Dear Nasrin

Pls. find the attached files,

Hoping this will be helpful to your project, good luck

Regards

Prof. Houda Kawas

https://books.google.com/books?id=MWPLBQAAQBAJ&pg=PA415&lpg=PA415&dq=conjugate+biological+molecules+with+hydroxyl+groups&source=bl&ots=qoFHN5kPtb&sig=VNqgDOf7LkqoOIceGGOix6zxD-0&hl=ar&sa=X&ved=0ahUKEwjYvJvBovfUAhXjFJoKHb9sBtoQ6AEIWTAG#v=onepage&q=conjugate%20biological%20molecules%20with%20hydroxyl%20groups&f=false

https://opentextbc.ca/biology/chapter/2-3-biological-molecules/

https://chem.libretexts.org/Textbook_Maps/Organic_Chemistry_Textbook_Maps/Map%3A_Organic_Chemistry_with_a_Biological_Emphasis_(Soderberg)/Chapter_01%3A_Chapter_1%3A_Introduction_to_organic_structure_and_bonding_I/1.2%3A_Functional_groups_and_organic_nomenclature

http://pubs.acs.org/doi/abs/10.1021/bc00032a002?journalCode=bcches

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763257/

http://www.biologydiscussion.com/biomolecules/biomolecules-top-4-classes-of-biomolecules/11169

https://books.google.com/books?id=VbVsSG23HPQC&pg=PA90&lpg=PA90&dq=conjugate+biological+molecules+to+COO-&source=bl&ots=XGE6cfEIHj&sig=citK0CcCvMznaUwGTZOeIZI5BdQ&hl=ar&sa=X&ved=0ahUKEwi8-KPso_fUAhUCJpoKHdjDAtgQ6AEIKTAB#v=onepage&q=conjugate%20biological%20molecules%20to%20COO-&f=false

Thanks your kind answer. 

You most welcome

Hoping this will be helpful to your project, good luck

http://www.csun.edu/~jm77307/pH%20and%20Buffers.pdf

http://higheredbcs.wiley.com/legacy/college/pratt/0471393878/student/review/acid_base/7_buffers.html

https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-biology-learning-center/protein-biology-resource-library/pierce-protein-methods/chemistry-crosslinking.html

http://leah4sci.com/amino-acid-charge-in-zwitterions-and-isoelectric-point-mcat-tutorial/

http://www.xula.edu/chemistry/documents/biolab/Carroll%20lab%20Chap%204.pdf

http://www.sigmaaldrich.com/safc/news-and-resource-center/technical-reference-library/linking-biological-molecules-to-hpapis.html

https://books.google.com/books?id=88NpO6DqiyIC&pg=PA168&lpg=PA168&dq=conjugate+biological+molecules+to+NH3%2B+groups&source=bl&ots=HN3zvcVN10&sig=SmIMT4LzCXoQB3IUxABoYB8x_mE&hl=ar&sa=X&ved=0ahUKEwjxk9uEpPfUAhVFD5oKHWzgDGcQ6AEITzAG#v=onepage&q=conjugate%20biological%20molecules%20to%20NH3%2B%20groups&f=false

Article A review of ligand tethered surface engineered carbon nanotubes