Physiological Phosphate-buffered Saline Research Articles

An AIE-Active NIR Fluorescent Probe with Good Water Solubility for the Detection of Aβ1-42 Aggregates in Alzheimer's Disease.

Alzheimer's disease (AD), an amyloid-related disease, seriously endangers the health of elderly individuals. According to current research, its main pathogenic factor is the amyloid protein, which is a kind of fibrillar aggregate formed by noncovalent self-assembly of proteins. Based on the characteristics of aggregation-induced emission (AIE), a bislactosyl-decorated tetraphenylethylene (TPE) molecule TMNL (TPE + malononitrile + lactose), bearing two malononitrile substituents, was designed and synthesized in this work. The amphiphilic TMNL could self-assemble into fluorescent organic nanoparticles (FONs) with near-infrared (NIR) fluorescence emission in physiological PBS (phosphate buffered saline), achieving excellent fluorescent enhancement (47-fold) upon its combination with Aβ1-42 fibrils. TMNL was successfully applied to image Aβ1-42 plaques in the brain tissue of AD transgenic mice, and due to the AIE properties of TMNL, no additional rinsing process was necessary. It is believed that the probe reported in this work should be useful for the sensitive detection and accurate localization mapping of Aβ1-42 aggregates related to Alzheimer's disease.

Highly Sensitive Detection of the Antidepressant Fluoxetine With an Extended Gate Field Effect Transistor

Fluoxetine (FL) is one of the selective serotonin reuptake inhibitors, which is used as an anti-depressant, as well as anti-panic drug. In this work, a sensor for label-free recognition of trace amounts of FL is introduced, which is based on an extended gate field-effect transistor (EGFET). This sensor enables the detection and accurate measurement of FL concentrations over wide dynamic range. The sensing part of the device is a Pt electrode covered by a sensitive polyvinyl chloride (PVC) membrane. The functionalized Pt electrode acting as an extended gate of the EGFET, is connected to the internal gate of a MOSFET transducer. The sensing element of the PVC membrane is the insoluble ion-pair of FL cation and tetraphenylborate anion. The sensor performance for detection of FL was characterized in different ionic strengths of the matrix solution. Then, the sensor capability to operate in physiological phosphate-buffered saline (PBS) was assessed, where the sensor indicated two linear dynamic ranges of its response, with different sensitivities in 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−11</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> M and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> M ranges. Also the calculated detection limit for the sensor was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.63\times 10^{-12}$ </tex-math></inline-formula> M. Moreover, the selectivity of the sensor was examined and validated in the presence of Citalopram, which is another anti-depressant drug with a similar structure to FL. We proposed a comprehensive analytical mapping of current sensitivity in all working regimes of the EGFET, providing a guide to the design of optimized sensors in any integrated systems of interest. Finally, the sensor was successfully exploited to assay citalopram in its pharmaceutical formulation.

Tendon Multiscale Structure, Mechanics, and Damage Are Affected by Osmolarity of Bath Solution.

One of the most common bath solutions used inmusculoskeletal mechanical testing is phosphate buffered saline (PBS). In tendon, swelling induced by physiological PBS results in decreased tendon modulus and induces microstructural changes. It is critical to evaluate the multiscale mechanical behavior of tendon under swelling to interpret prior work and provide information to design future studies. We compared the effects of physiological PBS and 8% polyethylene glycol and saline bathing solutions on tendon multiscale tendon mechanics and damage as well as microstructure with TEM in order to understand the effect of swelling on tendon. At the tissue level, tendons in PBS had a lower modulus than SPEG samples. PBS samples also showed an increased amount of non-recoverable sliding, which is an analog for microscale damage. SPEG had a higher microscale to tissue-scale strain ratio, showing the fibrils experienced less strain attenuation. From the TEM data, we showed the fibril spacing of SPEG samples was more similar to fresh control than PBS. We concluded that swelling alters multiscale mechanics and damage in addition to tendon microstructure. Future mechanical testing should consider using SPEG as a bath solution with an osmotic pressure which preserves fresh tissue water content.

A Simple Injectable Moldable Hydrogel Assembled from Natural Glycyrrhizic Acid with Inherent Antibacterial Activity.

Injectable low-molecular-weight hydrogels (LMWHs) from biocompatible materials have attracted much attention in biomedical applications because they can adapt any desired sizes and cavity shapes. Searching for simple, biocompatible injectable LMWHs owning inherent antibacterial activity without complicated chemical modification remains an open question to avoid the tedious synthesis/purification process and the easy bacterial infection of hydrogels in a moist environment. In this work, glycyrrhizic acid (GL), a naturally occurring compound, was found to form a stable transparent LMWH at 37 °C in physiological phosphate buffered saline (PBS) with nanoclusters as the microstructures. Moreover, this hydrogel exhibited great injectable and moldable properties. The antibacterial study showed that the growth of Gram-positive Staphylococcus aureus (S. aureus) could be completely inhibited by GL, whereas noneffect on Gram-negative Escherichia coli (E. coli) was observed. In addition, cell viability and hemolysis assay revealed that GL had good biocompatibility and hemocompatibility to mammalian cells because of its natural origin. Our simple biocompatible injectable moldable LMWH with inherent antibacterial ability has potential in the area of biomaterials and 3D bioprinting.

Endogenous Biomaterials for Implantable Energy Storage

The United States National Academy of Engineering has included the need to “Advance health informatics” among its 14 Grand Challenges for Engineering in the 21st Century. Bioelectronics, in concert with the Internet of Things, which seeks to enable the facile integration of implantable devices with “big data”-driven health monitoring, promises to empower personalized healthcare. For example, advances in bioelectronics have produced implantable devices for in vivo biosensing, monitoring, and therapeutics that are fabricated with biocompatible materials and seamlessly interface with biological systems and living tissue, and could therefore have enormous utility for “precision medicine”. In contrast, the field of implantable energy storage is relatively unexplored. Batteries for implantable devices currently require bulky casing because they contain toxic electrolytes and non-endogenous active materials that elicit immune responses which negatively impact device performance and long-term functionality. Therefore, development of new materials is paramount for safety and miniaturization. Ideally, implantable devices could achieve maximum biocompatibility if they exclusively comprised endogenous materials. In this context, dopamine is an electroactive, essential neurotransmitter that exhibits catechol/quinone redox functionality, and is thus an excellent candidate for implantable energy-storage. However, electronics and batteries for implantable medical devices must also resist nonspecific protein adsorption, as biofouling is the primary contributor to decreased sensitivity of implantable devices such as glucose sensors. Biological hydrogels have proven useful for masking implantable devices since they are soft, elastic, and highly permeable to low molecular weight molecules; they also effectively resist the non-specific protein adsorption that leads to cell adhesion and biofouling. To combine the electroactive properties of dopamine and the non-adhesive biocompatibility of hydrogels, we chemically conjugated hyaluronic acid (HA) and dopamine (DA) via one-step carbodiimide conjugation to form an electroactive biocomposite. Hyaluronic acid is an endogenous polysaccharide found throughout human endothelial and neural tissues, and is a primary constituent of the extracellular matrix. It has well-characterized properties, is generally non-adhesive to cells, and inhibits glial cell response. The dopamine-hyaluronic acid (DAHA) composite can be electrodeposited onto electronically conducting substrates to form an electroactive polydopamine-hyaluronic acid (p(DAHA)) biopolymer for bioelectronic energy storage. The pseudocapacitive p(DAHA) exhibits catechol-quinone interconversion, stable, long-term electroactivity for 400 cycles, and high pseudocapacitance (up to ~ 900 F g-1) and discharge capacity (~ 130 mAh g-1 at ~ 10 A g-1) in physiological phosphate-buffered saline solution. These characteristics predispose it for bioelectronic energy storage, i.e., as a supercapacitor or, when coupled with an implantable Ag/AgCl electrode, a biobattery with an operating voltage ~ 0.85 V.

Impedimetric investigation of dual electrical properties of reduced graphene-oxide-based biosensors in the detection of dopamine.

Because of the properties of high charge mobility, large detection area and chemical stability of graphene, it has been applied in many biomedical applications. Graphene oxide (GO) with abundant oxygenated functional groups is easily to form an aqueous suspension by sonication. Here, the exposed areas on the patterned-circuit silicon-based chips were first modified by (3-aminopropyl) trimethoxysilane (APTMS) for later chemically immobilized GO. After that, solution-based reduction process using hydrazine was used to gain reduced GO (RGO)-based biosensors. ESCA survey spectra showed oxygen-containing functional groups of GO decreased from 47% to 5.7%, 4.1%, 3.8%, and 3.6% under varied reduction times of 30 min, 40 min, 50 min, and 60 min, respectively. D/G intensity ratio (ID/IG) in Raman spectra showed 1.03 after 60-min reduction process. The 60-min reduction process was further used in the electrical sensing experiments. Since different deposited layers of graphene were obtained in our experimental processes, 60-min-RGO-based biosensors have been found that those immobilized RGO possessed semiconductive property as the layers are less than 11. By contrary, when the layers were above 11, the immobilized RGO would resemble metallic material. In addition, the impedimetric analyses indicated obvious signal responses above 86 kHz and showed a concentration-dependent trend in dopamine sensing in physiological phosphate buffered saline (PBS) using 60-min-RGO-based biosensors which were feature of semiconductor.

Endogenous Biomolecules for Bioelectronic Energy Storage

The United States National Academy of Engineering has included the need to “Advance health informatics” among its 14 Grand Challenges for Engineering in the 21st Century. Bioelectronics, in concert with the Internet of Things, which seeks to enable the facile integration of implantable devices with “big data”-driven health monitoring, promises to empower personalized healthcare. For example, advances in bioelectronics have produced implantable devices for in vivo biosensing, monitoring, and therapeutics that are fabricated with biocompatible materials and seamlessly interface with biological systems and living tissue, and could therefore have enormous utility for “precision medicine”. In contrast, the field of implantable energy storage is relatively unexplored. Batteries for implantable devices currently require bulky casing because they contain toxic electrolytes and non-endogenous active materials that elicit immune responses which negatively impact device performance and long-term functionality. Therefore, development of new materials is paramount for safety and miniaturization. Ideally, implantable devices could achieve maximum biocompatibility if they exclusively comprised endogenous materials. In this context, dopamine is an electroactive, essential neurotransmitter that exhibits catechol/quinone redox functionality, and is thus an excellent candidate for implantable energy-storage. However, electronics and batteries for implantable medical devices must also resist nonspecific protein adsorption, as biofouling is the primary contributor to decreased sensitivity of implantable devices such as glucose sensors. Biological hydrogels have proven useful for masking implantable devices since they are soft, elastic, and highly permeable to low molecular weight molecules; they also effectively resist the non-specific protein adsorption that leads to cell adhesion and biofouling. To combine the electroactive properties of dopamine and the non-adhesive biocompatibility of hydrogels, we chemically conjugated hyaluronic acid (HA) and dopamine (DA) via one-step carbodiimide conjugation to form an electroactive biocomposite. Hyaluronic acid is an endogenous polysaccharide found throughout human endothelial and neural tissues, and is a primary constituent of the extracellular matrix. It has well-characterized properties, is generally non-adhesive to cells, and inhibits glial cell response. The dopamine-hyaluronic acid (DAHA) composite can be electrodeposited onto electronically conducting substrates to form an electroactive polydopamine-hyaluronic acid (p(DAHA)) biopolymer for bioelectronic energy storage. The pseudocapacitive p(DAHA) exhibits catechol-quinone interconversion, stable, long-term electroactivity for 400 cycles, and high pseudocapacitance (up to ~ 900 F g-1) and discharge capacity (~ 130 mAh g-1 at ~ 10 A g-1) in physiological phosphate-buffered saline solution. These characteristics predispose it for bioelectronic energy storage, i.e., as a supercapacitor or, when coupled with an implantable Ag/AgCl electrode, a biobattery with an operating voltage ~ 0.85 V. Figure 1

Polyelectrolyte Hydrogel Platforms for the Delivery of Antidepressant Drugs.

Some vinyl hydrogels containing α-amino acid residues (l-phenylalanine, l-valine) were used as polyelectrolyte platforms for the evaluation of the controlled release of two antidepressants (paroxetine and duloxetine). The closer acidity constant (pKa) values of the two drugs show a closer release profile in physiological phosphate buffered saline (PBS) buffer (pH 7.40) and for long periods of time. The great electrostatic interaction forces between the COO− group of the hydrogel and the protonated secondary amino nitrogen of the drug are the main factor improving the release kinetics; this release was found to be slower compared to that of two structurally related drugs bearing the tertiary amino nitrogen atom (citalopram and trazodone). Moreover, at the lower value of pH 4.60, paroxetine showed a flatter release profile from the hydrogel containing the l-phenylalanine residues that, after six days, is half of that shown by duloxetine. Further effects due to steric and hydrophobic interactions may contribute to the different release profile. A further stimulation with alternating magnetic fields (AMF) of low frequency (20 kHz/50 W) enhanced the release of the drug at pH 7.40 from the hydrogel containing magnetic nanoparticles. Both AMF and PBS solution at pH 7.40 were used to trigger the ‘on-demand’ pulsatile paroxetine release from the nanocomposite hydrogel.

Development of cephalexin-loaded poly(ethyl cyanoacrylate) colloidal nanospheres

Abstract This article considers the preparation and physicochemical characterization of a novel colloidal formulation of the β-lactam antibiotic cephalexin, loaded in poly(ethyl cyanoacrylate) colloidal nanospheres. The drug was loaded by means of drug incorporation in the interior of poly(ethyl cyanoacrylate) particles during the polymerization of the respective monomer in aqueous medium. The obtained colloids were characterized by scanning electron microscopy, dynamic and electrophoretic light scattering, Fourier transform infrared and nuclear magnetic resonance spectroscopy. It was found that the drug loading efficiency depends on the initial concentration of monomer and cephalexin in the polymerization medium. The average size of cephalexin-loaded particles was around 400 nm and did not depend significantly on the concentrations of drug and monomer. Drug-loaded particles with drug content as high as 21% (w/w) were prepared. The drug release kinetics was studied in physiological phosphate-buffered saline. It was found that a biexponential model could describe well the experimental release kinetics.

Effect of Lysimachia ramosa (Primulaceae) on helminth parasites: Motility, mortality and scanning electron microscopic observations on surface topography

The alcoholic extract of Lysimachia ramosa Wall (Primulaceae) was tested in vitro against helminth parasites, Fasciolopsis buski and Ascaris suum, from porcine hosts and Raillietina echinobothrida from domestic fowl. The live adult parasites, collected from a freshly autopsied host, were exposed to different concentrations (5–50 mg) of the test plant extract in physiological phosphate-buffered saline (PBS) having 0.1% dimethyl sulphoxide (DMSO) at 37 ± 1 °C. The treated parasites revealed complete inactivation and flaccid paralysis that was followed by death at varying periods of time. A dose-dependent loss of motility and mortality was observed in all the treated parasites. Scanning electron microscopic observations revealed conspicuous deformity of the surface architecture in all the parasites exposed to the test plant extract. The general tegument in F. buski showed shrinkage and loss of scale-like spines; proglottides all along the strobilar length in R. echinobothrida appeared shrunken and deformed and the cuticular surface of A. suum appeared disorganised, having lost transverse striations. The botanicals of the test plant seem to be effective against all the three types of helminth parasites.

Single-Wall Carbon Nanotube Nanobomb Agents for Killing Breast Cancer Cells

We report the first application of single-wall carbon nanotubes (SWCNT) as potent therapeutic nanobomb agents for killing breast cancer cells. We show here that by adsorbing water molecules in SWCNT sheets or loosely adsorbed on top of cells, potent nanobombs were created that heated the water molecules inside them to more than 100°C upon exposure to laser light of 800 nm at light intensities of approx 50–200 mW/cm2. Conversion of optical energy into thermal energy, and the subsequent confinement of thermal energy in SWCNT, caused the water molecules to evaporate and develop extreme pressures in SWCNT causing them to explode in solutions. Co-localized nanobombs killed human BT474 breast cancer cells in physiological phosphate-buffered saline (PBS) solution. Cells that were treated with nanobombs exploded into fragments, while the surrounding cells not treated with nanobombs were viable. SWCNT-based nanobomb agents can potentially outperform most nanotechnological approaches in killing cancer cells without toxicity.

Development of agents for reinforcement of fluorescence on near-infrared ray excitation for immunohistological staining

Fluorescence intensity of indocyanine green (ICG) derivative (ICG-sulfo-OSu) was too low for its use to detect microlesions. Therefore, we examined the effects of reinforcement agents on ICG-sulfo-OSu labeled antibodies. Solutions of distearoylphosphatic acid sodium salt (DSPA) and octylglucoside (OG) in physiological phosphate buffered saline (PBS) were found to increase the intensity of fluorescence of ICG-sulfo-OSu labeled antibodies, with shift in the fluorescence peak wavelength from 804 to 821 nm.

Effect of hyaluronan on the healing of partially ruptured anterior cruciate ligament of rabbits

The midportion of the anterior cruciate ligament (ACL) of rabbits was partially transected, and the effect of hyaluronan (HA) on its healing was determined. A 1% solution of HA (HA group) or physiological phosphate-buffered saline (control group) was administered intraarticularly, at 0.1ml/kg body weight, once a week from 1 week after the operation. Two, 4, and 6 weeks after the initiation of HA administration, the ACLs were examined grossly, histologically and immunohistochemically. At 2 weeks, the lacerated portions were completely covered with scar-like tissue in both groups. These tissue areas were smaller in the HA group than in the control group. Histologically in the HA group, the regularity of collagen fibers (indicating the maturity of regenerated collagen fibers) had increased compared to findings in the control group, and the number of fibroblastic cells decreased gradually at a significantly faster rate. The number of inflammatory cells and blood vessels decreased gradually in both groups, with these values being lower in the HA group at each time point but not significantly so. Immunohistochemical examination of the repaired tissue revealed strong staining with anti-chondroitin sulfate proteoglycan antibody in the HA group 2 weeks after the first HA administration. The staining gradually became reduced, with the rate of reduction being faster in the HA group than in the control group. The stimulation of chondroitin sulfate proteoglycan production and the faster reduction of it in the HA group suggests that HA facilitated tissue repair and inhibited the formation of scar tissue.

Injury of Escherichia coli in physiological phosphatebuffered saline induced by far-infrared irradiation.

Injury in Escherichia coli irradiated by far-infrared radiation (FIR) was examined. We used penicillin G (PCG), chloramphenicol (CP), rifampicin (RFP) and nalidixic acid (NA) as selective reagents, and tried to evaluate the injury in bacteria irradiated by FIR on the basis of the changes in the sensitivity to selective reagents. The validity of this method was examined using UV pasteurization. E. coli irradiated by UV became more sensitive to CP and NA, which indicated that UV irradiation damaged nueleic acid in E. coli. This result agrees with those demonstrated by many researchers and suggests this method is applicable to useful evaluation of the damaged part in bacteria induced by stresses. E. coli irradiated by FIR became more sensitive to RFP and CP, which suggests that FIR irradiation damages RNA polymerase and ribosome in E. coli. Though similar changes in the sensitivity were obtained in the case of thermal conductive heating, the pasteurization effect of FIR irradiation was much greater than that of conductive heating.

Cellular DNA damage by hydrogen peroxide is attenuated by hypotonicity.

Chinese hamster fibroblasts (line V79) withstand well exposure for 30 min to hypotonic medium, corresponding to 25% physiological phosphate-buffered saline (PBS). Under these conditions, the cells become resistant to two effects of H2O2: DNA damage and inhibition of cell clone formation. The normal sensitivity to the DNA-damaging action of H2O2 is restored if, after exposure to hypotonic PBS, the cells are incubated in isotonic cell-culture medium. However, restoration of sensitivity is not observed on incubation in isotonic PBS. The normal sensitivity to H2O2 is also restored if one of the following reducing agents is added to hypotonic PBS: ascorbate, NADH and NADPH, in this order of decreasing efficiency. The recovery of sensitivity to H2O2 by ascorbate is completely inhibited by 1,10-phenanthroline, indicating that ascorbate is mediating the reduction of Fe(III). The decrease in the sensitivity to the DNA-damaging action of H2O2 is not a peculiarity of hypotonic PBS, since it appears to be caused by hypo-osmolarity in general: it is also observed in culture medium of 25% the isotonic concentration, and in 0.07 M sucrose. One explanation for this phenomenon is that hypotonic stress leads to a depletion of reducing species, in particular ascorbate. Under these conditions Fe(II) tends to be oxidized to Fe(III) and the Fenton chemistry is mitigated. However, other possibilities are that hypotonicity brings about structural modifications in the chromatin, rendering it less accessible to H2O2, or that it attenuates the Ca(2+)-activation of endonuclease, induced by oxidative stress.

Further characterization of the effects of alpha-1-acid glycoprotein on the passage of human erythrocytes through micropores.

Effects of human alpha-1-acid glycoprotein (AG) on the passage of human red blood cell(s) (RBC) through membrane filters with micropores were examined in vitro. RBCs, with a mean major diameter of 7.2 micron, that had been suspended at 1% in physiological phosphate-buffered saline (PBS), were filtered through membrane filters of various pore diameters under positive pressure. The percentages of cells that passed through the micropores and of cells hemolyzed during filtration were determined. RBCs suspended in PBS did not pass through micropores that had an average pore diameter of 3 micron; instead hemolysis took place. Neither temperature nor applied pressure affected cell passage; but when AG at 0.1 mg/ml or above was added to an RBC-suspension, it promoted cell passage through the 3 micron micropores and reduced the degree of hemolysis. The effects of AG were dose dependent up to a concentration of 0.5 mg/ml. The addition of AG to an RBC-suspension that contained 90% human serum had the same additive effects. Washing AG-treated RBCs with normal saline produced a marked decrease in cell passage through the 3 micron pores. Fluorescence antibody staining revealed that the exogenous AG was localized on the membrane surface of the RBCs. Our results suggest that the AG bound to the surface of the RBCs acts as a lubricant between the RBCs and the wall of the micropore; this would facilitate RBC-passage through the micropores.