要猜測出一個(gè)糖果罐里杰雷豆（一種豆形糖果）的數(shù)量很不容易，那么試試看只憑借觀察猜出一個(gè)細(xì)胞的重量（上圖左側(cè)）,。
最近,，一個(gè)研究小組完成了這個(gè)“壯舉”，他們只是使用了一架標(biāo)準(zhǔn)實(shí)驗(yàn)室顯微鏡和一個(gè)數(shù)字?jǐn)z像機(jī),，就成功測量出了細(xì)胞的重量,。研究人員將該技術(shù)成果在線發(fā)表于《物理評論快報(bào)》（PRL）上。
通過分析目標(biāo)物體如何彎曲以及折射光的情況,，研究人員使用圖像處理算法就能推斷出目標(biāo)物體的構(gòu)成,。
了解一個(gè)物體的構(gòu)成能幫助科學(xué)家推斷出它的密度（上圖右側(cè)），并且由于顯微鏡也可以被用于測量一個(gè)物體的尺寸和體積，這些數(shù)據(jù)統(tǒng)合起來能讓研究人員測算出細(xì)胞的質(zhì)量,。
研究報(bào)告指出,，通過使用這一技術(shù)，參與研究的科學(xué)家發(fā)現(xiàn)人體血紅細(xì)胞的平均干質(zhì)量為27.2萬億分之一克,。
這一數(shù)據(jù)與過去的測量值一致,，過去得到這個(gè)數(shù)據(jù)要依賴特別定制的儀器。
研究人員指出,，這個(gè)新方法有望能幫助監(jiān)控活的細(xì)胞如何生長以及如何隨著時(shí)間改變,，例如對疾病或者環(huán)境變化作出響應(yīng)等。（生物谷Bioon.com）
doi:10.1103/PhysRevLett.109.118105
PMC:
PMID:
Measurement of Single Cell Refractive Index, Dry Mass, Volume, and Density Using a Transillumination Microscope
Kevin G. Phillips1,*, Steven L. Jacques1, and Owen J. T. McCarty1,2
Phase contrast microscopy has become ubiquitous in the field of biology, particularly in qualitative investigations of cellular morphology. However, the use of quantitative phase retrieval methods and their connection to cellular refractive index and dry mass density remain under utilized. This is due in part to the restriction of phase and cellular mass determination to custom built instruments, involved mathematical analysis, and prohibitive sample perturbations. We introduce tomographic bright field imaging, an accessible optical imaging technique enabling the three dimensional measurement of cellular refractive index and dry mass density using a standard transillumination optical microscope. The validity of the technique is demonstrated on polystyrene spheres. The technique is then applied to the measurement of the refractive index, dry mass, volume, and density of red blood cells. This optical technique enables a simple and robust means to perform quantitative investigations of engineered and biological specimens in three dimensions using standard optical microscopes.
