Poly(lactic acid) crystallization

Rising environmental concerns and depletion of petro-chemical resources has resulted in an increased interest in biorenewable polymer-based environmentally friendly materials. Among biorenewable polymers, lignin is the second most abundant and fascinating natural polymer next to cellulose. Lignin is one of the three major components found in the cell walls of natural lignocellulosic materials. Lignin is widely available as a major byproduct of a number of industries involved in retrieving the polysaccharide components of plants for industrial applications, such as in paper making, ethanol production from biomass, etc. The impressive properties of lignin, such as its high abundance, low weight, environmentally friendliness and its antioxidant, antimicrobial, and biodegradable nature, along with its CO2 neutrality and reinforcing capability, make it an ideal candidate for the development of novel polymer composite materials. Considerable efforts are now being made to effectively utilize waste lignin as one ...

Progress in Green Polymer Composites from Lignin for Multifunctional Applications: A Review

This literature review is a compilation of the composition and, in most cases, the preparation instructions for simulated biological fluids that may be used as dissolution media in the evaluation of dissolution profiles and amount of drug released from pharmaceutical dosage forms. The use of simulated biological fluids can give a better understanding of the release mechanisms and possible in vivo behavior of a product and enhance the predictive capability of the dissolution testing. A summary of the major characteristics of the most used routes of administration that may affect dissolution and absorption of drug substances is presented. The routes and simulated biological fluids covered by this review are: • Parenteral: simulated body fluid and simulated synovial fluid. • Oral: fasted-state simulated gastric fluid, fed-state simulated gastric fluid, fasted-state simulated intestinal fluid, fed-state simulated intestinal fluid, simulated colonic fluid, fasted-state simulated colonic fluid, and fed-state simulated colonic fluid. • Buccal and sublingual: simulated saliva. • Pulmonary: simulated lung fluid. • Vaginal: simulated vaginal fluid and simulated semen. • Ophthalmic: simulated tears. Simulated sweat is also included. Some examples of how these simulated biological fluids are used to evaluate dosage forms are included in each route of administration. INTRODUCTION Until some decades ago, most of the conventional pharmaceutical dosage forms were essentially injections, oral formulations (solutions, suspensions, tablets, and capsules), topical creams, and ointments. With the progress of drug delivery technology, novel dosage forms have been developed to overcome the problems associated with conventional drug delivery. Research has been directed toward the use of alternatives to the parenteral route for drugs that cannot be delivered orally. Potential alternative portals of drug entry to the systemic circulation include buccal, sublingual, nasal, pulmonary, and vaginal routes, among others. These routes of administration are also used for the local delivery of drugs directly to the site of action, with consequent reduction in the dose needed to produce a pharmacological effect, eliminating problems related to first-pass metabolism and possibly minimizing systemic side effects (1). An important application of dissolution testing is the prediction of in vivo performance of pharmaceutical dosage forms. The media typically used for quality control dissolution testing do not represent all aspects of the physiological conditions of the most used routes of administration and do not allow correlation with in vivo data. Prediction of dosage form performance in the site where most of the absorption occurs requires adequate simulation of the in vivo conditions. This paper describes some characteristics of the parenteral, oral, buccal and sublingual, pulmonary, ophthalmic, and vaginal routes that are important to consider when developing simulated media. A compilation of the composition and preparation of several simulated biological fluids, including simulated sweat, with potential use as dissolution media is presented. PARENTERAL ROUTE The most used routes of injection are intramuscular, intravenous, and subcutaneous and are normally associated with short-term effects. Novel implant devices that can adequately control drug release and provide a prolonged duration of effect have been developed (1). To evaluate the in vitro drug release from these dosage forms, the dissolution medium should have ion concentrations almost equal to those of the human plasma. Table 1 describes the ionic composition of simulated body fluid (SBF) and human blood plasma. Simulated body fluid was developed initially to evaluate the surface structural changes of glass-ceramics used to manufacture artificial vertebrae, ileum, tooth roots (2), and bioactive material used to repair hard tissues such as artificial middle-ear bone and maxillofacial implants (3). This simulated body fluid was prepared using the reagents listed in Table 2. These reagents were added to 700 mL of water in the order given in Table 2, one by one, after each reagent was completely dissolved. The pH was adjusted to 7.4 with 1 M *Corresponding author. diss-18-03-03.indd 15 8/31/2011 3:22:15 PM dx.doi.org/10.14227/DT180311P15

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Simulated Biological Fluids with Possible Application in Dissolution Testing

We investigated the effects of inhibitors of clathrin-mediated endocytosis (chlorpromazine and K(+) depletion) and of caveolae-mediated uptake (filipin and genistein) on internalization of FITC-poly-l-lysine-labeled DOTAP/DNA lipoplexes and PEI/DNA polyplexes by A549 pneumocytes and HeLa cells and on the transfection efficiencies of these complexes with the luciferase gene. Uptake of the complexes was assayed by fluorescence-activated cell sorting. Lipoplex internalization was inhibited by chlorpromazine and K(+) depletion but unaffected by filipin and genistein. In contrast, polyplex internalization was inhibited by all four inhibitors. We conclude that lipoplex uptake proceeds only by clathrin-mediated endocytosis, while polyplexes are taken up by two mechanisms, one involving caveolae and the other clathrin-coated pits. Transfection by lipoplexes was entirely abolished by blocking clathrin-mediated endocytosis, whereas inhibition of the caveolae pathway had no effect. By contrast, transfection mediated by polyplexes was completely blocked by genistein and filipin but was unaffected by inhibitors of clathrin-mediated endocytosis. Fluorescence colocalization studies with a lysosomal marker, AlexaFluor-dextran, revealed that polyplexes taken up by clathrin-mediated endocytosis are targeted to the lysosomal compartment for degradation, while the polyplexes internalized via caveolae escape this compartment, permitting efficient transfection.

Role of clathrin- and caveolae-mediated endocytosis in gene transfer mediated by lipo- and polyplexes

Thermal processing of starch-based polymers

Drug delivery systems (DDSs) are designed to be able to precisely control the release rate and/or target drugs to specific body sites. However, the successful application of DDSs could be limited in the clinical application due to the complicated environment of the human body. This can be exampled by the short circulation time and low targeting efficiency of target-specific DDSs induced by the RES recognition, or low bioavailability of drugs caused by short residence time of transmucosal DDSs at the site of absorption. Regarding this, in this chapter, strategies to improve the performance and bioavailability of starch-based DDSs are discussed. Target-specific starch-based DDSs can be achieved by passive and active targeting. Another possible strategy is the physical targeting of drugs by external stimuli, such as magnetic field. Also, the role of starch and its derivatives in transmucosal DDSs to improve the bioavailability of drugs by interacting with the absorbing mucosa or prolonging the residence time of drugs in the absorbing tissues are highlighted.

Starch-Based DDSs with Physiological Interactions

To improve insufficient taste and imbalanced aroma of enzyme-modified cheese (EMC), pre-enzymolysis followed by lactic acid bacteria (LAB) fermentation was employed in this study. The strategy generated taste compounds by fermentation and released crucial flavor precursors by pre-enzymolysis. Flavor precursors and flavor compounds from each step were measured. Results showed that 45–50 and 15–17 times higher free amino acid (FAA) and free fatty acid (FFA) flavor precursors than the control were respectively achieved based on acceptable bitterness and soapiness during pre-enzymolysis. Pre-proteolysis accelerated fermentation and increased lactic acid, floral and almond aromatic ring compounds from phenylalanine (2.0–15.7 times), and rancid branched acids from leucine (3.2–4.4 times) during fermentation. Pre-lipolysis released massive methyl ketones and fatty acids, but flavor imbalanced, which was improved by promoting short-chain fatty acid production during fermentation. These results provided practical references for producing EMC with authentic Cheddar flavor and new avenues for flavor improvement of EMC. 

Flavor precursors and flavor compounds in Cheddar-flavored enzyme-modified cheese due to pre-enzymolysis combined with lactic acid bacteria fermentation

As drugs are not inherently effective, the benefits of their treatment are closely related to the performance of drug delivery carriers. Given this, the interactions and stimulus responsiveness of the carrier materials within the human body play an important role in the performance of smart drug delivery systems (DDSs). Stimulated by advances in polymer materials, the stimulus responsiveness of drug carriers can be achieved by incorporating “to be triggered” constituting units or compositions within their own structure to acquire specific physicochemical properties. Thus, drugs can be released under specific stimuli resulting from the chemical degradation and physical conformation change of carriers. Another way to achieve stimulus responsiveness is to take advantage of drug–carrier interactions, whether they are chemical bonds or physical interactions. Once these drug–carrier interactions are broken or weakened, the drug will be released with responsiveness. On the other hand, the drug delivery efficiency of DDSs, especially target specificity, can be modulated by the physicochemical properties of carriers (e.g., hydrophobicity/hydrophilicity, size, shape, and surface charge) directing their interactions with tissues, cells, and biomacromolecules. By choosing appropriate materials of carriers and adjusting their structure and physicochemical properties, the well-controlled drug delivery and release of the therapeutics from carriers can be realized.

Material Nature and Physicochemical Properties for High Performance of Carriers

[This corrects the article DOI: 10.3389/fmicb.2020.615875.].

Corrigendum: First report on the rapid detection and identification of methicillin-resistant Staphylococcus aureus (MRSA) in viable but non-culturable (VBNC) under food storage conditions

A new consolidation in-situ forming process for high-performance alumina ceramic using acetate starch was investigated. The pasting behavior and thermogelling properties of acetate starch and the effects of different amount of acetate starch and solid loading on the rheologic behavior of the ceramic slip, as well as the linear shrinkage, density, strength and microstructure of the green body were discussed. The results indicate that acetate starch paste has good thermal stability and gelling ability. When the content of acetate starch is about 0.5%~1.5% (mass fraction), the apparent viscosity of alumina slurry, which is always less than 1Pa·s even for 58% (volume fraction) dense suspension, increased with increasing the acetate starch content and solid loading. That results in easier to cast. Moreover, with the increasing of solid loading the linear shrinkage and dry strength of green bodies decreased and the relative density increased. With the increasing starch content, the linear shrinkage rate and the density of the dried body decreased, while the strength of the dried body almost linearly increased. The green body with homogeneously-distributed density and pore size was also obtained in this work. It is concluded that Al2O3 ceramics can be consolidation in-situ formed based on the gelling network of thermally swelled and gelatinized acetate starch.

Ling Chen

Papers

Starch-Based DDSs with Physiological Interactions

Flavor precursors and flavor compounds in Cheddar-flavored enzyme-modified cheese due to pre-enzymolysis combined with lactic acid bacteria fermentation

Material Nature and Physicochemical Properties for High Performance of Carriers

Corrigendum: First report on the rapid detection and identification of methicillin-resistant Staphylococcus aureus (MRSA) in viable but non-culturable (VBNC) under food storage conditions

Application of Acetate Starch to Colloidal In Situ Consolidation Molding Process of Alumina Ceramic