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Topic Review
Benzodiazepine Dependence
Benzodiazepine dependence defines a situation in which one has developed one or more of either tolerance, withdrawal symptoms, drug seeking behaviors, such as continued use despite harmful effects, and maladaptive pattern of substance use, according to the DSM-IV. In the case of benzodiazepine dependence, however, the continued use seems to be associated with the avoidance of unpleasant withdrawal reaction rather than from the pleasurable effects of the drug. Benzodiazepine dependence develops with long-term use, even at low therapeutic doses, without the described dependence behavior. Addiction consists of people misusing or craving the drug not to relieve withdrawal symptoms, but to experience its euphoric or intoxicating effects. It is necessary to distinguish between addiction to and abuse of benzodiazepines and physical dependence on them. The increased GABA inhibition on the neural systems caused by benzodiazepines is counteracted by the body's development of tolerance to the drug's effects; the development of tolerance occurs as a result of neuroadaptations, which result in decreased GABA activity and increased excitability of the glutamate system; these adaptations occur as a result of the body trying to overcome the central nervous system depressant effects of the drug to restore homeostasis. When benzodiazepines are stopped, these neuroadaptations are "unmasked" leading to hyper-excitability of the nervous system and the appearance of withdrawal symptoms. Therapeutic dose dependence is the largest category of people dependent on benzodiazepines. These individuals typically do not escalate their doses to high levels and generally use their medication as intended by their prescriber. Smaller groups include patients escalating their dosage to higher levels and drug misusers as well. Tolerance develops within days or weeks to the anticonvulsant, hypnotic, muscle relaxant and after 4 months there is little evidence that benzodiazepines retain their anxiolytic properties. Some authors, however, disagree and feel that benzodiazepines retain their anxiolytic properties. Long-term benzodiazepine treatment may remain necessary in certain clinical conditions. Numbers of benzodiazepine prescriptions have been declining, due primarily to concerns of dependence. In the short term, benzodiazepines can be effective drugs for acute anxiety or insomnia. With longer-term use, other therapies, both pharmacological and psychotherapeutic, become more effective. This is in part due to the greater effectiveness over time of other forms of therapy, and also due to the eventual development of pharmacological benzodiazepine tolerance.
  • 1.2K
  • 18 Nov 2022
Topic Review
A Graphene-PEDOT
A graphene and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) modified conductive paper-based electrochemical impedance spectroscopy (EIS) aptasensor has been successfully fabricated by a simple and continuous coating process. A graphene/PEDOT:PSS modified paper electrode forms the nanocomposite providing a conductive and sensitive substrate for further aptamer functionalization of the biosensor. This low-cost paper-based aptasensor exhibits its sensitivity to carcinoembryonic antigens (CEA) in standard buffer solutions and human serum samples in a linear range of 0.77–14 ng·mL−1. The limit of detection (LOD) is found to be 0.45 ng·mL−1 and 1.06 ng·mL−1 for CEA in both samples, separately. This aptamer-based sensing device was also evaluated and received a good correlation with the immunoassay detection method. The proposed paper-based aptasensor has demonstrated its potential as a rapid simple point-of-care analytical platform for early cancer diagnosis in less developed areas where manufacturing facilities, analytical instruments, and trained specialists are limited.
  • 1.2K
  • 01 Nov 2020
Topic Review
Phase-Change Materials
Phase-change materials (PCMs) are important photonic materials that have the advantages of a rapid and reversible phase change, a great difference in the optical properties between the crystalline and amorphous states, scalability, and nonvolatility. 
  • 1.2K
  • 19 May 2021
Topic Review
Chemical Enzymology of Monoamine Oxidase
Monoamine oxidase (E.C. 1.4.3.4) enzymes MAO A and MAO B are FAD-containing proteins located on the outer face of the mitochondrial inner membrane, retained there by hydrophobic interactions and a transmembrane helix. The redox co-factor (FAD) is covalently attached to a cysteine and buried deep inside the protein behind an aromatic cage that aligns substrates towards the flavin. MAO metabolizes neurotransmitters such as dopamine and serotonin in the nervous system so is a target for drugs to modify amine levels. MAO also metabolizes a wide range of biogenic amines in all tissues. Current accumulated evidence, particularly from theoretical modelling, supports hydride transfer as the chemical mechanism. The long active site cavity accommodates a wide chemical variety of small molecules designed as inhibitors, including coumarins, chromones, triazoles, and more. Inactivators that bind covalently to MAO include hydrazines, cyclopropylamines and propargylamines. This entry is an extract adapted from a review outlining the remaining uncertainties in the understanding of this key drug target.
  • 1.2K
  • 19 Oct 2021
Topic Review
Covalent Organic Framework Composites
Covalent organic frameworks (COFs) are crystalline, porous materials formed by the self-assembly of organic building blocks. Composite materials containing COFs have raised increasing interest. To date, various synthesis techniques have emerged that allow for the preparation of crystalline and porous COF composites with different materials offering highly efficient tools for analytical applications.
  • 1.2K
  • 08 Mar 2021
Topic Review
Synthesis of Mesoporous Silica Nanoparticles
Mesoporous silica nanoparticles (MSNs) have been advocated as nanocarriers for the treatment of various diseases because of their physicochemical properties and biocompatibility. The use of MSNs combined with therapeutic agents can provide better encapsulation and effective delivery. MSNs as nanocarriers might also be a promising tool to lower the therapeutic dosage levels and thereby to reduce undesired side effects. Furthermore, when combined with imaging compounds for diagnosis, they can be employed as theragnostic agents thus allowing both imaging and therapy using the same nanoparticle.
  • 1.2K
  • 19 Jul 2023
Topic Review
Nanocellulose-Reinforced Rubber Matrix Composites
Research and development of nanocellulose (NC) and nanocellulose-reinforced composite materials have garnered substantial interest in recent years. Rubber is a common material with a large array of applications, greatly attributed to its mechanical strength and versatility. When rubber is extracted from its natural source, it needs to undergo a compounding stage where fillers are added to reinforce the material prior to further processing. The application of nanocellulose and its variants as a substitute of conventional fillers like carbon black (CB) and silica could further reduce environmental impacts and cost as it is derived from organic biomass. Incorporation of nanocellulose as a reinforcing material could also be extended to synthetic rubber composites to carry out a similar function of improving mechanical integrity.
  • 1.2K
  • 04 Mar 2021
Topic Review
Electrochemical Biosensor
Electrochemical Biosensor can be used to detect low concentrations of analytes.
  • 1.2K
  • 22 Jul 2021
Topic Review
Sterilization in Endodontic Instruments
Sterilization processes guarantee the sterility of dental instruments but can negatively affect instrument features by altering their physical and mechanical properties. The endodontic instrumentation can undergo a series of alterations, ranging from corrosion to variation in the cutting angle and then changes in the torsional properties and torsional fatigue resistance.
  • 1.2K
  • 06 Apr 2021
Topic Review
Thermal Analysis to 3D Printing
Thermal analysis (TA) comprises various measuring techniques with a common feature: the measure of the material response when heated or cooled (or, in some cases, held isothermally).
  • 1.2K
  • 29 Mar 2022
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