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Wood V, Kellerman MA, Groves K, Quaglia M, Topp EM, Matejtschuk P, Dalby PA. Investigation of the Solid-State Interactions in Lyophilized Human G-CSF Using Hydrogen-Deuterium Exchange Mass Spectrometry. Mol Pharm 2024; 21:1965-1976. [PMID: 38516985 PMCID: PMC10988552 DOI: 10.1021/acs.molpharmaceut.3c01211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/13/2024] [Accepted: 03/13/2024] [Indexed: 03/23/2024]
Abstract
Hydrogen/deuterium exchange mass spectrometry (HDX-MS) previously elucidated the interactions between excipients and proteins for liquid granulocyte colony stimulating factor (G-CSF) formulations, confirming predictions made using computational structure docking. More recently, solid-state HDX mass spectrometry (ssHDX-MS) was developed for proteins in the lyophilized state. Deuterium uptake in ssHDX-MS has been shown for various proteins, including monoclonal antibodies, to be highly correlated with storage stability, as measured by protein aggregation and chemical degradation. As G-CSF is known to lose activity through aggregation upon lyophilization, we applied the ssHDX-MS method with peptide mapping to four different lyophilized formulations of G-CSF to compare the impact of three excipients on local structure and exchange dynamics. HDX at 22 °C was confirmed to correlate well with the monomer content remaining after lyophilization and storage at -20 °C, with sucrose providing the greatest protection, and then phenylalanine, mannitol, and no excipient leading to progressively less protection. Storage at 45 °C led to little difference in final monomer content among the formulations, and so there was no discernible relationship with total deuterium uptake on ssHDX. Incubation at 45 °C may have led to a structural conformation and/or aggregation mechanism no longer probed by HDX at 22 °C. Such a conformational change was observed previously at 37 °C for liquid-formulated G-CSF using NMR. Peptide mapping revealed that tolerance to lyophilization and -20 °C storage was linked to increased stability in the small helix, loop AB, helix C, and loop CD. LC-MS HDX and NMR had previously linked loop AB and loop CD to the formation of a native-like state (N*) prior to aggregation in liquid formulations, suggesting a similar structural basis for G-CSF aggregation in the liquid and solid states.
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Affiliation(s)
- Victoria
E. Wood
- Department
of Biochemical Engineering, University College
London, London WC1E 6BT, United
Kingdom
| | - Mark-Adam Kellerman
- Department
of Biochemical Engineering, University College
London, London WC1E 6BT, United
Kingdom
| | - Kate Groves
- LGC, Queens Road, Teddington, Middlesex TQ11 0LY, United Kingdom
| | - Milena Quaglia
- LGC, Queens Road, Teddington, Middlesex TQ11 0LY, United Kingdom
| | - Elizabeth M. Topp
- Department
of Industrial and Molecular Pharmaceutics, College of Pharmacy, and
Davidson School of Chemical Engineering, College of Engineering Purdue University, West Lafayette, Indiana 47907, United States
| | - Paul Matejtschuk
- Standardisation
Science, NIBSC, Medicines & Healthcare
Products Regulatory Agency, South Mimms, Hertfordshire EN6 3QG, United
Kingdom
| | - Paul A. Dalby
- Department
of Biochemical Engineering, University College
London, London WC1E 6BT, United
Kingdom
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2
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Zhang C, Berg A, Joe CCD, Dalby PA, Douglas AD. Lyophilization to enable distribution of ChAdOx1 and ChAdOx2 adenovirus-vectored vaccines without refrigeration. NPJ Vaccines 2023; 8:85. [PMID: 37277337 PMCID: PMC10240132 DOI: 10.1038/s41541-023-00674-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 05/12/2023] [Indexed: 06/07/2023] Open
Abstract
Distribution of vaccines which require refrigerated or frozen storage can be challenging and expensive. The adenovirus vector platform has been widely used for COVID-19 vaccines while several further candidate vaccines using the platform are in clinical development. In current liquid formulations, adenoviruses require distribution at 2-8 °C. The development of formulations suitable for ambient temperature distribution would be advantageous. Previous peer-reviewed reports of adenovirus lyophilization are relatively limited. Here, we report the development of a formulation and process for lyophilization of simian adenovirus-vectored vaccines based on the ChAdOx1 platform. We describe the iterative selection of excipients using a design of experiments approach, and iterative cycle improvement to achieve both preservation of potency and satisfactory cake appearance. The resulting method achieved in-process infectivity titre loss of around 50%. After drying, there was negligible further loss over a month at 30 °C. Around 30% of the predrying infectivity remained after a month at 45 °C. This performance is likely to be suitable for 'last leg' distribution at ambient temperature. This work may also facilitate the development of other product presentations using dried simian adenovirus-vectored vaccines.
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Affiliation(s)
- Cheng Zhang
- Department of Biochemical Engineering, University College London, Bernard Katz Building, Gower Street, London, WC1E 6BT, United Kingdom
| | - Adam Berg
- Jenner Institute, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, OX3 7DQ, Oxford, United Kingdom
| | - Carina C D Joe
- Jenner Institute, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, OX3 7DQ, Oxford, United Kingdom
| | - Paul A Dalby
- Department of Biochemical Engineering, University College London, Bernard Katz Building, Gower Street, London, WC1E 6BT, United Kingdom
| | - Alexander D Douglas
- Jenner Institute, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, OX3 7DQ, Oxford, United Kingdom.
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Investigating Alternative Container Formats for Lyophilization of Biological Materials Using Diphtheria Antitoxin Monoclonal Antibody as a Model Molecule. Pharmaceutics 2021; 13:pharmaceutics13111948. [PMID: 34834363 PMCID: PMC8620784 DOI: 10.3390/pharmaceutics13111948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/09/2021] [Accepted: 11/12/2021] [Indexed: 11/16/2022] Open
Abstract
When preparing biological reference materials, the stability of the lyophilized product is critical for long-term storage, particularly in order to meet WHO International Standards, which are not assigned expiry dates but are expected to be in use for several decades. Glass ampoules are typically used by the National Institute for Biological Standards and Control (NIBSC) for the lyophilization of biological materials. More recently, a clear need has arisen for the filling of smaller volumes, for which ampoules may not be optimal. We investigated the use of plastic microtubes as an alternative container for small volume fills. In this study, a recombinant diphtheria antitoxin monoclonal antibody (DATMAB) was used as a model molecule to investigate the suitability of plastic microtubes for filling small volumes. The stability and quality of the dried material was assessed after an accelerated degradation study using a toxin neutralization test and size exclusion HPLC. While microtubes have shown some promise in the past for use in the lyophilization of some biological materials, issues with stability may arise when more labile materials are freeze-dried. We demonstrate here that the microtube format is unsuitable for ensuring the stability of this monoclonal antibody.
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4
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Ward KR, Matejtschuk P. The Principles of Freeze-Drying and Application of Analytical Technologies. Methods Mol Biol 2021; 2180:99-127. [PMID: 32797409 DOI: 10.1007/978-1-0716-0783-1_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Freeze-drying is a complex process despite the relatively small number of steps involved, since the freezing, sublimation, desorption, and reconstitution processes all play a part in determining the success or otherwise of the final product qualities, and each stage can impose different stresses on a product. This is particularly the case with many fragile biological samples, which require great care in the selection of formulation additives such as protective agents and other stabilizers. Despite this, the process is widely used, not least because once any such processing stresses can be overcome, the result is typically a significantly more stable product than was the case with the starting material. Indeed, lyophilization may be considered a gentler method than conventional air-drying methods, which tend to apply heat to the product rather than starting by removing heat as is the case here. Additionally, due to the high surface area to volume ratio, freeze-dried materials tend to be drier than their conventionally dried counterparts and also rehydrate more rapidly. This chapter provides an overview of freeze-drying (lyophilization) of biological specimens with particular reference to the importance of formulation development, characterization, and cycle development factors necessary for the commercial exploitation of freeze-dried products, and reviews the recent developments in analytical methods which have come to underpin modern freeze-drying practice.
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Affiliation(s)
| | - Paul Matejtschuk
- National Institute for Biological Standards and Control (NIBSC), Potters Bar, UK
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5
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von Stosch M, Schenkendorf R, Geldhof G, Varsakelis C, Mariti M, Dessoy S, Vandercammen A, Pysik A, Sanders M. Working within the Design Space: Do Our Static Process Characterization Methods Suffice? Pharmaceutics 2020; 12:E562. [PMID: 32560435 PMCID: PMC7356980 DOI: 10.3390/pharmaceutics12060562] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 11/29/2022] Open
Abstract
The Process Analytical Technology initiative and Quality by Design paradigm have led to changes in the guidelines and views of how to develop drug manufacturing processes. On this occasion the concept of the design space, which describes the impact of process parameters and material attributes on the attributes of the product, was introduced in the ICH Q8 guideline. The way the design space is defined and can be presented for regulatory approval seems to be left to the applicants, among who at least a consensus on how to characterize the design space seems to have evolved. The large majority of design spaces described in publications seem to follow a "static" statistical experimentation and modeling approach. Given that temporal deviations in the process parameters (i.e., moving within the design space) are of a dynamic nature, static approaches might not suffice for the consideration of the implications of variations in the values of the process parameters. In this paper, different forms of design space representations are discussed and the current consensus is challenged, which in turn, establishes the need for a dynamic representation and characterization of the design space. Subsequently, selected approaches for a dynamic representation, characterization and validation which are proposed in the literature are discussed, also showcasing the opportunity to integrate the activities of process characterization, process monitoring and process control strategy development.
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Affiliation(s)
- Moritz von Stosch
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - René Schenkendorf
- Institute of Energy and Process Systems Engineering, TU Braunschweig, 38106 Braunschweig, Germany
- Center of Pharmaceutical Engineering, TU Braunschweig, 38106 Braunschweig, Germany
| | - Geoffroy Geldhof
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - Christos Varsakelis
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - Marco Mariti
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - Sandrine Dessoy
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - Annick Vandercammen
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - Alexander Pysik
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
| | - Matthew Sanders
- GSK, B-1330 Rixensart, Belgium; (M.v.S.); (G.G.); (C.V.); (M.M.); (S.D.); (A.V.); (A.P.); (M.S.)
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6
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Hussain MT, Forbes N, Perrie Y, Malik KP, Duru C, Matejtschuk P. Freeze-drying cycle optimization for the rapid preservation of protein-loaded liposomal formulations. Int J Pharm 2019; 573:118722. [PMID: 31705976 DOI: 10.1016/j.ijpharm.2019.118722] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/14/2019] [Accepted: 09/20/2019] [Indexed: 02/02/2023]
Abstract
Technology such as the use of microfluidics to generate liposomes has been well researched, yet the stabilisation of liposomal formulations is a major challenge to their greater implementation. To the best of our knowledge, this is the first study investigating the use of 96 well plates to freeze-dry ovalbumin (OVA) loaded neutral (DMPC:Chol and DSPC:Chol), anionic (DSPC:Chol:PS) and cationic (DSPC:Chol:DOTAP) liposomes. Through the use of high throughput screening, a freeze drying cycle was optimised; ramp freezing from from 4 °C to -45 °C, followed by primary drying at -30 °C and secondary drying at 30 °C under a vacuum of 0.1 mBar. These parameters maintained liposome physicochemical properties, with the liposomes remaining below 100 nm and were homogenous (polydispersity index of less than 0.2 post rehydration). Minimal leakage of the OVA protein was observed, with almost 100% OVA remaining encapsulated post rehydration of the formulations. Here we have identified a simple method that allows for the rapid screening and freeze-drying of a range of liposomal formulations.
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Affiliation(s)
- Maryam T Hussain
- Strathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, Glasgow G4 0RE, Scotland, United Kingdom
| | - Neil Forbes
- Strathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, Glasgow G4 0RE, Scotland, United Kingdom
| | - Yvonne Perrie
- Strathclyde Institute of Pharmacy and Biomedical Science, University of Strathclyde, Glasgow G4 0RE, Scotland, United Kingdom
| | - Kiran P Malik
- Standardisation Science, National Institute for Biological Standards & Control (NIBSC), Blanche Lane, South Mimms, Potters Bar EN6 3QG, United Kingdom
| | - Chinwe Duru
- Standardisation Science, National Institute for Biological Standards & Control (NIBSC), Blanche Lane, South Mimms, Potters Bar EN6 3QG, United Kingdom
| | - Paul Matejtschuk
- Standardisation Science, National Institute for Biological Standards & Control (NIBSC), Blanche Lane, South Mimms, Potters Bar EN6 3QG, United Kingdom.
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7
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Fernandez-Cerezo L, Wismer MK, Han I, Pollard JM. High throughput screening of ultrafiltration and diafiltration processing of monoclonal antibodies via the ambr® crossflow system. Biotechnol Prog 2019; 36:e2929. [PMID: 31622541 DOI: 10.1002/btpr.2929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/27/2019] [Accepted: 10/10/2019] [Indexed: 11/06/2022]
Abstract
As the biopharmaceutical industry moves toward high concentration of monoclonal antibody drug substance, additional development is required early on when material is still limited. A key constraint is the availability of predictive high-throughput low-volume filtration screening systems for bioprocess development. This particularly impacts final stages such as ultrafiltration/diafiltration steps where traditional scale-down systems need hundreds of milliliters of material per run. Recently, the ambr® crossflow system has been commercialized by Sartorius Stedim Biotech (SSB) to meet this need. It enables parallel high throughput experimentation by only using a fraction of typical material requirements. Critical parameters for predictive filtration systems include loading, mean transmembrane pressure (Δ P ¯ TMP ), and crossflow rate (QF ). While axial pressure drop (ΔPaxial ) across the cartridge is a function of these parameters, it plays a key role and similar values should result across scales. The ambr® crossflow system is first presented describing typical screening experiments. Its performance is then compared to a traditional pilot-scale tangential flow filtration (TFF) at defined conditions. The original ambr® crossflow (CF) cartridge underperformed resulting in ~20x lower ΔPaxial than the pilot-scale TFF flat-sheet cassette. With an objective to improve the scalability of the system, efforts were made to understand this scale difference. The ambr® CF cartridge was successfully modified by restricting the flow of the feed channel, and thus increasing its ΔPaxial . Additional studies across a range of loading (100-823 gm-2 ); Δ P ¯ TMP (12-18 psi); and QF (4-8 L/min/m2 ) were conducted in both scales. Comparable flux and aggregate levels were achieved.
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Affiliation(s)
- Lara Fernandez-Cerezo
- Downstream Process Development & Engineering, Merck & Co., Inc, Kenilworth, New Jersey
| | - Michael K Wismer
- Scientific Engineering & Design, Merck & Co., Inc, Kenilworth, New Jersey
| | - InKwan Han
- Downstream Process Development & Engineering, Merck & Co., Inc, Kenilworth, New Jersey
| | - Jennifer M Pollard
- Downstream Process Development & Engineering, Merck & Co., Inc, Kenilworth, New Jersey
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8
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Wang W, Ohtake S. Science and art of protein formulation development. Int J Pharm 2019; 568:118505. [PMID: 31306712 DOI: 10.1016/j.ijpharm.2019.118505] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 07/08/2019] [Accepted: 07/08/2019] [Indexed: 02/07/2023]
Abstract
Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.
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Affiliation(s)
- Wei Wang
- Biological Development, Bayer USA, LLC, 800 Dwight Way, Berkeley, CA 94710, United States.
| | - Satoshi Ohtake
- Pharmaceutical Research and Development, Pfizer Biotherapeutics Pharmaceutical Sciences, Chesterfield, MO 63017, United States
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9
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10
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11
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Effects of cooling rate in microscale and pilot scale freeze-drying – Variations in excipient polymorphs and protein secondary structure. Eur J Pharm Sci 2016; 95:72-81. [DOI: 10.1016/j.ejps.2016.05.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 05/04/2016] [Accepted: 05/20/2016] [Indexed: 11/23/2022]
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12
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Rašković B, Vatić S, Anđelković B, Blagojević V, Polović N. Optimizing storage conditions to prevent cold denaturation of trypsin for sequencing and to prolong its shelf life. Biochem Eng J 2016. [DOI: 10.1016/j.bej.2015.09.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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Rathore AS, Singh SK. Production of Protein Therapeutics in the Quality by Design (QbD) Paradigm. TOPICS IN MEDICINAL CHEMISTRY 2016. [DOI: 10.1007/7355_2015_5004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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14
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Peters BH, Leskinen JT, Molnár F, Ketolainen J. Impact of Microscale and Pilot-Scale Freeze-Drying on Protein Secondary Structures: Sucrose Formulations of Lysozyme and Catalase. J Pharm Sci 2015; 104:3710-3721. [DOI: 10.1002/jps.24615] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/28/2015] [Accepted: 08/04/2015] [Indexed: 11/08/2022]
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15
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Structural attributes of model protein formulations prepared by rapid freeze-drying cycles in a microscale heating stage. Eur J Pharm Biopharm 2014; 87:347-56. [DOI: 10.1016/j.ejpb.2014.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/24/2014] [Accepted: 02/27/2014] [Indexed: 11/23/2022]
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16
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Trnka H, Rantanen J, Grohganz H. Well-plate freeze-drying: a high throughput platform for screening of physical properties of freeze-dried formulations. Pharm Dev Technol 2014; 20:65-73. [DOI: 10.3109/10837450.2013.871028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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17
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A Small-Scale, Material-Saving Approach to Rank-Order Lyophilized Formulations Based on Reconstitution Time. J Pharm Innov 2013. [DOI: 10.1007/s12247-013-9158-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Borgognoni CF, Bevilacqua JDS, Pitombo RNDM. Freeze-drying microscopy in mathematical modeling of a biomaterial freeze-drying. BRAZ J PHARM SCI 2012. [DOI: 10.1590/s1984-82502012000200003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Transplantation brings hope for many patients. A multidisciplinary approach on this field aims at creating biologically functional tissues to be used as implants and prostheses. The freeze-drying process allows the fundamental properties of these materials to be preserved, making future manipulation and storage easier. Optimizing a freeze-drying cycle is of great importance since it aims at reducing process costs while increasing product quality of this time-and-energy-consuming process. Mathematical modeling comes as a tool to help a better understanding of the process variables behavior and consequently it helps optimization studies. Freeze-drying microscopy is a technique usually applied to determine critical temperatures of liquid formulations. It has been used in this work to determine the sublimation rates of a biological tissue freeze-drying. The sublimation rates were measured from the speed of the moving interface between the dried and the frozen layer under 21.33, 42.66 and 63.99 Pa. The studied variables were used in a theoretical model to simulate various temperature profiles of the freeze-drying process. Good agreement between the experimental and the simulated results was found.
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Ordidge GC, Mannall G, Liddell J, Dalby PA, Micheletti M. A generic hierarchical screening method for the analysis of microscale refolds using an automated robotic platform. Biotechnol Prog 2012; 28:435-44. [DOI: 10.1002/btpr.1502] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 11/21/2011] [Indexed: 11/07/2022]
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20
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Grant Y, Matejtschuk P, Bird C, Wadhwa M, Dalby PA. Freeze drying formulation using microscale and design of experiment approaches: a case study using granulocyte colony-stimulating factor. Biotechnol Lett 2011; 34:641-8. [DOI: 10.1007/s10529-011-0822-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 11/29/2011] [Indexed: 10/14/2022]
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21
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22
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Maks CJ, Wan XS, Ware JH, Romero-Weaver AL, Sanzari JK, Wilson JM, Rightnar S, Wroe AJ, Koss P, Gridley DS, Slater JM, Kennedy AR. Analysis of white blood cell counts in mice after gamma- or proton-radiation exposure. Radiat Res 2011; 176:170-6. [PMID: 21476859 DOI: 10.1667/rr2413.1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In the coming decades human space exploration is expected to move beyond low-Earth orbit. This transition involves increasing mission time and therefore an increased risk of radiation exposure from solar particle event (SPE) radiation. Acute radiation effects after exposure to SPE radiation are of prime importance due to potential mission-threatening consequences. The major objective of this study was to characterize the dose-response relationship for proton and γ radiation delivered at doses up to 2 Gy at high (0.5 Gy/min) and low (0.5 Gy/h) dose rates using white blood cell (WBC) counts as a biological end point. The results demonstrate a dose-dependent decrease in WBC counts in mice exposed to high- and low-dose-rate proton and γ radiation, suggesting that astronauts exposed to SPE-like radiation may experience a significant decrease in circulating leukocytes.
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Affiliation(s)
- Casey J Maks
- Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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Gaudet M, Remtulla N, Jackson SE, Main ERG, Bracewell DG, Aeppli G, Dalby PA. Protein denaturation and protein:drugs interactions from intrinsic protein fluorescence measurements at the nanolitre scale. Protein Sci 2010; 19:1544-54. [PMID: 20552687 DOI: 10.1002/pro.433] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein stability and ligand-binding affinity measurements are widely required for the formulation of biopharmaceutical proteins, protein engineering and drug screening within life science research. Current techniques either consume too much of often precious biological or compound materials, in large sample volumes, or alternatively require chemical labeling with fluorescent tags to achieve measurements at submicrolitre volumes with less sample. Here we present a quantitative and accurate method for the determination of protein stability and the affinity for small molecules, at only 1.5-20 nL optical sample volumes without the need for fluorescent labeling, and that takes advantage of the intrinsic tryptophan fluorescence of most proteins. Coupled to appropriate microfluidic sample preparation methods, the sample requirements could thus be reduced 85,000-fold to just 10(8) molecules. The stability of wild-type FKBP-12 and a destabilizing binding-pocket mutant are studied in the presence and absence of rapamycin, to demonstrate the potential of the technique to both drug screening and protein engineering. The results show that 75% of the interaction energy between FKBP-12 and rapamycin originates from residue Phe99 in the binding site.
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Affiliation(s)
- Matthieu Gaudet
- Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom
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24
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Ahmad SS, Dalby PA. Thermodynamic parameters for salt-induced reversible protein precipitation from automated microscale experiments. Biotechnol Bioeng 2010; 108:322-32. [DOI: 10.1002/bit.22957] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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