Lidocaine loaded biodegradable nanospheres. II. Modelling of drug release

The Synthesis, Characterization and Applications of Polyhydroxyalkanoates (PHAs) and PHA-Based Nanoparticles

Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.

Uptake and Release Kinetics of Organic Contaminants Associated with Micro- and Nanoplastic Particles

A generic theoretical framework is presented for describing the kinetics of uptake and release of organic compounds that associate with plastic particles. The underlying concepts account for the physicochemical features of the target organic compounds and the plastic particles. The developed framework builds on concepts established for dynamic speciation analysis by solid-phase microextraction and the size-dependent reactivity features of particulate complexants. The theoretical framework is applied to interpretation of literature data, thereby providing more rigorous insights into previous observations. The presented concepts enable predictions of the sink/source functioning of plastic particles and their impact on the dynamic chemical speciation of organic compounds in aqueous environmental media and within biota. Our results highlight the fundamental influence of particle size on the uptake and release kinetics. The findings call for a comprehensive description of the physicochemical features of plastic particles to be provided in experimental studies on micro- and nanoplastics in different types of aquatic environmental media.

Nanomaterials for removal of waterborne pathogens

As the nanotechnological applications have taken over in different fields, their applications for water and wastewater treatment is also surfacing as a fast-developing and very promising area. Recent advancements in nanotechnological science and engineering advise that many of the waterborne pathogens could be culminated or debilitated using nanobiosorbents, nanocatalysts, bioactive nanoparticles, nanostructured catalytic membranes, nanobioreactors, nanoparticle-enhanced filtration among other products, and processes resulting from the development of nanotechnology. A detailed insight has been provided for advanced techniques such as photochemical (photocatalytic and advanced oxidation processes) applications of metal oxide nanoparticles, nanomembrane technology, bioinspired nanomaterials, and nanotechnological innovations (nano-Ag, fullerenes, nanotubes, and molecularly imprinted polymers, etc.), which prove to be highly potential as well as promising and cost-effective. However, there are still some shortcomings and challenges that must be overcome which will be looked upon in this chapter.

Interfacial interaction of anesthetic lidocaine and mesoporous silica nanoparticles in aqueous solutions and its release properties

Lidocaine has been used as a local anesthetic by injection. The controlled release of lidocaine loaded into nanospheres is necessary to reduce the onset time of the anesthetic effect or increase the anesthetic analgesia duration. In this study, mesoporous silica nanoparticles (MSNs) with a large specific surface area were prepared by a sol-gel method, and the interfacial interaction between MSNs and lidocaine positively charged in aqueous solutions at different concentrations was investigated by adsorption tests, Fourier-transformed infrared spectroscopy, thermogravimetry-differential thermal analysis, and Brunauer-Emmett-Teller (BET) measurements. The electrostatic interaction between Si-OH on MSNs and lidocaine-NH⁺ was of importance for the adsorption phenomenon in aqueous solutions, indicating the monolayer adsorption of lidocaine. BET measurements also supported the decrease of pore volumes, and the hysteresis loop of the isotherm curve was not closed since the condensation of lidocaine in the mesopores formed micropores of less than 1.5 nm in size. The release profiles in phosphate buffered saline containing calcium and magnesium ions showed a rapid and higher release of lidocaine compared with that in phosphate buffered saline without divalent cations. The released lidocaine concentrations were sufficient for the expression of the anesthetic effect in dental anesthesia.

Loading-Dependent Structural Model of Polymeric Micelles Encapsulating Curcumin by Solid-State NMR Spectroscopy

Detailed insight into the internal structure of drug‐loaded polymeric micelles is scarce, but important for developing optimized delivery systems. We observed that an increase in the curcumin loading of triblock copolymers based on poly(2‐oxazolines) and poly(2‐oxazines) results in poorer dissolution properties. Using solid‐state NMR spectroscopy and complementary tools we propose a loading‐dependent structural model on the molecular level that provides an explanation for these pronounced differences. Changes in the chemical shifts and cross‐peaks in 2D NMR experiments give evidence for the involvement of the hydrophobic polymer block in the curcumin coordination at low loadings, while at higher loadings an increase in the interaction with the hydrophilic polymer blocks is observed. The involvement of the hydrophilic compartment may be critical for ultrahigh‐loaded polymer micelles and can help to rationalize specific polymer modifications to improve the performance of similar drug delivery systems.

Delivering amoxicillin at the infection site - a rational design through lipid nanoparticles

Purpose

Amoxicillin is a commonly used antibiotic, although degraded by the acidic pH of the stomach. This is an important limitation for the treatment of Helicobacter pylori infections. The purpose of this work was to encapsulate amoxicillin in lipid nanoparticles, increasing the retention time at the site of infection (gastric mucosa), while protecting the drug from the harsh conditions of the stomach lumen.

Materials and methods

The nanoparticles were produced by the double emulsion technique and optimized by a three-level Box-Behnken design. Tween 80 and linolenic acid were used as potential therapeutic adjuvants and dioleoylphosphatidylethanolamine as a targeting agent to Helicobacter pylori. Nanoparticles were characterized regarding their physico-chemical features, their storage stability, and their usability for oral administration (assessment of in vitro release, in vitro cell viability, permeability, and interaction with mucins).

Results

The nanoparticles were stable for at least 6 months at 4°C. In vitro release studies revealed a high resistance to harsh conditions, including acidic pH and physiologic temperature. The nanoparticles have a low cytotoxicity effect in both fibroblasts and gastric cell lines, and they have the potential to be retained at the gastric mucosa.

Conclusion

Overall, the designed formulations present suitable physico-chemical features for being henceforward used by oral administration to treat Helicobacter pylori infections.

Drug delivery systems for programmed and on-demand release

With the advancement in medical science and understanding the importance of biodistribution and pharmacokinetics of therapeutic agents, modern drug delivery research strives to utilize novel materials and fabrication technologies for the preparation of robust drug delivery systems to combat acute and chronic diseases. Compared to traditional drug carriers, which could only control the release of the agents in a monotonic manner, the new drug carriers are able to provide a precise control over the release time and the quantity of drug introduced into the patient's body. To achieve this goal, scientists have introduced "programmed" and "on-demand" approaches. The former provides delivery systems with a sophisticated architecture to precisely tune the release rate for a definite time period, while the latter includes systems directly controlled by an operator/practitioner, perhaps with a remote device triggering/affecting the implanted or injected drug carrier. Ideally, such devices can determine flexible release pattern and intensify the efficacy of a therapy via controlling time, duration, dosage, and location of drug release in a predictable, repeatable, and reliable manner. This review sheds light on the past and current techniques available for fabricating and remotely controlling drug delivery systems and addresses the application of new technologies (e.g. 3D printing) in this field.

Building the design, translation and development principles of polymeric nanomedicines using the case of clinically advanced poly(lactide(glycolide))-poly(ethylene glycol) nanotechnology as a model: An industrial viewpoint

The design of the first polymeric nanoparticles could be traced back to the 1970s, and has thereafter received considerable attention, as evidenced by the significant increase of the number of articles and patents in this area. This review article is an attempt to take advantage of the existing literature on the clinically tested and commercialized biodegradable PLA(G)A-PEG nanotechnology as a model to propose quality building and outline translation and development principles for polymeric nano-medicines. We built such an approach from various building blocks including material design, nano-assembly - i.e. physicochemistry of drug/nano-object association in the pharmaceutical process, and release in relevant biological environment - characterization and identification of the quality attributes related to the biopharmaceutical properties. More specifically, as envisaged in a translational approach, the reported data on PLA(G)A-PEG nanotechnology have been structured into packages to evidence the links between the structure, physicochemical properties, and the in vitro and in vivo performances of the nanoparticles. The integration of these bodies of knowledge to build the CMC (Chemistry Manufacturing and Controls) quality management strategy and finally support the translation to proof of concept in human, and anticipation of the industrialization takes into account the specific requirements and biopharmaceutical features attached to the administration route. From this approach, some gaps are identified for the industrial development of such nanotechnology-based products, and the expected improvements are discussed. The viewpoint provided in this article is expected to shed light on design, translation and pharmaceutical development to realize their full potential for future clinical applications.

Encapsulation of Biological and Chemical Agents for Plant Nutrition and Protection: Chitosan/Alginate Microcapsules Loaded with Copper Cations and Trichoderma viride

Novel chitosan/alginate microcapsules simultaneously loaded with copper cations and Trichoderma viride have been prepared and characterized. Information about the intermolecular interactions between biopolymers and bioactive agents was obtained by Fourier transform infrared spectroscopy. Encapsulation of T. viride spores and the presence of copper cations in the same compartment does not inhibit their activity. Microcapsule loading capacity and efficiency as well as swelling behavior and release depend on both the size of the microcapsule and bioactive agents. The in vitro copper cation release profile was fitted to a Korsmeyer-Peppas empirical model. Fickian diffusion was found to be a rate-controlling mechanism of release from smaller microcapsules, whereas anomalous transport kinetics controlled release from larger microcapsules. The T. viride spore release profile exhibited exponential release over the initial lag time. The results obtained opened perspectives for the future use of chitosan/alginate microcapsules simultaneously loaded with biological and chemical agents in plant nutrition and protection.

Heparin-appended polycaprolactone core/corona nanoparticles for site specific delivery of 5-fluorouracil

The aim of the present work is to formulate heparin-modified-polycaprolactone (HEP) core shell nanoparticles (NPs) of 5-fluorouracil (5-FU). These NPs were characterized for various in vitro parameters like particle size, zeta potential, etc. HEP NPs were found to maintain comparatively slower drug release pattern (98.9% in 96 h) than PCL NPs. Cytotoxicity studies demonstrated a massive cytotoxic potential of 5-FU-loaded HEP NPs in A549, MDA-MD-435, and SK-OV-3 cancer cell lines. Pharmacokinetic parameters were also determined in blood after IV administration of HEP NPs: AUC, C_max, MRT, and T_max values are 6096.075 ± 5.90 μg h/mL, 144.38 ± 1.52 μg/L, 58.71 ± 0.25 h, 96 ± 0.50 h, respectively and 117.92 ± 1.78, 45.35 ± 3.00, 1.2 ± 0.25, 0.5 ± 0.02 in plain 5-FU solution.

From micro- to nanostructured implantable device for local anesthetic delivery

Local anesthetics block the transmission of painful stimuli to the brain by acting on ion channels of nociceptor fibers, and find application in the management of acute and chronic pain. Despite the key role they play in modern medicine, their cardio and neurotoxicity (together with their short half-life) stress the need for developing implantable devices for tailored local drug release, with the aim of counterbalancing their side effects and prolonging their pharmacological activity. This review discusses the evolution of the physical forms of local anesthetic delivery systems during the past decades. Depending on the use of different biocompatible materials (degradable polyesters, thermosensitive hydrogels, and liposomes and hydrogels from natural polymers) and manufacturing processes, these systems can be classified as films or micro- or nanostructured devices. We analyze and summarize the production techniques according to this classification, focusing on their relative advantages and disadvantages. The most relevant trend reported in this work highlights the effort of moving from microstructured to nanostructured systems, with the aim of reaching a scale comparable to the biological environment. Improved intracellular penetration compared to microstructured systems, indeed, provides specific drug absorption into the targeted tissue and can lead to an enhancement of its bioavailability and retention time. Nanostructured systems are realized by the modification of existing manufacturing processes (interfacial deposition and nanoprecipitation for degradable polyester particles and high- or low-temperature homogenization for liposomes) or development of novel strategies (electrospun matrices and nanogels). The high surface-to-volume ratio that characterizes nanostructured devices often leads to a burst drug release. This drawback needs to be addressed to fully exploit the advantage of the interaction between the target tissues and the drug: possible strategies could involve specific binding between the drug and the material chosen for the device, and a multiscale approach to reach a tailored, prolonged drug release.

Long-term effect of ropivacaine nanoparticles for sciatic nerve block on postoperative pain in rats

Purpose

The analgesic effect of ropivacaine (Rop) for nerve block lasts only ~3–6 hours for single use. The aim of this study was to develop long-acting regional anesthetic Rop nanoparticles and investigate the effects of sciatic nerve block on postoperative pain in rats.

Materials and methods

Rop nanoparticles were developed using polyethylene glycol-co-polylactic acid (PELA). One hundred and twenty adult male Wistar rats were randomly divided into four groups (n=30, each): Con (control group; 0.9% saline, 200 µL), PELA (PELA group; 10 mg), Rop (Rop group; 0.5%, 200 µL), and Rop-PELA (Rop-PELA group; 10%, 10 mg). Another 12 rats were used for the detection of Rop concentration in plasma. The mechanical withdrawal threshold and thermal withdrawal latency were measured at 2 hours, 4 hours, 8 hours, 1 day, 2 days, 3 days, 5 days, and 7 days after incision. The expression of c-FOS was determined by immunohistochemistry at 2 hours, 8 hours, 48 hours, and 7 days. Nerve and organ toxicities were also evaluated at 7 days.

Results

The duration of Rop absorption in the plasma of the Rop-PELA group was longer (>8 hours) than that of the Rop group (4 hours). Mechanical withdrawal threshold and thermal withdrawal latency in the Rop-PELA group were higher than that in other groups (4 hours–3 days). c-FOS expression in the Rop-PELA group was lower than that in the control group at 2 hours, 8 hours, and 48 hours and lower than that in the Rop group at 8 hours and 48 hours after paw incision. Slight foreign body reactions were observed surrounding the sciatic nerve at 7 days. No obvious pathophysiological change was found in the major organs after Rop-PELA administration at 7 days.

Conclusion

Rop-PELA provides an effective analgesia for nerve block over 3 days after single administration, and the analgesic mechanism might be mediated by the regulation of spinal c-FOS expression. However, its potential long-term tissue toxicity needs to be further investigated.

Sustained relief of pain from osteosynthesis surgery of rib fracture by using biodegradable lidocaine-eluting nanofibrous membranes

Various effective methods are available for perioperative pain control in osteosynthesis surgery, but they are seldom applied intraoperatively. The aim of this study was to evaluate a biodegradable poly([d,l]-lactide-co-glycolide) (PLGA)/lidocaine nanofibrous membrane for perioperative pain control in rib fracture surgery. Scanning electron microscopy showed high porosity of the membrane, and an ex vivo high-performance liquid chromatography study revealed an excellent release profile for both burst and controlled release of lidocaine within 30days. Additionally, the PLGA/lidocaine nanofibrous membrane was applied in an experimental rabbit rib osteotomy model. Implantation of the membrane around the osteotomized rib during osteosynthesis surgery resulted in a significant increase in weight gain, food and water consumption, and daily activity compared to the study group without the membrane. In addition, all osteotomized ribs were united. Thus, application of the PLGA/lidocaine nanofibrous membrane may be effective for sustained relief of pain in oeteosynthesis surgery.

Polymer degradation and drug delivery in PLGA-based drug-polymer applications: A review of experiments and theories

Poly (lactic-co-glycolic acid) (PLGA) copolymers have been broadly used in controlled drug release applications. Because these polymers are biodegradable, they provide an attractive option for drug delivery vehicles. There are a variety of material, processing, and physiological factors that impact the degradation rates of PLGA polymers and concurrent drug release kinetics. This work is intended to provide a comprehensive and collective review of the physicochemical and physiological factors that dictate the degradation behavior of PLGA polymers and drug release from contemporary PLGA-based drug-polymer products. In conjunction with the existing experimental results, analytical and numerical theories developed to predict drug release from PLGA-based polymers are summarized and correlated with the experimental observations. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1692-1716, 2017.

Polymeric and Solid Lipid Nanoparticles for Sustained Release of Carbendazim and Tebuconazole in Agricultural Applications

Carbendazim (MBC) (methyl-2-benzimidazole carbamate) and tebuconazole (TBZ) ((RS)-1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol) are widely used in agriculture for the prevention and control of fungal diseases. Solid lipid nanoparticles and polymeric nanocapsules are carrier systems that offer advantages including changes in the release profiles of bioactive compounds and their transfer to the site of action, reduced losses due to leaching or degradation, and decreased toxicity in the environment and humans. The objective of this study was to prepare these two types of nanoparticle as carrier systems for a combination of TBZ and MBC, and then investigate the release profiles of the fungicides as well as the stabilities and cytotoxicities of the formulations. Both nanoparticle systems presented high association efficiency (>99%), indicating good interaction between the fungicides and the nanoparticles. The release profiles of MBC and TBZ were modified when the compounds were loaded in the nanoparticles, and cytotoxicity assays showed that encapsulation of the fungicides decreased their toxicity. These fungicide systems offer new options for the treatment and prevention of fungal diseases in plants.

Physicochemical studies on local anaesthetic loaded second generation nanolipid carriers

Effect of drug concentration on different properties of NLC.

Formulation and characterization of clozapine and risperidone co-entrapped spray-dried PLGA nanoparticles

In the current study, polylactide-co-glycolide (PLGA) nanoparticles entrapping both clozapine (CLZ) and risperidone (RIS) were formulated by spray-drying using Buchi Nano Spray Dryer B-90 (Flawil, Switzerland). Parameters such as inlet temperature, spray mesh diameter, sample flow rate, spray rate and applied pressure were optimized to produce nanoparticles having desired release profile using both low- and high-molecular weight PLGA polymer. Smallest size nanoparticle of size around 248 nm could be prepared using a 4.0 μm mesh diameter with low-molecular weight polymer. The load of CLZ and RIS was 126.3 and 58.2 μg/mg of polymer particles, respectively. Entrapment efficiency of drugs in PLGA nanoparticles was 94.74% for CLZ and 93.12% for RIS. Both the drugs released continuously from the nanoparticle formulations. PLGA nanoparticles formulated using low-molecular weight polymer released around 80% of the entrapped drug over 10 days of time. Nature of drug inside polymer particles was amorphous, and there was no chemical interaction of CLZ and RIS with polymer. Polymeric nanoparticles were found to be non-toxic in nature using PC12 cell line. This nanospray drying process proved to be suitable for developing polymeric nanoformulation delivering dual drugs for the treatment of Schizophrenia.

SYNTHESIS AND CHARACTERIZATION OF POLYSIALIC ACID-N-TRIMETHYL CHITOSAN NANOPARTICLES FOR DRUG DELIVERY

In drug delivery, the nanoparticles must be of proper size and charge to achieve high efficacy and low toxicity of associated therapeutics. In this study, nanoparticles were developed via ionic gelation of two polysaccharide-based molecules, negatively charged polysialic acid (PSA) and positively charged N,N,N-trimethylchitosan (TMC). PSA is unique in that the highly hydrated backbone may be used in a manner similar to that of poly(ethylene glycol) to extend circulation times. Although not necessary for nanoparticle formation, sodium tripolyphosphate (TPP) was added to enhance stability, as indicated by a reduced polydispersity. We investigated three different ratios by weight of PSA:TMC (0.5:1, 1:1, 1:2 and five different TPP concentrations ranging from 0.1 mg/ml to 0.8 mg/ml. As controls, nanoparticles were also formed without PSA from chitosan and TMC with TPP. Optimal size and surface charge were achieved with a PSA:TMC weight ratio of 0.5:1 and a TPP concentration 0.2 mg/ml. For the nanoparticles prepared in the latter fashion, a more in depth characterization was conducted. The nanoparticles were distinct solid, spherical nanogels with a size of 106 ± 25 nm, an ideal size to reduce uptake by the reticuloendothelial system while facilitating passive targeting of diseased tissue. The zeta potential of the nanoparticles was +33.9 ± 1.2 mV, suggesting that the nanoparticles will be stable under physiological conditions. Encapsulation and controlled release by the nanoparticles was demonstrated using methotrexate, a therapeutic indicated in both cancer and rheumatoid arthritis. The results obtained thus far strongly indicate that PSA–TMC nanoparticles are suitable drug carrier systems for systemic administration.

Colloidal stability of polymeric nanoparticles in biological fluids

Estimating the colloidal stability of polymeric nanoparticles (NPs) in biological environments is critical for designing optimal preparations and to clarify the fate of these devices after administration. To characterize and quantify the physical stability of nanodevices suitable for biomedical applications, spherical NPs composed of poly-lactic acid (PLA) and poly-methyl-methacrylate (PMMA), in the range 100-200 nm, were prepared. Their stability in salt solutions, biological fluids, serum and tissue homogenates was analyzed by dynamic light scattering (DLS). The PMMA NPs remained stable in all fluids, while PLA NPs aggregated in gastric juice and spleen homogenate. The proposed stability test is therefore useful to see in advance whether NPs might aggregate when administered in vivo. To assess colloidal stability ex vivo as well, spectrophotofluorimetric analysis was employed, giving comparable results to DLS.