Biopolymer based nanomaterials in drug delivery systems: A review

Drug delivery systems (DDS) are used to achieve a higher therapeutic effects of a pharmaceutical drug or natural compound in a specific diseased site with minimal toxicological effect and these systems consists of liposomes, microspheres, gels, prodrugs and many. Nanotechnology is a rapidly developing multi-disciplinary science that ensures the fabrication of the polymers to nanometer scale for various medical applications. Uses of biopolymers in DDS ensure the biocompatibility, biodegradability and low immunogenicity over the synthetic ones. Biopolymers such as silk fibroins, collagen, gelatin, albumin, starch, cellulose and chitosan can be easily made into suspension that serve as delivery vehicles for both macro and mini drug molecules. There are various methods such as supercritical fluid extraction, desolvation, electrospraying, spray-drying, layer-by-layer self-assembly, freeze-drying and microemulsion introduced to make these DDS. This drug carrier systems enhance the drug delivery actively and can be used in ocular, transdermal, dental or intranasal delivery systems. This review describes the new trends in nanomaterials based drug delivery systems mainly using biopolymers such as proteins (silk fibroin, collagen, gelatin and albumin) and polysaccharides (chitosan, alginate, cellulose and starch).     

Selective adsorption of phosphate in water using lanthanum-based nanomaterials: A critical review

In recent years, lanthanum-based nanomaterials (La-NMs) are selected as an efficient nano-adsorbent for phosphate removal because La³⁺ has a strong affinity with oxygen-donor atoms from phosphate. Additionally, there are a broad interest and literature base for the effect of different synthesis optimization and environmental parameters on the adsorption performance of La-NMs. A considerable amount of research has also investigated the regeneration and application of La-NMs to real wastewater in a laboratory scale. Based on the literature survey, it was found that La-NMs are often produced via co-precipitation and hydrothermal methods. Moreover, phosphate's adsorption process and behavior onto La-NMs are described well with the pseudo-second-order model and Langmuir model. The interaction mechanism between phosphate and La-NMs are dominated by ligand exchange, surface complexation and electrostatic attraction. Furthermore, phosphate could easily desorb from La-NMs due to the weak H-bonding interaction between phosphate and the H-bond acceptor groups on the surface of La-NMs. Despite the wealth of literature available in this area, there is a lack of systematic review to evaluate the gaps in the use of La-NMs to eliminate phosphate in water. In this review, we mainly summarize and discuss the role and the effect of the synthesis techniques on the physicochemical properties and the adsorption behavior of La-NMs. The possible adsorption mechanism, regeneration efficiency, and the application of La-NMs to the real environmental samples are also presented and highlighted.     

Dielectrophoretic manipulation of nanomaterials: A review

Nanomaterials manipulation using dielectrophoresis (DEP) is one of the major research areas that could potentially benefit the micro/nano science for diverse applications, such as microfluidics, nanomachine, and biosensor. The innovation and development of basic theories, methods or applications will have a huge impact on the entire related field. Specifically, for DEP manipulation of nanomaterials, improvements in comprehensive performance of accuracy, flexibility and scale could promote broader applications in micro/nano science. Therefore, to explore the directions for future research, this paper critically provides an overview on the fundamentals, recent progress, current challenges, and potential applications of DEP manipulation of nanomaterials. This review will also act as a guide and reference for researchers to explore promising applications in relevant research.     

Carbon nanomaterials for salivary-based biosensors: a review

In recent years, saliva has been introduced as an alternate to conventional biofluid assays owing to both accessibility and reliability with regard to the assessment of different biomarkers. The capability of immediate online collection and analysis of salivary biomarkers offers myriad benefits for clinical applications, resulting in the demands for quantifying salivary biomarkers rapidly and reliably with the help of biosensing technology. Carbon–nanomaterial based biosensors provide potential instruments for a non-aggressive pain-free style of saliva-dependent recognition to diagnoses, monitor, and formulate a therapeutic modality and for managing patients. This review covers the importance of carbon nanomaterial in fabricating salivary-based detectors applied clinically for diagnostics and therapeutics. The utilization of carbon nanomaterials comprising carbon dots (CDs), carbon nanotubes (CNTs), graphene, graphene oxide (GO), reduced graphene oxide (rGO) and graphitic carbon nitride (g-C₃N₄) in salivary-based detection has been highlighted here with up-to-date instances. These sensing systems are capable of detecting a vast range of molecules with clinical relevance, including glucose, hormones, amino acids, viruses, bacteria, cancer antigens, cancer biomarkers, dopamine, sialic acid, uric acid, etc. which were discussed in this paper.     

Protein adsorption on the mesoporous molecular sieve silicate SBA-15: effects of pH and pore size

A mesoporous molecular sieve silicate, SBA-15, with three pore sizes (38.1 A, 77.3 A, and 240 A) has been synthesized using a non-ionic, tri-block copolymer as a template in a sol-gel method. The effects of synthesis conditions on the pore size and pore-size distribution of this adsorbent have been described. The adsorption of proteins on these crystalline, ordered, materials has been studied. The kinetics of adsorption and equilibrium capacity have been probed with three proteins of different dimensions. The effects of electrostatic interactions and protein size are illustrated. It has been shown that SBA-15 materials can be tailored to show size selectivity for proteins, and very high capacities (450 mg/g) can be obtained. Furthermore, the rates of adsorption are shown to be dependent on the pore size, protein structure and solution pH.     

Extracellular vesicles based electrochemical biosensors for detection of cancer cells: A review

Extracellular vesicles (EVs) derived from cancer cells are considered as ideal biomarker for liquid biopsy in cancer diagnosis, and are stable and abundant. Electrochemical methods for the detection of EVs are preferred over conventional methods such as Western blotting and enzyme-linked immunosorbent assay for their high sensitivity and real-time detection. This article summaries studies proposing the electrochemical methods utilizing immunological and molecular methodologies for detecting EVs derived biomacromolecules such as miRNAs and transmembrane protein for cancer diagnosis. Moreover, the electrochemical detection methods are compared and future prospects for the development of electrochemical methods for EVs detection are concluded.     

Protein adsorption in fused-silica and polyacrylamide-coated capillaries

The model proteins cytochrome c, myoglobin, ovalbumin, and beta-lactoglobulin were investigated with regard to their adsorption properties on capillaries for electrophoresis. The model compounds were selected to cover a wide range of properties. Cytochrome c is a basic protein (isoelectric point (pI): 9.6; M(r): 11.7 kDa), beta-lactoglobulin is rather acidic (pI: 5.4, M(r): 18.4 kDa), myoglobin was chosen as a neutral reference protein (pI: 6.8-7.4, M(r): 17.8 kDa), and ovalbumin (pI: 5.1, M(r): 45.0 kDa) was selected as a relatively larger analyte. First, the pH dependence of adsorption was investigated for the bare fused silica. A clear correlation to the respective pIs was noted. For myoglobin and ovalbumin, none or negligible adsorption was found above the pI, whereas strong adsorption was noted just below this parameter. Cytochrome c and beta-lactoglobulin already showed distinct adsorption above their pIs. However, none of the proteins showed any significant adsorption more than one pH unit above the pIs. For linear polyacrylamide-coated capillaries, a decreased but not a complete lack of adsorption was observed. Here, pH-dependent adsorption was noted as well. Regeneration of the capillaries by rinsing with buffers containing 200 mM SDS was also investigated. This method was completely successful for myoglobin, but that too for only freshly-adsorbed protein. After a storage time of 24 h and due to the aging of the adsorbate, a sufficient regeneration was no longer possible.     

Protein adsorption and transport in polymer-functionalized ion-exchangers

A wide variety of stationary phases is available for use in preparative chromatography of proteins, covering different base matrices, pore structures and modes of chromatography. There has recently been significant growth in the number of such materials in which the base matrix is derivatized to add a covalently attached or grafted polymer layer or, in some cases, a hydrogel that fills the pore space. This review summarizes the main structural and functional features of ion exchangers of this kind, which represent the largest class of such materials. Although the adsorption and transport properties may generally be used operationally and modeled phenomenologically using the same methods as are used for proteins in conventional media, there are noteworthy mechanistic differences in protein behavior in these adsorbents. A fundamental difference in protein retention is that it may be portrayed as partitioning into a three-dimensional polymer phase rather than adsorption at an extended two-dimensional surface, as applies in more conventional media. Beyond this partitioning behavior, however, the polymer-functionalized media often display rapid intraparticle transport that, while qualitatively comparable to that in conventional media, is sufficiently rapid quantitatively under certain conditions that it can lead to clear benefits in key measures of performance such as the dynamic binding capacity. Although possible mechanistic bases for the retention and transport properties are discussed, appreciable areas of uncertainty make detailed mechanistic modeling very challenging, and more detailed experimental characterization is likely to be more productive.     

The nanomaterials and recent progress in biosensing systems: A review

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A mini review of nanomaterials on photodynamic therapy

In this account, the reactive oxygen species (ROS) in photodynamic therapy (PDT) were deliberately reviewed. First, the specific definition of ROS and PDT were readily clarified. Afterward, this review focuses on the fundamental principles and applications of PDT. Due to strong oxidation ability of radicals (e.g., •OH and O₂^•-) and non-radical (e.g., ¹O₂ and H₂O₂), these ROS would attack the in vitro and in vivo tumor cells, thus achieving the goal of cancer treatment. Then, ROS in PDT for cancer treatment was thoroughly reviewed, including the mechanism and photosensitizer (PS) selection (i.e., nanomaterials). Ultimately, emphasis was made on the challenges, research gap, and prospects of ROS in cancer treatment and critically discussed. Hopefully, this review can offer detailed theoretical guidance for the researchers who participate in the study regarding ROS in PDT.     

Recent advances in the development of polydiacetylene-based biosensors

Biosensors that effectively and selectively detect biomolecules and monitor biological processes have become an important component of biological and medical studies. Because they possess several attractive features, polydiacetylenes(PDAs) have been employed as frameworks for fluorometric and colorimetric sensors. PDAs are formed in their non-fluorescent blue-colored state by UV light induced polymerization of head group functionalized diacetylene monomers(DAs) and they undergo a transition to form fluorescent red-colored PDAs in response to a variety of stimuli. Importantly, by properly choosing a headgroup in the DA, the formed PDA can be designed to undergo a fluorescence/colorimetric change in response to a specific biological stimulus. This review summarizes recent advances that have been made in the development of PDA biosensors with an emphasis being given to design strategies and applications.     

Trends in the development of nucleic acid biosensors for medical diagnostics

Some of the recent advances in the field of biosensors for nucleic acid analysis in medical diagnostic applications are highlighted. Particular attention is paid in this review to the progress made in two key areas of development: (i) enhancements achieved in device selectivity, and (ii) enhancements achieved in device sensitivity.     

Recent advances in the development of polydiacetylene-based biosensors

The review summarizes efforts made in the development of polydiacetylene based biosensors for assaying enzyme activities, targeting tumors, imaging cells, monitoring cellular activities, and detecting microorganisms and biomolecules.     

Tetracyclines adsorption onto alumina: A comparative experimental and molecular dynamics simulation study

Using alumina (Al₂O₃) as the adsorbent, a static adsorption experiment was carried out in this study. It comprehensively evaluated the factors including Al₂O₃ dosage, adsorption temperature, and pH that influence the adsorption capability of three tetracyclines (TCs), namely, tetracycline hydrochloride (TC), chlortetracycline hydrochloride (CTC) and oxytetracycline hydrochloride (OTC). The results demonstrate that the adsorption efficiency increases with Al₂O₃ dosage. In addition, low-acid or natural solution is benefit for the adsorption. The adsorption behavior is more reasonably described with the Freundlich isotherm, and fits well with the pseudo-second-order kinetic model (R²?>?0.999). The results of molecular dynamics (MD) simulation show that the structures of TCs deformed during the combining process. The values of binding energy of TCs follow the order as: CTC (88.45?kcal/mol)?>?OTC (73.54?kcal/mol)?>?TC (54.28?kcal/mol). The MD simulation results agree well with the adsorption experimental results, which indicates that the MD simulation is reliable and reasonable. The MD simulation will provide theoretical knowledge in understanding the adsorption mechanism and environmental behavior of TCs.     

A novel analytical approach for investigation of anthracene adsorption onto mangrove leaves

A solid surface fluorimetry approach was established for direct determination of anthracene (An) adsorbed onto fresh mangrove leaves. The experimental results showed that the linear dynamic ranges for determination of An adsorbed onto Avicennia marina (Am), Bruguiera gymnorrhiza (Bg), Kandelia candel (Kc) and Rhizophors stylosa (Rs) leaves varied from 0.92 to 8.71, 0.089 to 0.70, 0.063 to 5.61 and 0.11 to 1.82 microgg(-1), with detection limits of 5.77, 1.79, 4.29 and 1.42 ngg(-1), respectively, and with a relative standard deviation less than 10% (n=5). The experimental recovery results for adsorbed An on Am, Bg, Kc and Rs leaves were among 79.2-85.9, 75.1-102.3, 70.2-93.8 and 73.1-110.8%, respectively. Using the established method, we investigated the effects of exposure time of An and the different quantity of leaf-wax among the four species of mangrove on the amount of An adsorbed. Under the same experimental conditions, the adsorption of An on the upper and lower sides of the same mangrove leaf, and at different regions on the upper side of the same mangrove leaf were also studied. The results demonstrated that the leaves of different mangrove species contained different quantities of leaf-wax, and with the same exposure conditions to An, the quantity of leaf-wax among the four species showed a significant positive correlation with the amount of An adsorbed onto the leaves.     

Tethered thiazole orange intercalating dye for development of fibre-optic nucleic acid biosensors

Single-stranded DNA (ssDNA) oligonucleotide in solution, or that is immobilized onto a surface to create a biosensor, can be used as a selective probe to bind to a complementary single-stranded sequence. Fluorescence enhancement of thiazole orange (TO) occurs when the dye intercalates into double-stranded DNA (dsDNA). TO dye has been covalently attached to probe oligonucleotides (homopolymer and mixed base 10mer and 20mer) through the 5′ terminal phosphate group using polyethylene glycol linker. The tethered TO dye was able to intercalate when dsDNA formed in solution, and also at fused silica surfaces using immobilized ssDNA. The results indicated the potential for development of a self-contained biosensor where the fluorescent label was available as part of the immobilized oligonucleotide probe chemistry. The approach was shown to be able to operate in a reversible manner for multiple cycles of detection of targeted DNA sequences.     

Adsorption studies of polyethers Part II: adsorption onto hydrophilic surfaces

The adsorption of BAB-type triblock copolymers (B=poly(ethylene oxide); A=poly(propylene oxide)) from aqueous solution onto hydrophilic silica particles is described with particular reference to the role of the copolymer composition. The adsorbed amount and the layer thickness were determined by the standard depletion method and photon correlation spectroscopy, respectively. Snowtex-YL silica was used as the adsorbent. The results show an increase in the adsorbed amount with increasing molar masses of both PEO and PPO blocks. The adsorbed layer thickness is found to depend strongly on PEO block mass. Both these parameters (adsorbed amount and hydrodynamic layer thickness) show a maximum as a function of the mole fraction of the PPO block present in the copolymer. The conformation of the adsorbed layer is determined by the surface–copolymer interaction; principally by the interaction of the hydrophilic PEO block with the silica surface. A good qualitative agreement of the experimental results with theoretical predictions and self-consistent mean field calculations has been found.     

Comparison of analytical methods for ozone precursors using adsorption tube and canister

Recently, ozone concentrations have increased dramatically as a result of vehicle usage in metropolitan areas. Ozone precursors are composed of hydrocarbons of organic compounds. Because hydrocarbons are indicative of ozone formation, they need to be monitored in ambient air. Since ozone precursor are present at very low levels (from ppb to ppt) in ambient air, they are difficult to analyze accurately. This study investigates ozone precursors in ambient air. The main purpose of this study is to compare analytical methods for the measurement of ozone precursors in atmosphere. Two measurement methods were evaluated using canister (Silco-canister) and adsorbent (300-mg Carbopack B+150-mg Carbosieve SIII) tube. Differences in measurements for total ozone precursor emissions were 54.1% between the adsorption tube and canister-GC/MS, 51.1% between adsorption tube and canister-GC/FID, and 16.3% between canister-GC/MS and canister-GC/FID.