N@C-dots and catechol moiety, and (b) the generation of a quinone-like structure. Thus, the co-ordination complex formed between Cu(II) in C-dots and PGL results in quenching of the fluorescence of C-dots. In addition, the formation of a yellow color due to complex formation between the nanoprobe and Cu(II) allowed the colorimetric determination of PGL. The nanoprobe was prepared by thermal synthesis, using ethylenediaminetetraacetic acid salt and copper(II) chloride as sources for carbon, nitrogen and copper, respectively. The carbon dots were characterized by UV-VIS spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, transmission electron microscopy) and dynamic light scattering. Fluorescence drops linearly in the 0.15 to 70 μM PGL concentration range with a detection limit of 39 nM and a relative standard deviation of 1.8%. The optimal excitation and emission wavelengths are 370 nm and 428 nm, respectively. The colorimetric assay has a linear response at 325 nm absorption wavelengths in the 6 to 140 μM PGL concentration range with a detection limit of 1.8 μM and a 2.3% relative standard deviation. Open image in new window

Carbon dots doped with copper(II) and nitrogen (Cu,N@C-dots) were prepared and are shown to be viable fluorescent nanoprobe for pyrogallol (PGL) was developed for the first time. The reaction is based on (a) the complexation reaction between Cu,N@C-dots and catechol moiety, and (b) the generation of a quinone-like structure. Thus, the co-ordination complex formed between Cu(II) in C-dots and PGL results in quenching of the fluorescence of C-dots. In addition, the formation of a yellow color due to complex formation between the nanoprobe and Cu(II) allowed the colorimetric determination of PGL. The nanoprobe was prepared by thermal synthesis, using ethylenediaminetetraacetic acid salt and copper(II) chloride as sources for carbon, nitrogen and copper, respectively. The carbon dots were characterized by UV-VIS spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, transmission electron microscopy) and dynamic light scattering. Fluorescence drops linearly in the 0.15 to 70 μM PGL concentration range with a detection limit of 39 nM and a relative standard deviation of 1.8%. The optimal excitation and emission wavelengths are 370 nm and 428 nm, respectively. The colorimetric assay has a linear response at 325 nm absorption wavelengths in the 6 to 140 μM PGL concentration range with a detection limit of 1.8 μM and a 2.3% relative standard deviation. Open image in new window

An innovative electrochemical sensor was proposed for simultaneous determination of mycophenolate mofetil (Mph) and tacrolimus (TAC) for the first time. A novel sensor based on electro-polymerization of multi-walled carbon nanotubes (MWCNTs) and a novel Cu-1N-allyl-2-(2,5-dimethoxyphenyl)-4,5-diphenyl-1H-imidazole metal organic framework (Cu-ADPPI MOF) on disposable pencil graphite electrode (dPGE). Many techniques were used to characterize the electrochemical activity and surface structure of the fabricated sensor. The proposed sensor exhibited good catalytic performance towards Mph and TAC oxidation due to the synergistic effect. Under optimal conditions, the proposed sensor has achieved a linear range of 0.85–155 × 10−8 M and 1.1–170.0 × 10−8 M with LODs of 0.28 × 10−8 M and 0.36 × 10−8 M for Mph and TAC, respectively. The designated sensor showed good reproducibility, repeatability, stability, and selectivity for the determination of Mph and TAC. Moreover, the simultaneous determination of Mph and TAC in different human biological fluids was carried out with acceptable results. As a result, the proposed sensor opens a new venue for the use of electro-polymerized MOFs in combination with other conductive materials such as MWCNTs for electrochemical sensing of different analytes with the desired sensitivity and selectivity.

An innovative electrochemical sensor was proposed for simultaneous determination of mycophenolate mofetil (Mph) and tacrolimus (TAC) for the first time. A novel sensor based on electro-polymerization of multi-walled carbon nanotubes (MWCNTs) and a novel Cu-1N-allyl-2-(2,5-dimethoxyphenyl)-4,5-diphenyl-1H-imidazole metal organic framework (Cu-ADPPI MOF) on disposable pencil graphite electrode (dPGE). Many techniques were used to characterize the electrochemical activity and surface structure of the fabricated sensor. The proposed sensor exhibited good catalytic performance towards Mph and TAC oxidation due to the synergistic effect. Under optimal conditions, the proposed sensor has achieved a linear range of 0.85–155 × 10−8 M and 1.1–170.0 × 10−8 M with LODs of 0.28 × 10−8 M and 0.36 × 10−8 M for Mph and TAC, respectively. The designated sensor showed good reproducibility, repeatability, stability, and selectivity for the determination of Mph and TAC. Moreover, the simultaneous determination of Mph and TAC in different human biological fluids was carried out with acceptable results. As a result, the proposed sensor opens a new venue for the use of electro-polymerized MOFs in combination with other conductive materials such as MWCNTs for electrochemical sensing of different analytes with the desired sensitivity and selectivity.

Introduction: The discovery of RNA interference (RNAi) earned the 2006 Nobel Prize in Physiology or Medicine for its biological significance and potential for developing novel therapeutics. The small interfering RNA (siRNA) is the most promising tool for translating RNAi to clinical use. Efforts are ongoing to improve siRNA delivery through developing novel biomaterials and delivery strategies. Given time, it appears that siRNA drugs will eventually become a reality. Areas covered: The currently used approaches for siRNA delivery are discussed with a focus on siRNA therapeutics currently in clinical testing. A comparison of advantageous aspects of currently available platforms and the possibility of further optimization for increased efficiency and safety are presented. Future directions in siRNA delivery are also highlighted. Expert opinion: The recent success in the field of siRNA delivery is based mainly on developing new biomaterials with extraordinarily high activities. Notably, the introduction of ionizable lipids and novel targeting ligands represent two huge steps for realizing siRNA therapy. The currently available systems are largely directed to the liver and the new challenge is to extend their applicability for treating diseases of other organs. Active targeting to different organs is the most promising approach for developing new siRNA-based therapeutics.

In plants, prenylation of metabolites is widely distributed to generate compounds with efficient defense potential and distinct pharmacological activities profitable to human health. Prenylated compounds are formed by members of the prenyltransferase (PT) superfamily, which catalyze the addition of prenyl moieties to a variety of acceptor molecules. Cell cultures of Hypericum calycinum respond to elicitor treatment with the accumulation of the prenylated xanthone hyperxanthone E. A cDNA encoding a membrane-bound PT (HcPT) was isolated from a subtracted cDNA library and transcript preparations of H. calycinum. An increase in the HcPT transcript level preceded hyperxanthone E accumulation in cell cultures of H. calycinum treated with elicitor. The HcPT cDNA was functionally characterized by expression in baculovirus-infected insect cells. The recombinant enzyme catalyzed biosynthesis of 1,3,6,7-tetrahydroxy-8-prenylxanthone through regiospecific C–8 prenylation of 1,3,6,7-tetrahydroxyxanthone, indicating its involvement in hyperxanthone E formation. The enzymatic product shared significant structural features with the previously reported cholinesterase inhibitor γ-mangostin. Thus, our findings may offer a chance for semisynthesis of new active agents to be involved in the treatment of Alzheimer’s disease.