Freeze-Drying of Low Molecular Weight Poly(L-lactic acid) Nanoparticles: Effect of Cryo- and Lyoprotectants

2006 ◽  
Vol 6 (9) ◽  
pp. 3110-3117 ◽  
Author(s):  
Samuli Hirsjärvi ◽  
Leena Peltonen ◽  
Laura Kainu ◽  
Jouni Hirvonen
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Polymeric Nanoparticles ◽  
Physical Stability ◽  
Tween 80 ◽  
Particle Dispersion ◽  
Low Molecular Weight ◽  
Freeze Dried ◽  
Original Size ◽  
The Stability

The chemical and physical stability of polymeric nanoparticles is poor in aqueous suspensions, and the drying of these particles is often problematic. In the present study, the stability of freeze-dried low molecular weight poly(L-lactic acid) (PLA) nanoparticles was enhanced by adding glucose and/or lactose to the formulation as cryo- and lyoprotectants, respectively. Also the effect of an extra stabilizer, Tween 80, was studied. The best freeze-dried PLA nanoparticle formulations were achieved, when glucose and lactose were added in combination so that the amount of lactose was double the amount of glucose. With this combination the redispersion of high-quality nanoparticles (homogenous particle dispersion with original size and without aggregates) was achieved. The addition of Tween 80 further improved the quality of freeze-dried PLA nanoparticles by facilitating the redispersion of the lyophilized cake into optimal nanoparticles.

scholarly journals Effects of pH and Electrolytes on Castor Oil Emulsions with Various Stabilisers Using Khaya senegalensis Gum as an Emulsifier

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Deryl Nii Okantey Kuevi ◽  
Noble Kuntworbe ◽  
Enoch Ayertey
Keyword(s):  
Castor Oil ◽  
Xanthan Gum ◽  
Hydroxypropyl Methylcellulose ◽  
Physical Stability ◽  
Tween 80 ◽  
Volume Data ◽  
Emulsifying Property ◽  
Khaya Senegalensis ◽  
Effects Of Ph ◽  
The Stability

Dispersed systems such as emulsions are easily destabilised during processing and storage since they are thermodynamically unstable systems. It is for this reason emulsifiers/stabilisers are frequently employed in pharmaceutical emulsion formulations to increase their short- and long-term kinetic stability. This current study seeks to investigate the potential emulsifying property of gums obtained from Khaya senegalensis (family: Meliaceae) trees. Gums were collected, authenticated, oven-dried, milled, filtered, and purified using 96% ethanol. The microbial quality of the gum was assessed following the BP (2013) specifications. The purified gum was free from some selected pathogenic microorganisms, rendering the gum safe for consumption. The emulsifying property was investigated by formulating emulsions using castor oil and employing the dry gum method. The ratios of oil-to-water-to-gum for the formulation of a stable emulsion were determined. The stability of the emulsion was evaluated, and an effort was made to improve the stability by incorporating Tween 80, hydroxypropyl methylcellulose, and xanthan gum. From the results, it can be inferred that Tween 80 (0.5%) was able to stabilise the emulsion. Addition of xanthan gum worsened the creaming. The effects of pH (4.0, 5.5, 7.2, 9.0, and 11.0) and electrolytes (0.1 M of NaCl, KCl, and CaCl2) on the physical stability of oil-in-water emulsions were studied during 12 weeks of storage. Percentage creaming volume and whether there was phase inversion were the criteria used as the evaluation parameter. From the percentage creaming volume data, emulsions formulated with both gums showed the lowest creaming volumes at pH of 7.2, followed by the acidic regions (pH 4.0, 5.5), with the basic regions (pH 9.0, 11.0) recording the highest creaming volumes. The effects of the various electrolytes at a constant concentration of 0.1 M on the o/w emulsions were found in this order NaCl < KCl < CaCl2. This study proves that Khaya senegalensis gum can successfully be employed as an emulsifying agent in pharmaceutical formulations.

scholarly journals Effects Of Environmental Factors On The Dispersion Behavior Of Iron Oxide In Aqueous Solutions With Poly Acrylic Acid

2015 ◽  
Vol 60 (2) ◽  
pp. 1561-1564
Author(s):  
E.-H. Lee ◽  
K.-M. Kim ◽  
W.-Y. Maeng ◽  
D.-H. Hur
Keyword(s):  
Molecular Weight ◽  
Acrylic Acid ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Solution Ph ◽  
Molecular Weights ◽  
Aqueous Suspensions ◽  
Magnetite Particles ◽  
The Stability ◽  
Poly Acrylic Acid

Abstract After preparing aqueous suspensions from magnetite particles with a poly-acrylic acid, we investigated the effects of several experimental parameters. We characterized the stability of the suspensions using visual inspection, sedimentation, adsorption, and thermal stability of the dispersant. The dispersion stability is affected by the solution pH, the concentrations of magnetite particles, the molecular weight, the concentration of the dispersants, and the temperature. The stability of the suspensions increased as the concentration of the dispersant and the temperature increased. In terms of the molecular weights of the dispersant, the suspensions with dispersant of low-molecular weight (1800) were more stable than those of high-molecular weight (250000) at room temperature. However, at high temperature the suspensions with high-molecular weight showed stability. The adsorption efficiency of the dispersant was very low. The dispersant of high-molecular weight showed a higher thermal integrity than that of low-molecular weight. From this work, we obtained the optimum conditions for stable aqueous suspensions of magnetite particles.

ChemInform Abstract: The First Low Molecular Weight Antibiotic from Lactic Acid Bacteria: Reutericyclin (I), a New Tetramic Acid

ChemInform ◽  
2000 ◽  
Vol 31 (45) ◽  
pp. no-no
Author(s):  
Alexandra Hoeltzel ◽  
Michael G. Gaenzle ◽  
Graeme J. Nicholson ◽  
Walter P. Hammes ◽  
Guenther Jung
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Low Molecular Weight ◽  
Tetramic Acid

scholarly journals Blends of low molecular weight of poly lactic acid (PLA) with gondorukem (gum rosin)

2018 ◽  
Author(s):  
Mujtahid Kaavessina ◽  
Sperisa Distantina ◽  
Achmad Chafidz ◽  
Aditya Utama ◽  
Venisa Mega Puteri Anggraeni
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Poly Lactic Acid ◽  
Low Molecular Weight ◽  
Gum Rosin

Trans-tegumental absorption of L-alanine and L-leucine by a monogenean, Diclidophora merlangi

Parasitology ◽  
1978 ◽  
Vol 76 (1) ◽  
pp. 29-37 ◽  
Author(s):  
D. W. Halton
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Sea Water ◽  
Low Molecular Weight ◽  
Acid Uptake ◽  
Neutral Amino Acids ◽  
Freeze Dried ◽  
Significant Difference

SummaryAn in vitro investigation has been made of the relative roles of the gut and tegument in the absorption of the neutral amino acids L-alanine and L-leucine by a marine fish-gill parasite, Diclidophora merlangi. The use of ligatures to preclude oral ingestion of trace-labelled medium has proved inadequate, invariably damaging the tegument, as revealed by stereoscan electron microscopy, and resulting in artifactual levels of absorption. Three alternative procedures have given consistently reliable data on the route of entry of low molecular weight substrates. (1) Ultrastructural examination of worms previously incubated in electron-dense cationic tracers has shown that, in vitro, there is no oral intake of sea water. (2) The suspending of worms in trace-labelled medium with the mouth out of the medium and comparing amino acid uptake with that of worms totally immersed in medium has revealed no statistically significant difference in the absorption levels. (3) Application of section (freeze-dried) auto-radiography to detect diffusible isotope has demonstrated directly transtegumental absorption of a neutral amino acid. It is concluded from these experiments that Diclidophora has a tegumental transport system for absorbing certain neutral amino acids, and whilst, clearly, the worm is sanguinivorous and digests blood in a well-developed gut, it may also be capable of supplementing this diet with low molecular weight organic nutrient absorbed directly from sea water via the tegument.

scholarly journals Low Molecular Weight Heparin Protects Lung, Renal and Microcirculation Function in Patients with Covid-19 Pneumonia

2020 ◽  
Author(s):  
Li Ma ◽  
Yigang Zeng ◽  
Bing Zhao ◽  
LiLi Xu ◽  
Jian Li ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Renal Function ◽  
Lactic Acid ◽  
Acid Content ◽  
Low Molecular Weight Heparin ◽  
Arterial Oxygen ◽  
Control Group ◽  
Low Molecular Weight ◽  
Arterial Blood ◽  
Lactic Acid Content

Abstract BackgroundCoronavirus disease 2019 (Covid-19) remains a serious health threat worldwide. It is crucial to explore effective treatment measures that reduce mortality. Our aim was to investigate whether low molecular weight heparin (LMWH) can reduce organ injury in patients with Covid-19 pneumonia.MethodsA retrospective study was conducted at the Shanghai Public Health Clinical Center. We initiated a LMWH protocol from January 18th 2020. LMWH was injected subcutaneously at 4100U per day until the D-dimer(DD) level returned to normal, or 5-7 days after admission, whichever occurred first. Admitted patients who received LMWH between January 18th and February 17th 2020 were assigned to the LMWH group. Patients admitted between January 18th and February 17th who did not receive LMWH anticoagulant therapy were the control group. All patients in both groups were aged >18 years, were not pregnant, had no tumors and were in accordance with the following inclusion criteria: 1) DD increased on admission; 2) Body mass index(BMI) >30; 3) History of diabetes. The exclusion criteria were: 1) Platelets <30x109/L or fibrinogen <150 mg/dL; 2) Pregnancy and lactation; 3) Presence of blood system diseases; 4) Immunosuppression; 5) Diseases with a potential risk of bleeding; 6) Receiving anticoagulant drugs or antiplatelet drugs during treatment. General clinical information, indicators for renal function, arterial blood gas analyses and blood lactic acid content were recorded in the two groups 0 (Day 0), 3 (Day 3), 7 (Day 7), and 11 (Day 11) and 15 (Day 15) days after admission.ResultsThere were 48 patients in the LMWH group and 74 patients in the control group. General information, including age, gender, co-existing diseases and onset-to-admission time in both groups was similar. Compared to the control group, LMWH treatment improved the estimated glomerular filtration rate (eGFR) reduced the serum creatinine level (Scr), blood urea nitrogen (BUN)，arterial blood carbon dioxide partial pressure (PaCO2) and arterial blood lactic acid content. However, LMWH treatment reduced arterial oxygen partial pressure (PaO2) and arterial oxygen saturation (SaO2).ConclusionLMWH might be beneficial to improve renal function, CO2 discharge and microcirculation during the early phase of Covid-19 patients . Further randomized controlled trials(RCTs) are warranted in order to further investigate this issue.Trial registrationChiCTR, ChiCTR2000034796. Registered 19 July 2020 - Retrospectively registered, http:// www. chictr.org.cn/listbycreater.aspx.

Sign in / Sign up

Export Citation Format

Share Document