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Merivaara A, Kekkonen J, Monola J, Koivunotko E, Savolainen M, Silvast T, Svedström K, Diaz A, Holler M, Korhonen O, Yliperttula M, Valkonen S. Near-infrared analysis of nanofibrillated cellulose aerogel manufacturing. Int J Pharm 2022; 617:121581. [PMID: 35176331 DOI: 10.1016/j.ijpharm.2022.121581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 12/30/2022]
Abstract
Biomaterial aerogel fabrication by freeze-drying must be further improved to reduce the costs of lengthy freeze-drying cycles and to avoid the formation of spongy cryogels and collapse of the aerogel structures. Residual water content is a critical quality attribute of the freeze-dried product, which can be monitored in-line with near-infrared (NIR) spectroscopy. Predictive models of NIR have not been previously applied for biomaterials and the models were mostly focused on the prediction of only one formulation at a time. We recorded NIR spectra of different nanofibrillated cellulose (NFC) hydrogel formulations during the secondary drying and set up a partial least square regression model to predict their residual water contents. The model can be generalized to measure residual water of formulations with different NFC concentrations and the excipients, and the NFC fiber concentrations and excipients can be separated with the principal component analysis. Our results provide valuable information about the freeze-drying of biomaterials and aerogel fabrication, and how NIR spectroscopy can be utilized in the optimization of residual water content.
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Affiliation(s)
- Arto Merivaara
- Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland.
| | - Jere Kekkonen
- Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland; School of Pharmacy, University of Eastern Finland, 70210 Kuopio, Finland
| | - Julia Monola
- Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland; School of Pharmacy, University of Eastern Finland, 70210 Kuopio, Finland
| | - Elle Koivunotko
- Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland
| | - Marko Savolainen
- Optical measurements, VTT Technical Research Centre of Finland, Finland
| | - Tuomo Silvast
- SIB Labs, Faculty of Science and Forestry, University of Eastern Finland, Kuopio, Finland
| | - Kirsi Svedström
- Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
| | - Ana Diaz
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Mirko Holler
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Ossi Korhonen
- School of Pharmacy, University of Eastern Finland, 70210 Kuopio, Finland
| | - Marjo Yliperttula
- Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland.
| | - Sami Valkonen
- Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland; School of Pharmacy, University of Eastern Finland, 70210 Kuopio, Finland
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Zini J, Kekkonen J, Kaikkonen VA, Laaksonen T, Keränen P, Talala T, Mäkynen AJ, Yliperttula M, Nissinen I. Drug diffusivities in nanofibrillar cellulose hydrogel by combined time-resolved Raman and fluorescence spectroscopy. J Control Release 2021; 334:367-375. [PMID: 33930478 DOI: 10.1016/j.jconrel.2021.04.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 04/23/2021] [Accepted: 04/25/2021] [Indexed: 10/21/2022]
Abstract
Hydrogels, natural and synthetic origin, are actively studied for their use for implants and payload carriers. These biomaterials for delivery systems have enormous potential in basic biomedical research, drug development, and long-term delivery of biologics. Nanofibrillated cellulose (NFC) hydrogels, both natural and anionic (ANFC) ones, allow drug loading for immediate and controlled release via the slow drug dissolution of solid drug crystals into hydrogel and its subsequent release. This property makes NFC originated hydrogels an interesting non-toxic and non-human origin material as drug reservoir for long-term controlled release formulation or implant for patient care. A compelling tool for studying NFC hydrogels is Raman spectroscopy, which enables to resolve the chemical structures of different molecules in a high-water content like hydrogels, since Raman spectroscopy is insensitive to water molecules. That offers real time investigation of label-free drugs and their release in high-water-content media. Despite the huge potential of Raman spectroscopy in bio-pharmaceutical applications, the strong fluorescence background of many drug samples masking the faint Raman signal has restricted the widespread use of it. In this study we used a Raman spectrometer capable of suppressing the unpleasant fluorescence background by combining a pulsed laser and time-resolved complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode (SPAD) line sensor for the label-free investigation of Metronidazole and Vitamin C diffusivities in ANFC. The results show the possibility to modulate the ANFC-based implants and drug delivery systems, when the release rate needs to be set to a desired value. More importantly, the now developed label free real-time method is universal and can be adapted to any hydrogel/drug combination for producing reliable drug diffusion coefficient data in complex and heterogeneous systems, where traditional sampling-based methods are cumbersome to use. The wide temporal range of the time-resolved CMOS SPAD sensors makes it possible to capture also the fluorescence decay of samples, giving rise to a combined time-resolved Raman and fluorescence spectroscopy, which provides additional information on the chemical, functional and structural changes in samples.
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Affiliation(s)
- Jacopo Zini
- Division of Pharmaceutical Biosciences, Drug Research Program, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland.
| | - Jere Kekkonen
- Circuits and Systems Research Unit, University of Oulu, 90014 Oulu, Finland.
| | - Ville A Kaikkonen
- Optoelectronics and Measurement Techniques Research Unit, University of Oulu, 90014 Oulu, Finland.
| | - Timo Laaksonen
- Division of Pharmaceutical Biosciences, Drug Research Program, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland.
| | - Pekka Keränen
- Circuits and Systems Research Unit, University of Oulu, 90014 Oulu, Finland.
| | - Tuomo Talala
- Circuits and Systems Research Unit, University of Oulu, 90014 Oulu, Finland.
| | - Anssi J Mäkynen
- Optoelectronics and Measurement Techniques Research Unit, University of Oulu, 90014 Oulu, Finland.
| | - Marjo Yliperttula
- Division of Pharmaceutical Biosciences, Drug Research Program, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland.
| | - Ilkka Nissinen
- Circuits and Systems Research Unit, University of Oulu, 90014 Oulu, Finland.
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Kekkonen J, Finnilä MAJ, Heikkilä J, Anttonen V, Nissinen I. Chemical imaging of human teeth by a time-resolved Raman spectrometer based on a CMOS single-photon avalanche diode line sensor. Analyst 2019; 144:6089-6097. [PMID: 31531497 DOI: 10.1039/c9an01136f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Raman spectroscopy is a powerful analytical tool to be used in many biomedical applications and could be potentially translated into clinical work. The challenge of Raman spectroscopy in biomedical applications is the high inherent fluorescence of biological samples. One promising method to suppress the fluorescence background is to use pulsed lasers and time-gated detectors but the complexity of time-gated systems has hindered their widespread usage. We present here chemical imaging of human teeth by means of a new kind of compact and practical fluorescence-suppressed Raman spectrometer based on a time-resolved 16 × 256 CMOS single-photon avalanche diode (SPAD) line sensor with an integrated 256-channel 3-bit on-chip time-to-digital converter. The chemical images were constructed by utilizing a simple unsupervised machine learning algorithm (k-means clustering). The high quality of Raman spectra measured with the time-resolved CMOS SPAD-based Raman spectrometer was verified by comparing the spectra to those collected with a commercial conventional continuous wave (CW) Raman spectrometer. The spectra measured by using the time-resolved CMOS SPAD-based Raman spectrometer had 4.4-8.8 times higher signal to peak-to-peak noise ratio values than the spectra from the CW Raman spectrometer when the same radiant exposure (∼300 J mm-2) was used with both spectrometers. This paper shows in practice the potential of time-resolved CMOS SPAD-based Raman spectroscopy in the field of biomedicine and we expect that the presented technology could pave the way for the development of new kind of compact and practical fluorescence-suppressed Raman spectrometers to be used both in biomedical research and clinical settings.
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Affiliation(s)
- Jere Kekkonen
- Circuits and Systems Research Unit, University of Oulu, 90014 Oulu, Finland.
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Kekkonen J, Nissinen J, Kostamovaara J, Nissinen I. Distance-Resolving Raman Radar Based on a Time-Correlated CMOS Single-Photon Avalanche Diode Line Sensor. Sensors (Basel) 2018; 18:s18103200. [PMID: 30248956 PMCID: PMC6210722 DOI: 10.3390/s18103200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 09/17/2018] [Accepted: 09/21/2018] [Indexed: 12/04/2022]
Abstract
Remote Raman spectroscopy is widely used to detect minerals, explosives and air pollution, for example. One of its main problems, however, is background radiation that is caused by ambient light and sample fluorescence. We present here, to the best of our knowledge, the first time a distance-resolving Raman radar device that is based on an adjustable, time-correlated complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode line sensor which can measure the location of the target sample simultaneously with the normal stand-off spectrometer operation and suppress the background radiation dramatically by means of sub-nanosecond time gating. A distance resolution of 3.75 cm could be verified simultaneously during normal spectrometer operation and Raman spectra of titanium dioxide were distinguished by this system at distances of 250 cm and 100 cm with illumination intensities of the background of 250 lux and 7600 lux, respectively. In addition, the major Raman peaks of olive oil, which has a fluorescence-to-Raman signal ratio of 33 and a fluorescence lifetime of 2.5 ns, were distinguished at a distance of 30 cm with a 250 lux background illumination intensity. We believe that this kind of time-correlated CMOS single-photon avalanche diode sensor could pave the way for new compact distance-resolving Raman radars for application where distance information within a range of several metres is needed at the same time as a Raman spectrum.
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Affiliation(s)
- Jere Kekkonen
- Circuits and Systems Research Unit, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland.
| | - Jan Nissinen
- Circuits and Systems Research Unit, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland.
| | - Juha Kostamovaara
- Circuits and Systems Research Unit, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland.
| | - Ilkka Nissinen
- Circuits and Systems Research Unit, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland.
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Vansteelant WMG, Kekkonen J, Byholm P. Wind conditions and geography shape the first outbound migration of juvenile honey buzzards and their distribution across sub-Saharan Africa. Proc Biol Sci 2017; 284:20170387. [PMID: 28539514 PMCID: PMC5454264 DOI: 10.1098/rspb.2017.0387] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/02/2017] [Indexed: 11/20/2022] Open
Abstract
Contemporary tracking studies reveal that low migratory connectivity between breeding and non-breeding ranges is common in migrant landbirds. It is unclear, however, how internal factors and early-life experiences of individual migrants shape the development of their migration routes and concomitant population-level non-breeding distributions. Stochastic wind conditions and geography may determine whether and where migrants end up by the end of their journey. We tested this hypothesis by satellite-tagging 31 fledgling honey buzzards Pernis apivorus from southern Finland and used a global atmospheric reanalysis model to estimate the wind conditions they encountered on their first outbound migration. Migration routes diverged rapidly upon departure and the birds eventually spread out across 3340 km of longitude. Using linear regression models, we show that the birds' longitudinal speeds were strongly affected by zonal wind speed, and negatively affected by latitudinal wind, with significant but minor differences between individuals. Eventually, 49% of variability in the birds' total longitudinal displacements was accounted for by wind conditions on migration. Some birds circumvented the Baltic Sea via Scandinavia or engaged in unusual downwind movements over the Mediterranean, which also affected the longitude at which these individuals arrived in sub-Saharan Africa. To understand why adult migrants use the migration routes and non-breeding sites they use, we must take into account the way in which wind conditions moulded their very first journeys. Our results present some of the first evidence into the mechanisms through which low migratory connectivity emerges.
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Affiliation(s)
- W M G Vansteelant
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94248, 1090 GE Amsterdam, The Netherlands
- Vansteelant Eco Research, Dijkgraaf 35, 6721 NJ Bennekom, The Netherlands
| | - J Kekkonen
- Department of Biosciences, University of Helsinki, PO Box 65, 00014 Helsinki, Finland
| | - P Byholm
- Bioeconomy Research Team, Novia University of Applied Sciences, 10600 Ekenäs, Finland
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Brommer JE, Hanski IK, Kekkonen J, Väisänen RA. Size differentiation in Finnish house sparrows follows Bergmann's rule with evidence of local adaptation. J Evol Biol 2014; 27:737-47. [DOI: 10.1111/jeb.12342] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/09/2014] [Accepted: 01/18/2014] [Indexed: 11/30/2022]
Affiliation(s)
- J. E. Brommer
- Department of Biology; University of Turku; Turku Finland
- Aronia Research and Development Institute; Åbo Akademi and Novia University of Applied Sciences; Ekenäs Finland
| | - I. K. Hanski
- Finnish Museum of Natural History; Helsinki Finland
| | - J. Kekkonen
- Department of Biosciences; University of Helsinki; Helsinki Finland
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Kekkonen J, Seppä P, Hanski IK, Jensen H, Väisänen RA, Brommer JE. Low genetic differentiation in a sedentary bird: house sparrow population genetics in a contiguous landscape. Heredity (Edinb) 2010; 106:183-90. [PMID: 20372181 DOI: 10.1038/hdy.2010.32] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The house sparrow Passer domesticus has been declining in abundance in many localities, including Finland. We studied the genetic diversity and differentiation of the house sparrow populations across Finland in the 1980s, at the onset of the species' decline in abundance. We genotyped 472 adult males (the less dispersive sex) from 13 locations in Finland (covering a range of 400 × 800 km) and one in Sweden (Stockholm) for 13 polymorphic microsatellite markers. Our analysis of Finnish ringing records showed that natal dispersal distances are limited (90% <16 km), which confirmed earlier finding from other countries. The Finnish populations were panmictic, and genetically very homogeneous and the limited dispersal was sufficiently large to maintain their connectivity. However, all Finnish populations differed significantly from the Stockholm population, even though direct geographical distance to it was often smaller than among Finnish populations. Hence, the open sea between Finland and Sweden appears to form a dispersal barrier for this species, whereas dispersal is much less constrained across the Finnish mainland (which lacks geographical barriers). Our findings provide a benchmark for conservation biologists and emphasize the influence of landscape structure on gene flow.
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Affiliation(s)
- J Kekkonen
- Department of Biological & Environmental Sciences, University of Helsinki, Helsinki, Finland.
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